TY - CONF
A1 - Kislenko, Evgeniia
T1 - Molecularly Imprinted Polymers for Fluorescence Sensing of the Herbecide 2,4-D
N2 - Application of pesticides is ubiquitous to better manage agricultural production. However, most of these compounds are harmful or toxic for humans and highly persistent in the environment, even in the crops themselves. Therefore, the rapid and reliable monitoring of pesticide residues is a very important area of environmental analysis. If conducted directly in the field, the use of fluorescence sensing methods is particularly attractive, because they allow for sensitive and rapid analyses while being very versatile. Recently, molecularly imprinted polymers (MIPs) have emerged as promising candidates for the primary sensing phase. Their robustness, low price and tunability render them an attractive alternative to more conventional biosensors based on antibodies.
At present, a number of MIP formats are available besides the initial bulk polymer monoliths. Core/shell micro- and nanoparticles are especially suitable for sensor applications. A thin shell provides many advantages compared to a bulk polymer, such as fast diffusion of analyte, homogeneity of binding cavities and a higher number of binding sites closer to the surface. A strategy for sensory MIP synthesis is to introduce the fluorophore covalently into the polymer layer. The fluorescent probe monomer may thus consist of a fluorophore unit, a polymerizable unit and a recognition unit.
One of the issues in targeting acidic pesticides such as 2,4-D is the fact that usually their deprotonated form is used for imprinting in organic solvents, commonly as the tetraalkylammonium salt. This approach harbours drawbacks when it comes to analytical rebinding, because real samples seldom contain such counterions. In our group, we have thus developed a new fluorescent probe monomer containing the 2-aminopyridine moiety, which forms strong enough intermolecular hydrogen bonds with the carboxylic acid group of neat 2,4-D. During a titration of the probe monomer with the analyte, hydrogen bond formation is indicated by spectral shifts and fluorescence enhancement. Crystallography studies verified complex formation. The higher fluorometric response of the core-shell MIP compared to a non-imprinted control polymer proved successful imprinting.
Here, we will discuss the pros and cons of neutral molecule vs. salt imprinting, potentially expanding the possibilities of fluorescent sensory MIPs.
T2 - MIP2018
CY - Hebrew University, Jerusalem, Israel
DA - 24.06.2018
KW - Molecularly imprinted polymers
KW - 2,4-D
KW - Fluorescence
KW - Sensing
PY - 2018
AN - OPUS4-45598
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Mansurova, Maria
T1 - Fluorescence-based optical system for the detection of total petroleum hydrocarbons in water and soil with smartphone read-out compatibility - Spectrocube, a sensor for rapid oil test in water and soil
N2 - Contamination of natural bodies of water with oil and lubricants (or generally, hydrocarbon derivatives such as petrol, fuel and others) is a commonly found phenomenon around the world due to the extensive production, transfer and use of fossil fuels. The timely identification of these contaminants is of utmost importance, since they directly affect water quality and represent a risk for wildlife and human health even in trace amounts.
In this work, we develop a simple system for the on-field detection of total petroleum hydrocarbons (TPH) in water and soil, the "Spectrocube". The test is based on the measurement of the fluorescence signal emitted by the molecular rotor 4-DNS-OH dye. This dye is embedded in a hydrophobic polymeric matrix (PVDF), avoiding interactions of water with the dye and providing a robust support for use in test-strip fashion. The test-strip’s fluorescence intensity increases linearly at low concentrations of TPH, reaching a saturation value at higher concentrations.
For excitation and evaluation of the test-strip fluorescence, a simple miniature optical system was designed. The system works semi-quantitatively as solvent-free TPH detection kit, as well as quantitatively when using a simple cyclopentane extraction step. To simplify the fluorescence read-out, the device is coupled to a tablet computer via Bluetooth, running a self-programmed software ("app").
T2 - Oil Spill India 2018
CY - New Delhi, India
DA - 05.07.2018
KW - Oil analysis
KW - Water analysis
KW - Fluorescence
KW - Spectrocube
KW - Rapid test
KW - Field test
KW - Spectroscopy
KW - Sensor
PY - 2018
AN - OPUS4-45606
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Mansurova, Maria
T1 - Embedded Fluorescence-Based Optical System for the Detection of Total Petroleum Hydrocarbons in Water and Soil
N2 - Contamination of natural bodies of water with oil and lubricants (or generally, hydrocarbon derivatives such as petrol, fuel and others) is a commonly found phenomenon around the world due to the extensive production, transfer and use of fossil fuels. In this work, we develop a simple system for the on-field detection of total petroleum hydrocarbons (TPH) in water and soil. The test is based on fluorescence emission of a 4-dimethylamino-4′-nitrostilbene derivative (4-DNS-OH). This fluorescent molecular rotor is embedded in a hydrophobic polymeric matrix (PVDF), avoiding interactions with water and providing a robust support for use in test-strip fashion. For the fluorescence detection a portable sensor device was developed, featuring two excitation LEDs, a micro-spectrometer and Bluetooth control. A limit of detection of at least 6 ppm of TPH in water was demonstrated.
T2 - Europtrode 2018
CY - Naples, Italy
DA - 25.03.2018
KW - Water
KW - Fluorescence
KW - Spectrocube
KW - Rapid test
KW - Oil
PY - 2018
AN - OPUS4-45605
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Homann, Christian
A1 - Peeters, Régis
A1 - Mirmajidi, Hana
A1 - Berg, Jessica
A1 - Fay, Michael
A1 - Rodrigues, Lucas Carvalho Veloso
A1 - Radicchi, Eros
A1 - Jain, Akhil
A1 - Speghini, Adolfo
A1 - Hemmer, Eva
T1 - Rapid microwave-assisted synthesis of morphology-controlled luminescent lanthanide-doped Gd2O2S nanostructures
N2 - Gadolinium oxysulfide (Gd2O2S) is an attractive material of demonstrated suitability for a variety of imaging applications, leveraging its magnetic, scintillating, and luminescent properties, particularly when doped with optically active lanthanide ions (Ln3+). For many of these applications, control over size and morphology at the nanoscale is crucial. This study demonstrates the rapid microwave-assisted Synthesis of colloidal Ln2O2S (Ln = Gd and dopants Yb, Er, Tb) nanostructures in as little as 20 min. Structural characterization using X-ray diffraction analysis (XRD), Raman spectroscopy, as well as Transmission electron microscopy (TEM), including elemental mapping via energy dispersive X-ray spectroscopy (EDS), unveiled the key role of elemental sulphur (S8) in the reaction mixtures for materials growth. By systematically varying the Ln-to-S ratio from 1 : 0.5 to 1 : 15, controlled morphologies ranging from triangular nanoplatelets to berry- and flower-like shapes were achieved. Doping with Er3+/Yb3+ endowed the nano-triangles with upconverting and near-infrared emitting properties. Tb3+-doped Gd2O2S exhibited the characteristic green Tb3+ emission under UV excitation, while also showing X-ray excited optical luminescence (XEOL), rendering the material interesting as a potential nano-scintillator.
KW - Upconversion
KW - Microwave-assisted synthesis
KW - Synthesis
KW - Fluorescence
KW - Nano
KW - Particle
KW - NIR
KW - XRD
KW - X-ray fluoressence
KW - Morphology control
KW - Raman
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647907
DO - https://doi.org/10.1039/D5TC01646K
SN - 2050-7526
VL - 13
IS - 35
SP - 18492
EP - 18507
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-64790
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Rurack, Knut
T1 - The Integration of Fluorescent Probes with Sensing Matrices
N2 - Integrating fluorescent probes with sensing matrices presents a major challenge because usually, when confined in a rather rigid matrix, fluorophores tend to behave completely different than for instance in the molecular state in solution. The lecture reviews the major strategies that have been devised recently to circumvent such issues with special focus on the works carried out in this field by BAM’s Chemical and Optical Sensing Division. Moreover, it will be shown that by using certain strategies not only can the response behavior be retained but synergistic effects can even endow the hybrid with a much better performance than the probe molecule alone.
T2 - GDCh-Kolloquium
CY - Braunschweig, Germany
DA - 14.11.2016
KW - Fluorescence
KW - Probes
KW - Sensor
KW - Molecularly imprinted polymers
KW - Gated release systems
PY - 2016
AN - OPUS4-38794
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Rurack, Knut
T1 - Improving the Sensing Performance of Macrocycle-containing Fluorescent Probes by Integration into Mesoporous Silica
N2 - Macrocycle-containing fluorescent probes continue to be one of the most popular classes of indicator molecules for the sensitive optical detection of ionic inorganic analytes, in particular metal ions, since the first integration of crown ether building blocks into chromophoric π systems more than 30 years ago. However, whereas a large multitude of such probes have been described for operation in organic or mixed aqueous environments, the step to realistic analytical media such as water samples, aqueous food extracts or body fluids is still scarce. On one hand, this is due to considerably low complex stability constants for instance for alkali and alkaline-earth metal ions. On the other hand, many classes of organic dyes that show favourable spectroscopic properties and ion-induced responses in organic solvents are not soluble in neat aqueous media and/or exhibit only significantly quenched fluorescence, even if transition metal ions are binding strongly to the receptor unit. A way to circumvent such problems in a rather simple manner is the steric incorporation of fluorescent probes into mesoporous silica nanomaterials. The local polarity in such pores, whether nascent or modified appropriately with functional silanes, resembles much more a quasi-organic environment while at the same time allowing for free diffusion of water and its cargo.
Two examples of powerful hybrid signalling systems will be presented, utilizing charge transfer-type indicator molecules that show inferior sensing properties in their molecular state. One example discusses mercury(II) determination over an extended concentration range and the other discusses silver(I) and mercury(II) discrimination simply on the basis of photophysical effects retained in the hybrid materials.
T2 - The 1st Nanjing/Dijon Symposium on Functional Macrocyclic Molecules
CY - Nanjing, People's Republic of China
DA - 09.07.2016
KW - Fluorescence
KW - Probes
KW - Macrocycles
KW - Mesoporous Silica
KW - Sensor
PY - 2016
AN - OPUS4-38795
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Rurack, Knut
T1 - Bright Long-Wavelength Pyrrolic Dyes - Prospects for Applications in Fluorescence Sensing
N2 - Since more than 20 years, optical spectroscopic techniques, in particular fluorescence-based methods, are on the rise in many different areas of chemical and biochemical analysis, with no end being in sight.1,2 Advances in miniaturization and remote applications on one hand and ground-breaking developments in microscopy and laser-based high-throughput instrumentation on the other hand have fuelled these developments substantially.3,4 At the core of utmost of these applications however is not only the instrument, but a small entity that is able to absorb and emit photons and thus to report on the actual (bio)chemistry that is going on in a particular sample of interest.5,6 Besides intense research on various types of luminescent particles (e.g., quantum dots and carbon dots) and proteins, dye chemistry has thus seen its revival and the number of publications dealing with the design, synthesis and application of new fluorescent dyes as probes, stains, labels or indicators is still continuing to grow.
Among the various classes of dyes available as bright fluorophores for a wavelength range that is compatible with many (bio)analytical applications and the respective instrumentation, in particular pyrrolic dyes that do not belong to the classical porphyrins or phthalocyanines have received strong attention recently. Starting perhaps with the revival of the traditional boron-dipyrromethene laser dye ca. 15 years ago,7 these so-called BODIPYs have developed into a colourful spectrum of different derivatives.8 However, the interest in expanding the range of pyrrole-containing π-systems beyond BODIPYs has also constantly increased and has brought about several other pyrrole-based ring systems such as diketopyrrolopyrroles9 or dipyrrolonaphthyridinediones which possess a favourable brightness and other interesting properties. The present contribution will give a critical overview of the field, pinpointing advantages and prospects as well as discussing potential aspects of improvement with an emphasis on the chemical sensing and the longer wavelength range.
T2 - Ninth International Conference on Porphyrins and Phthalocyanines
CY - Nanjing, People's Republic of China
DA - 03.07.2016
KW - Fluorescence
KW - Dyes
KW - Sensor
KW - NIR
KW - Pyrroles
PY - 2016
AN - OPUS4-38796
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Rurack, Knut
T1 - Reaction-based BODIPY dyes as powerful tools in fluorescence sensing applications
N2 - The reversible analyte-induced switching between a colourless leuco form of a dye and its coloured all-π-conjugated form is one of the oldest concepts in probe- or indicator-based optical analysis,1 constituting so-called “one-color indicators”.2 In contrast to colour changes in the visible region, for which usually a bond-forming or a non-covalent interaction between a functional group on an indicator and an analyte is responsible, the extraordinarily large shifts of 150–250 nm seen for leuco-to-all-π-conjugated transformation are only possible when the reaction takes place directly at a site that is an intrinsic part of a dye’s π-system; the classic case are triphenylmethane dyes.3 Despite its obvious potential, this approach has not been a very popular area of scientific research for decades, perhaps because it is much more difficult to implement selectivity than by modifying terminal functional groups. However, in recent years, reaction-based fluorescence probes have attracted increasing attention by virtue of their superior sensitivity.4,5
Nowadays, rhodamines and fluoresceins are by far the most prominent groups of reaction-based indicators.5 They are usually switched between a colourless and non-fluorescent and a greenish-yellowish absorbing and yellowish-reddish emitting form. Typically, the coloured and fluorescent form is ionic, while the colourless form is neutral, reactions having mainly be designed to occur at the end groups of the xanthenoid π-system. BODIPY dyes, with their favourable spectroscopic and chemical properties as well as facile wavelength tunability features have only very recently been explored into this direction.6,7 Reaction at the core dipyrrin framework of these dyes led to strong colour and fluorescence modulations with potential applications in materials sciences6 and cell imaging.7 The present contribution will highlight the mechanisms at play and the sensing performance realized so far, and will compare core-reactive approaches to reaction-based signalling that involves π-extension of BODIPYs.8,9
T2 - 11th International Conference on Porphyrins and Phthalocyanines (ICPP-11)
CY - Online meeting
DA - 26.06.2021
KW - Indicators
KW - Fluorescence
KW - Sensing
KW - BODIPY Dyes
PY - 2021
AN - OPUS4-54001
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Jiang, Shan
A1 - Gawlitza, Kornelia
A1 - Rurack, Knut
T1 - Dual-Fluorescent Nanoparticle Probes Consisting of a Carbon Nanodot Core and a Molecularly Imprinted Polymer Shell
N2 - Dual-fluorescent molecularly imprinted nanoparticles with a red-emissive carbon nanodot-doped silica core and a chlorogenic acid-imprinted fluorescent polymer layer are prepared and their use in ratiometric fluorometric analysis is described. Nanoparticle probes consisting of a shielded and stably emitting core and a shell with embedded binding sites that indicates the presence of an analyte with a change in emission allow for internally referenced measurements potentially accounting for detrimental influences from instrument drifts, light source fluctuations or sensor materials-related inhomogeneities.
KW - Molecular imprinting
KW - Fluorescence
KW - Core-shell particles
KW - Chlorogenic acid
KW - Ratiometric measurement
PY - 2021
DO - https://doi.org/10.1007/978-1-0716-1629-1_17
VL - 2359
SP - 195
EP - 208
PB - Springer
CY - Humana, New York, NY
AN - OPUS4-53336
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Tobias, Charlie
T1 - Dip-stick coated with Polystyrene-Silica Core-Shell particles for the detection of microbiological fuel contamination
N2 - The microbial contamination of fuels by fungi or bacteria presents risks such as corrosion and fuel system fouling, which can produce critical problems in refineries and distribution systems and has a significant economic impact at every phase of the process. Many factors have been cited as responsible for microbial growth, like the presence of water in the storage tanks. Indeed, only 1 % water in a storage system is enough for the growth of microorganisms like bacteria or yeasts, as well as for the development of fungal biomass at the oil/water interface.1
In this work, a rapid test for the accurate determination of genomic DNA from aqueous fuel extracts is presented. The detection is based on the employment of polystyrene-mesoporous silica core-shell particles, on which modified fluorescent molecular beacons are covalently grafted. Those beacons incorporate in the hairpin loop a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA subunit. The designed single-stranded molecular beacon contained fluorescein as an internal indicator and a quencher in its proximity when not hybridized. Upon hybridization in presence of the target sequence, the indicator and the quencher are spatially separated, resulting in fluorescence enhancement. To perform the assay the designed particles were disposed on different glass fiber strips to try to achieve a portable and sensitive rapid test. Assays showed that presence of genomic DNA extracts from bacteria down to 50–70 μg L-1 induces a fluorescence response. The optical read-out was adapted for on-site monitoring by adapting a 3D-printed case on a conventional smartphone, taking advantages of the CMOS detector sensitivity.2 Such embedded assembly allowed to detect genomic DNA in aqueous extracts down to the mg L-1 range and presents an interesting step toward on-site monitoring of fuel contamination.
T2 - Europtrode 2021
CY - Warsaw, Poland
DA - 28.11.2021
KW - Bacgteria
KW - Fungi
KW - Rapid test
KW - Fluorescence
KW - Smartphone
KW - Biofouling
PY - 2021
AN - OPUS4-53867
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Scholtz, Lena
T1 - Luminescent, nanoparticle-loaded polymer microparticles - comparing synthesis routes
N2 - Our comparison showed that the route used for the synthesis of luminescent, NP-loaded PSMPs can play a significant role for the luminescence properties, as well as the number of accessible SFGs, and hence subsequent functionalization. This should be considered for future applications.
T2 - Bunsen-Tagung 2023
CY - Berlin, Germany
DA - 05.06.2023
KW - Fluorescence
KW - Polymerization
KW - Microbeads
KW - Quantum dots
KW - Comparison
PY - 2023
AN - OPUS4-57628
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Fidan, Z.
A1 - Wende, A.
A1 - Resch-Genger, Ute
T1 - Visible and red emissive molecular beacons for optical temperature measurements and quality control in diagnostic assays utilizing temperature-dependent amplification reactions
N2 - Quality control requirements imposed on assays used in clinical diagnostics and point-of-care-diagnostic testing (POCT), utilizing amplification reactions performed at elevated temperatures of 35 to 95 °C are very stringent. As the temperature of a reaction vessel has a large impact on the specificity and sensitivity of the amplification reaction, simple tools for local in situ temperature sensing and monitoring are required for reaction and assay control. We describe here a platform of stem-and-loop structured DNA hairpins (molecular beacons, MBs), absorbing and emitting in the visible and red spectral region, rationally designed for precise temperature measurements in microfluidic assays for POCT, and their ap-plication for temperature measurements in a common DNA-based molecular biological assay utilizing thermophilic helicase-dependent amplification (tHDA). Spectroscopic studies of these MBs, rationally designed from DNA se-quences of different thermal stabilities, chosen not to interact with the DNA probes applied in the nucleic acid amplification assay, and temperature-dependent fluorescence measurements of MB-assay mixtures revealed the suitability of these MBs for temperature measurements directly in such an assay with a temperature resolution of about 0.5 °C without interferences from assay components. Combining two spectrally distinguishable MBs provides a broader response range and an increase in temperature sensitivity up to 0.1 °C. This approach will find future application for temperature monitoring and quality control in commercialized diagnostics assays using dried reagents and microfluidic chips as well as assays read out with tube and microplate readers and PCR detection systems for temperature measurements in the range of 35 to 95 °C.
KW - Miniaturization
KW - Fluorescence
KW - Temperature
KW - Sensor
KW - Assay
KW - Microfluidics
KW - DNA
KW - Dye
KW - Molecular beacon
KW - Molecular diagnostics
PY - 2016
DO - https://doi.org/10.1007/s00216-016-0088-6
SN - 1618-2642
VL - 409
IS - 6
SP - 1519
EP - 1529
PB - Springer
CY - Heidelberg
AN - OPUS4-39589
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Srivastava, Priyanka
A1 - Tavernaro, Isabella
A1 - Genger, C.
A1 - Welker, P.
A1 - Huebner, Oskar
A1 - Resch-Genger, Ute
T1 - Multicolor Polystyrene Nanosensors for the Monitoring of Acidic, Neutral, and Basic pH Values and Cellular Uptake Studies
N2 - A first tricolor fluorescent pH nanosensor is presented, which was rationally designed from biocompatible carboxylated polystyrene nanoparticles and two analyte-responsive molecular fluorophores. Its fabrication involved particle staining with a blue-red-emissive dyad, consisting of a rhodamine moiety responsive to acidic pH values and a pH-inert quinoline fluorophore, followed by the covalent attachment of a fluorescein dye to the particle surface that signals neutral and basic pH values with a green fluorescence. These sensor particles change their fluorescence from blue to red and green, depending on the pH and excitation wavelength, and enable ratiometric pH measurements in the pH range of 3.0−9.0. The localization of the different sensor dyes in the particle core and at the particle surface was confirmed with fluorescence microscopy utilizing analogously prepared polystyrene microparticles. To show the application potential of these polystyrene-based multicolor sensor particles, fluorescence microscopy studies with a human A549 cell line were performed, which revealed the cellular uptake of the pH nanosensor and the differently colored emissions in different cell organelles, that is, compartments of the endosomal-lysosomal pathway. Our results demonstrate the underexplored potential of biocompatible polystyrene particles for multicolor and multianalyte sensing and bioimaging utilizing hydrophobic and/or hydrophilic stimuli-responsive luminophores.
KW - Microparticle
KW - Fluorescence
KW - Sensor
KW - pH
KW - Quantum yield
KW - Multiplexing
KW - Imaging
KW - Cell
KW - Quality assurance
KW - Nano
KW - Polymer
KW - Bioimaging
KW - Particle
KW - Application
PY - 2022
DO - https://doi.org/10.1021/acs.analchem.2c00944
VL - 94
IS - 27
SP - 9656
EP - 9664
PB - ACS
AN - OPUS4-55365
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Wang, Cui
A1 - Reichenauer, F.
A1 - Kitzmann, W.R.
A1 - Kerzig, Ch.
A1 - Heintze, K.
A1 - Resch-Genger, Ute
T1 - Efficient Triplet-Triplet Annihilation Upconversion Sensitized by a Chromium(III) Complex via an Underexplored Energy Transfer Mechanism
N2 - Sensitized triplet-triplet annihilation upconversion (sTTA-UC) mainly relies on precious metal complexes thanks to their high intersystem crossing (ISC) efficiencies, excited state energies, and lifetimes, while complexes of abundant first-row transition metals were only rarely utilized and with often moderate UC quantum yields. [Cr(bpmp)2]3+ (bpmp = 2,6-bis(2-pyridylmethyl)pyridine) containing earth-abundant chromium possesses an absorption band suitable for green light excitation, a doublet excited state energy matching the triplet energy of 9,10-diphenyl anthracene (DPA), a close to millisecond excited state lifetime, and high photostability. Combined ISC and doublet-triplet energy transfer from excited [Cr(bpmp)2]3+ to DPA gives 3DPA with close-to-unity quantum yield. TTA of 3DPA furnishes greento-blue UC with a quantum yield of 12.0 % (close to the theoretical maximum). Sterically less-hindered anthracenes undergo a [4+4] cycloaddition with [Cr(bpmp)2]3+ and green light.
KW - Fluorescence
KW - Optical probe
KW - Sensor
KW - ph
KW - Quantum yield
KW - Quality assurance
KW - Cr(III)
KW - Lifetime
KW - Ligand
KW - Theory
KW - TTA-UC
KW - Energy transfer
KW - Upconversion
KW - Mechanism
KW - Anthracene
KW - Photochemistry
KW - DFT
KW - Cycloaddition
KW - Transient absorbtion spectroscopy
PY - 2022
DO - https://doi.org/10.1002/anie.202202238
VL - 61
IS - 24
SP - 1
EP - 8
PB - Wiley online library
AN - OPUS4-54604
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Pauli, Jutta
A1 - Würth, Christian
A1 - Güttler, Arne
A1 - Resch-Genger, Ute
T1 - Reliable Determination of the Signal-Relevant Spectroscopic Key Characteristics of Luminescent Reporters and Optical Probes for Imaging in the vis/NIR/SWIR
N2 - Introduction. Comparing different emitter classes and rationally designing the next generation of molecular and nanoscale probes for bioimaging applications require accurate and quantitative methods for the measurement of the key parameter photoluminescence quantum yield f.1 f equals the number of emitted per number of absorbed photons. This is particularly relevant for increasingly used fluorescence imaging in the short wave-infrared region (SWIR) ≥ 900 nm providing deeper penetration depths, a better image resolution, and an improved signal-to-noise or tumor-to-background ratio.2, 3 However, spectroscopic measurements in the SWIR are more challenging and require specific calibrations and standards.
T2 - EMIM 2021
CY - Göttingen, Germany
DA - 24.08.2021
KW - Fluorescence
KW - Optical probe
KW - Dye
KW - Photophysics
KW - Quantum yield
KW - Mechanism
KW - NIR
KW - SWIR
KW - Imaging
KW - Reference material
KW - Reliability
KW - Nano
KW - Particle
KW - Method
KW - Quality assurance
PY - 2021
AN - OPUS4-53233
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Design and Quantitative Characterization of Functional Molecular Chromophores and Nanomaterials with UV/vis/NIR/IR Emission – An Overview of Research Activities in Division Biophotonics
N2 - In the focus of division Biophotonics are the design, preparation, analytical and spectroscopic characterization, and application of molecular and nanoscale
functional materials, particularly materials with a photoluminescence in the visible, near infrared (NIR) and short-wave infrared (SWIR). This includes optical reporters for bioimaging and sensing, security and authentication barcodes, and materials for solid state lighting, energy conversion, and photovoltaics. For the identification of optimum particle structures quantitative spectroscopic studies are performed under application-relevant conditions, focusing on the key performance parameter photoluminescence quantum yield. In addition, simple, cost-efficient, and standardizable strategies for quantifying functional groups on the surface of nano- and microparticles are developed, here with a focus on optical assays and electrochemical titration methods, cross-validated by more advanced methods such as quantitative NMR. In addition, reference materials and reference products are developed for optical methods, particularly luminescence techniques, and for analytical methods utilized for the characterization of nanomaterials.
T2 - Projekttreffen Nile-Chrome 2.0
CY - Mainz, Germany
DA - 11.12.2023
KW - Fluorescence
KW - Quantum yield
KW - Optical spectroscopy
KW - Reference material
KW - Reference data
KW - Quality assurance
KW - Dye
KW - Reference product
KW - NIR
KW - SWIR
KW - Nano
KW - Particle
KW - Silica
KW - Polymer
KW - Surface group analysis
KW - Sensor molecules
PY - 2023
AN - OPUS4-59123
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Spectroscopic characterization of semiconductor and lanthanide-based nanocrystals with vis and NIR emission
N2 - Common approaches to improve the optical properties of semiconductor quantum dots and lanthanide doped nanophosphors present core/shell structures as radiationless deactivation at the particle surface is usually the main energy loss mechanism. This has led to increasingly sophisticated particle architectures using multishell systems with shells of different chemical composition and thickness and initiated an increasing number of quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield to identify optimum particle structures. This is particularly challenging in the long wavelength region > 1000 nm and for nonlinear emitters like upconversion nanocrystals. Here, we present suitable absolute methods to quantify the photoluminescence of these different emitters in the vis/NIR/IR and as function of excitation power density and underline the impact of such measurements on a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different size and particle architecture in different environments.
T2 - NANO 2018
CY - Hong Kong, People's Republic of China
DA - 24.06.2018
KW - Upconversion
KW - Semiconductor
KW - Quantum dot
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Modeling
KW - Size
PY - 2018
AN - OPUS4-45797
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Kage, Daniel
T1 - Fluorescence lifetime multiplex flow cytometry system (FliMFlow-MultiLife)
N2 - Flow cytometry is a common tool in biological research and clinical analyses. In current developments, there are two different tendencies of interest. Firstly, we face the need for analysis methods that are capable of addressing more and more involved analysis tasks, i.e., an increasing number of fluorescent codes and markers is required. Secondly, low-cost diagnostic tests, e.g. in disease recognition, are needed in routine application.
Lifetime encoding could be an attractive alternative to commonly applied color (spectral) encoding. By combining spectral and lifetime multiplexing, the number of simultaneously detectable codes might be increased by adding lifetime codes to the parameter space. Otherwise, instrumentation costs could be lowered using only lifetime encoding and thus avoiding costly excitation light sources and detectors.
Here, we report on our recent progress in time-resolved flow cytometry using dye-stained lifetime-encoded polymer microparticles as a model system. We could show that the discrimination of two lifetime codes is feasible. Moreover, the simultaneous detection of a spectrally different ligand fluorescence signal excited at the same wavelength as the lifetime code fluorescence could be demonstrated.
T2 - Photonik in den Lebenswissenschaften
CY - Berlin, Germany
DA - 09.11.2016
KW - Flow cytometry
KW - Fluorescence
KW - Life sciences
KW - Lifetime encoding
KW - Polymer particles
PY - 2016
AN - OPUS4-38249
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Otto, S.
ED - Scholz, Norman
ED - Behnke, Thomas
ED - Heinze, K.
T1 - Thermo-Chromium: A Contactless Optical Molecular Thermometer
N2 - The unparalleled excited-state potential-energy landscape of the chromium(III)-based dye [1]3+ ([Cr(ddpd)2]3+; ddpd=N,N’-dimethyl-N,N’-dipyridin-2-ylpyridin-2,6-diamine) enables a strong dual emission in the near infrared region. The temperature dependence of this dual emission allows the use of [1]3+ as an unprecedented molecular ratiometric thermometer in the 210–373 K temperature range in organic and in aqueous media. Incorporation of [1]3+ in biocompatible nanocarriers, such as 100 nm-sized polystyrene nanoparticles and solutol micelles, provides nanodimensional thermometers operating under physiological conditions.
KW - Temperature
KW - Sensor
KW - Dual emission
KW - Fluorescence
KW - Cr complex
KW - Nano
KW - Particle
KW - Micelle
KW - Probe
KW - Environment
PY - 2017
DO - https://doi.org/10.1002/chem.201701726
SN - 0947-6539
VL - 23
IS - 50
SP - 12131
EP - 12135
PB - Wiley-VCH
AN - OPUS4-42539
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Quantification of Parameters Affecting the Upconversion Luminescence of Lanthanide-Based Upconversion Nanocrystals
N2 - Lanthanide-based upconversion nanoparticles (UCNPs) like hexagonal Beta-NaYF4 UCNPs doped with Yb3+ and Er3+, which efficiently convert 976 nm light to ultraviolet, visible, and near infrared photons, offer new strategies for luminescence-based sensing, barcoding, and imaging. The properties of their upconversion (UC) luminescence (UCL) are, however, strongly influenced by particle size, the concentration and spatial arrangement of the dopant ions, surface chemistry including presence and thickness of surface passivation and shielding shells, microenvironment/presence of quenchers with high energy vibrations, and excitation power density (P). We present here a comprehensive study of the influence of UCNP size and particle architecture for Yb3+ and Er3+ co-doped NaYF4 core-only and core-shell nanostructures in the size range of about 5 nm to 50 nm, which underlines the importance of particle synthesis, surface chemistry, and quantitative luminescence measurements for mechanistic insights and the determination of application-relevant matrix- and P-dependent optimum dopand concentrations.
T2 - Materials Challenges in Alternative and Renewable Energy (MCARE) 2018
CY - Vancouver, BC, Canada
DA - 20.08.2018
KW - Upconverting nanoparticles
KW - Size
KW - Energy transfer
KW - Fluorescence
KW - Absolute fluorescence quantum yield
KW - Fluorescence decay kinetics
KW - Power density dependence
PY - 2018
AN - OPUS4-46393
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Kage, Daniel
T1 - Dye-stained lifetime-encoded polymer microbeads for application in time-resolved flow cytometry
N2 - Flow cytometry is a standard analytical tool for biological research and in medical applications. There are different requirements triggering recent device and method development depending on the desired field of application. One trend is governed by the need for an increasing number of simultaneously detectable codes, i.e., fluorescent labels. The other one focuses on cost-effective methods and development of miniaturized, portable devices.
Fluorophore encoding is usually based on spectral encoding. However, this approach is hampered by, e.g., spectral crosstalk. Additionally, the sensitivity of fluorescence intensity measurements to fluctuations in excitation light intensity and dye concentration limits the achievable number of detection channels. Moreover, spectral multiplexing typically requires several costly excitation light sources. Lifetime multiplexing and the discrimination between different encoding fluorophores and carrier beads based on their fluorescence decay kinetics could present an innovative alternative. Encoded beads, i.e., beads with lifetime codes corresponding to the surface chemistry, have been employed to evaluate the feasibility of this approach with a custom designed flow cytometer equipped with a pulsed light source and a fast detector for time-resolved measurements in a flow.
In a first step, we used steady state and time-resolved photoluminescence measurements for the spectroscopic characterization of micrometer-sized dye-stained PMMA beads. Subsequently, the potential use of these microbeads for flow cytometry applications was analyzed with a prototype flow cytometer with lifetime detection.
With our proof-of-concept studies, we could demonstrate that lifetime discrimination and simultaneous readout of a ligand fluorescence signal for analyte quantification is feasible with a set of dye-stained polymer microbeads at single wavelength excitation. These studies are expected to pave the road for new applications of fluorescence lifetime multiplexing in time-domain flow cytometry and bead-based assays in general.
T2 - DBS/EBS 2017
CY - Potsdam, Germany
DA - 20.03.2017
KW - Flow cytometry
KW - Fluorescence
KW - Life sciences
KW - Lifetime encoding
KW - Polymer particles
PY - 2017
AN - OPUS4-39996
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Choi, Youngeun
ED - Choi, Youngeun
ED - Kotthoff, L.
ED - Olejko, L.
ED - Resch-Genger, Ute
ED - Bald, Ilko
T1 - DNA origami-based Förster resonance energy-transfer nanoarrays and their application as ratiometric sensors
N2 - DNA origami nanostructures provide a platform where dye molecules can be arranged with nanoscale accuracy allowing to assemble multiple fluorophores without dye−dye aggregation. Aiming to develop a bright and sensitive ratiometric sensor system, we systematically studied the optical properties of nanoarrays of dyes built on DNA Origami platforms using a DNA template that provides a high versatility of label choice at minimum cost. The dyes are arranged at distances, at which they efficiently interact by Förster resonance energy transfer (FRET). To optimize array brightness, the FRET efficiencies between the donor fluorescein (FAM) and the acceptor cyanine 3 were determined for different sizes of the array and for different arrangements of the dye molecules within the array. By utilizing nanoarrays providing optimum FRET efficiency and brightness, we subsequently designed a ratiometric pH nanosensor using coumarin 343 as a pH-inert FRET donor and FAM as a pHresponsive acceptor. Our results indicate that the sensitivity of a ratiometric sensor can be improved simply by arranging the dyes into a well-defined array. The dyes used here can be easily replaced by other analyte-responsive dyes, demonstrating the huge potential of DNA nanotechnology for light harvesting, signal enhancement, and sensing schemes in life sciences.
KW - DNA
KW - Nanoparticle
KW - DNA Origami
KW - Array
KW - FRET
KW - Dye
KW - pH
KW - Nanosensor
KW - Fluorescence
PY - 2018
DO - https://doi.org/10.1021/acsami.8b03585
SN - 1944-8244
SN - 1944-8252
VL - 10
IS - 27
SP - 23295
EP - 23302
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-45798
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Tavernaro, Isabella
T1 - Design of Fluorescent, Amorphous Silica-NPs and their Versatile Use in Sensing Applications
N2 - Surface functionalized silica nanoparticles (SiO2-NP) gained great interest in the life and material sciences, as they can be used e.g. as drug carriers, fluorescent sensors, and multimodal labels in bioanalytical assays and imaging applications. They are highly stable, are easily produced and modified on a large scale at low cost and can be labeled or stained with a multitude of sensor dyes. These dye modified particle conjugates have several advantages as compared to conventional molecular probes like enhanced brightness, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, stained nanoparticles can enable the use of hydrophobic dyes in aqueous environments.
Here we present our work on multicolored sensors for the measurement of pH, oxygen and saccharides utilizing amorphous SiO2 NPs.
T2 - Focus Area Day Analytical Sciences 2023
CY - Berlin, Germany
DA - 20.04.2023
KW - Amorphous silica particles
KW - Particle Synthesis
KW - Nano
KW - Ratiometric Sensors
KW - Fluorescence
KW - pH probe
KW - Dye
PY - 2023
AN - OPUS4-59151
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Wang, Cui
ED - Otto, S.
ED - Dorn, M.
ED - Kreidt, E.
ED - Lebon, J.
ED - Srsan, L.
ED - di Martino-Fumo, P.
ED - Gerhards, M.
ED - Seitz, M.
ED - Heinze, K.
T1 - Deuterated Molecular Ruby with Record Luminescence Quantum Yield
N2 - The recently reported luminescent chromium(III) complex 13+ ([Cr(ddpd)2]3+; ddpd=N,N’-dimethyl-N,N’-dipyridine-2-yl-pyridine-2,6-diamine) shows exceptionally strong near-IR emission at 775 nm in water under ambient conditions (F=11%) with a microsecond lifetime as the ligand design in 13+ effectively eliminates non-radiative decay pathways, such as photosubstitution, back-intersystem crossing, and trigonal twists. In the absence of energy acceptors, such as dioxygen, the remaining decay pathways are energy transfer to high energy solvent and ligand oscillators, namely OH and CH stretching vibrations. Selective deuteration of the solvents and the ddpd ligands probes the efficiency of these oscillators in the excited state deactivation. Addressing these energytransfer pathways in the first and second coordination sphere furnishes a record 30% quantum yield and a 2.3 millisecond lifetime for a metal complex with an earth-abundant metal ion in solution at room temperature.
KW - Fluorescence
KW - Quantum yield
KW - Ligand design
KW - Cr(III)
KW - Complex
KW - Oxygen sensor
KW - NIR
KW - Fluorescence lifetime
PY - 2018
DO - https://doi.org/10.1002/ange.201711350
SN - 1521-3773
VL - 57
IS - 4
SP - 1112
EP - 1116
PB - Wiley-VCH Verlag & Co. KGaA
CY - Weinheim
AN - OPUS4-44045
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Measuring the Upconversion Luminescence of Ensemble and Single Particle Lanthanide-Based Upconversion Nanocrystals
N2 - Lanthanide-based upconversion nanoparticles (UCNPs) like hexagonal 𝛽-NaYF4 UCNPs doped with Yb3+ and Er3+, which efficiently convert 976 nm light to ultraviolet, visible, and near infrared photons, offer new strategies for luminescence-based sensing, barcoding, and Imaging. Their upconversion (UC) luminescence (UCL) features like UCL intensity, quantum yield, relative spectral distribution / UCL luminescence color, and luminescence decay kinetics are, however, strongly influenced by particle size, dopant ion concentration, particle architecture, surface chemistry including presence and thickness of surface passivation and shielding shells, microenvironment/presence of quenchers with high energy vibrations, and excitation power density (P).
We present here a comprehensive study of the influence of excitation power density on the UCL features of different types of UCNPs, focusing on Yb3+ and Er3+ co-doped NaYF4 core-only and core-shell nanostructures with different sizes and doping ion concentration, which underlines the importance of P-dependent optimum dopant concentrations for UCNP performance and the potential of P-tuning of UCL.
T2 - Materials Challenges in Alternative & Renewable Energy 2021 (MCARE 2021)
CY - Online meeting
DA - 19.07.2021
KW - Fluorescence
KW - Lifetime
KW - Method
KW - Stability
KW - Coating
KW - Surface chemistry
KW - Lanthanide
KW - Upconversion
KW - Nano
KW - Particle
KW - Single particle spectroscopy
KW - Quantum yield
KW - Microscopy
KW - Photophysics
PY - 2021
AN - OPUS4-53111
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Gorris, H.H.
A1 - Resch-Genger, Ute
T1 - Perspectives and challenges of photon-upconversion nanoparticles - Part II: Bioanalytical applications
N2 - In Part II of this Review series on lanthanide-doped photon-upconversion nanoparticles (UCNPs), we present and critically discuss the Performance and suitability of UCNPs as background-free luminescent Reporters in bioimaging and bioanalytical applications. The preparation of a biocompatible nanoparticle surface is an integral step for all life - science-related applications. UCNPs have found their way into a large number of diagnostic platforms, homogeneous and heterogeneous assay formats, and sensor applications. Many bioanalytical detection schemes involve Förster resonance energy transfert (FRET), which is still debated for UCNPs and Needs to be much improved. The Need for dedicated and standardized instruments as well as recent studies on the Dissolution and potential toxicity of UCNPs are addressed. Finally we outline future Trends and challenges in the field of upconversion.
KW - Fluorescence
KW - Lanthanide
KW - Upconversion
KW - Brightness
KW - Quantification
KW - Nanoparticle
KW - Absolute fluorometry
KW - NIR
KW - IR
KW - Quantum yield
KW - Assay
KW - Bioconjugation
KW - Imaging
KW - FRET
KW - Sensor
PY - 2017
DO - https://doi.org/10.1007/s00216-017-0482-8
SN - 1618-2650
SN - 1618-2642
VL - 409
IS - 25
SP - 5875
EP - 5890
PB - Springer
AN - OPUS4-41706
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Sloniec-Myszk, Jagoda
ED - Hennig, Andreas
T1 - Chiral, J-aggregate-forming dyes for alternative signal modulation mechanisms in self-immolative enzyme-activatable optical probes
N2 - Enzyme-activatable optical probes are important for future advances in cancer imaging, but may easily suffer from low signal-to-background ratios unless not optimized. To address this shortcoming, numerous mechanisms to modulate the fluorescence signal have been explored.
We report herein newly synthesized probes based on selfimmolative linkers containing chiral J-aggregate-forming dyes.
Signal modulation by formation of chiral J-aggregates is yet unexplored in optical enzyme probe design. The comprehensive characterization of the probes by absorption, CD, fluorescence, and time-resolved fluorescence spectroscopy revealed dye−dye interactions not observed for the free dyes in solution as well as dye−protein interactions with the enzyme. This suggested
that J-aggregate formation is challenging to achieve with current probe design and that interactions of the dyes with the Enzyme may interfere with achieving high signal-to-background ratios. The detailed understanding of the interactions provided herein provides valuable guidelines for the future design of similar probes.
KW - Signal amplification
KW - Fluorescence
KW - Quantum yield
KW - Optical spectroscopy
KW - Dye
KW - Cyanine
KW - Characterization
KW - Assay
KW - Chiral
KW - Aggregation
KW - Activatable probe
PY - 2016
DO - https://doi.org/10.1021/acs.jpcb.5b10526
SN - 1520-5207
SN - 1520-6106
VL - 120
IS - 5
SP - 877
EP - 885
PB - ACS Publications
AN - OPUS4-35949
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Effect of Particle Size and Excitation Power Density on the Luminescence Efficiency of Upconversion Nanocrystals in Different Dispersion Media
N2 - Upconversion nanoparticles (UCNPs) offer new strategies for luminescence-based sensing and imaging. One of the best studied materials are ..-NaYF4 UCNPs doped with 20 % Yb3+ and 2 % Er3+, which efficiently convert 976 nm light to photons emitted at 540 nm, 655 nm, and 845 nm, respectively, reveal long luminescence lifetimes (> 100 µs), are photostable and chemically inert. Their upconversion (UC) luminescence (UCL) properties are, however, strongly influenced by particle size, surface chemistry, and microenvironment. In addition, the multiphotonic absorption processes responsible for UCL render UCL excitation power density (..) dependent. This makes quantitative UCL measurements as well as the determination of UC quantum yields (.UC) very challenging.
The rational design of brighter UCNPs particle architectures and the interest in identifying optimum particle architectures for FRET-based sensing and imaging schemes, which often rely on core-only UCNPs to minimize donor-acceptor distances, encouraged us to assess the influence of particle size and P on UCL. Here, we present the photophysical properties of a series of hexagonal NaYF4 UCNPs with sizes from 10 to 43 nm with different surface ligands dispersed in organic solvents and water studied by steady state and time-resolved fluorometry as well as quantitatively by integrating sphere spectrometry with P varied over about three orders of magnitude. Our results underline the need for really quantitative luminescence studies for mechanistic insights and the potential of high P to compensate for UCL quenching due to high energy phonons and surface effects.
T2 - 15th Conference on Methods and Applications in Fluorescence
CY - Bruges, Belgium
DA - 10.09.2017
KW - Upconversion
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Photophysics
KW - Quantum yield
PY - 2017
AN - OPUS4-43181
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Güttler, Arne
A1 - Richter, Maria
A1 - Würth, Christian
A1 - Resch-Genger, Ute
T1 - New Reference Materials for Quantification and Standardization of Fluorescence-based Measurements
N2 - Luminescence techniques are amongst the most commonly used analytical methods in the life and material sciences due to their high sensitivity and non-destructive and multiparametric character. Photoluminescence signals are, however, affected by wavelength-, polarization-, and time-dependent instrument specific effects and the compound-specific photoluminescence quantum yield. The former hamper the comparability of fluorescence measurements, while the relative determination of the latter requires suitable quantum yield standards with well-known photoluminescence quantum yields. For the simple correction of instrument specific effects in the wavelength region of 300 nm to 950 nm, the set of the five certified spectral fluorescence standards (CRM) BAM-F001 – BAM-F005, has been extended to the NIR range by including two new fluorescence standards currently under certification.
T2 - 17th conference on Methods and Applications in Fluorescence
CY - Gothenburg, Sweden
DA - 11.09.2022
KW - Luminescence
KW - Photoluminescence
KW - Fluorescence
KW - Quantum yield
KW - Certified reference material
KW - Standard
PY - 2022
AN - OPUS4-56441
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Scholz, Norman
ED - Behnke, Thomas
T1 - Determination of the critical micelle concentration of neutral and ionic surfactants with fluorometry, conductometry, and surface tension - a method comparison
N2 - Micelles are of increasing importance as versatile carriers for hydrophobic substances and nanoprobes for a wide range of pharmaceutical, diagnostic, medical, and therapeutic applications. A key Parameter indicating the Formation and stability of micelles is the critical micelle concentration (CMC). In this respect, we determined the CMC of common anionic, cationic, and non-ionic surfactants fluorometrically using different fluorescent probes and fluorescence Parameters for Signal detection and ompared the results with conductometric and surface Tension measurements. Based upon These results, requirements, Advantages, and pitfalls of each methods are discussed. Our study underlines the versatility of fluorometric methods that do not impose specific requirements on surfactants and are especially suited for the quantification of very low CMC values. Conductivity and surface Tension measurements yield smaller uncertainties particularly for high CMC values, yet are more time- and substance consuming and not suitable for every surfactant.
KW - Fluorescence
KW - Methods
KW - Critical micelle concentration (CMC)
KW - Conductometry
KW - Fluorescence probe
KW - Dye
KW - Nile Red
KW - Pitfalls
KW - Method evaluation
KW - Uncertainty
PY - 2017
DO - https://doi.org/10.1007/s10895-018-2209-4
SN - 1053-0509
SN - 1573-4994
VL - 28
IS - 1
SP - 465
EP - 476
AN - OPUS4-43905
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Gorris, H.H.
T1 - Perspectives and challenges of photon-upconversion nanoparticles - Part I: routes to brighter particles and quantitative spectroscopic studies
N2 - Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been the Focus of many Research activities in materials and life sciences in the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. To fully exploit the application potential of These facinating nanomaterials, a number of challenges have to be overcome, such as the low brightness, particularly of small UCNPs, and the reliable quantification of the excitation-power-density-dependent upconversion luminescence. In this series of critical Reviews, recent developments in the design, Synthesis, optical-spectroscopic characterization, and application of UCNPs are presented with Special Focus on bioanalysis and the life sciences. Here we guide the reader from the Synthesis of UCNPs to different concepts to enhance their luminescence, including the required optical-spectroscopic assessment to quantify material Performance; surface modification strategies and bioanalytical applications as well as selected examples of the use of UCNPs as reporters in different Assay formats are addressed in part II. Future Trends and challenges in the field of upconversion are discussed with Special emphasis on UCNP Synthesis and material characterization, particularly quantitative luminescence studies.
KW - Fluorescence
KW - Lanthanide
KW - Upconversion
KW - Brightness
KW - Quantification
KW - Nanoparticle
KW - Absolute fluorometry
KW - NIR
KW - IR
KW - Quantum yield
PY - 2017
DO - https://doi.org/10.1007/s00216-017-0499-z
SN - 1618-2650
SN - 1618-2642
VL - 409
IS - 25
SP - 5855
EP - 5874
PB - Springer
AN - OPUS4-41665
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Witte, F.
A1 - Rietsch, P.
A1 - Sinha, S.
A1 - Krappe, A.
A1 - Joswig, J.-O.
A1 - Götze, J. P.
A1 - Nirmalananthan-Budau, Nithiya
A1 - Resch-Genger, Ute
A1 - Eigler, S.
A1 - Paulus, B.
T1 - Fluorescence Quenching in J‑Aggregates through the Formation of Unusual Metastable Dimers
N2 - Molecular aggregation alters the optical properties of a system as fluorescence may be activated or quenched. This is usually described within the well-established framework of H- and J-aggregates. While H-aggregates show nonfluorescent blueshifted absorption bands with respect to the isolated monomer, Jaggregates are fluorescent displaying a redshifted peak. In this publication, we employ a combined approach of experiment and theory to study the complex aggregation features and photophysical properties of diaminodicyanoquinone derivatives, which show unusual and puzzling nonfluorescent redshifted Absorption bands upon aggregation. Our theoretical analysis demonstrates that stable aggregates do not account for the experimental observations.
Instead, we propose an unprecedented mechanism involving metastable dimeric species formed from stable dimers to generate nonfluorescent J-aggregates. These results represent a novel kind of aggregation-induced optical effect and may have Broad implications for the photophysics of dye aggregates.
KW - Fluorescence
KW - Llifetime
KW - Dye
KW - Quantum yield
KW - Label
KW - Reporter
KW - Aggregation
KW - Monomer
KW - Heory
KW - Mechanism
KW - photophysics
PY - 2021
DO - https://doi.org/10.1021/acs.jpcb.1c01600
SN - 1520-5207
VL - 125
IS - 17
SP - 4438
EP - 4446
PB - ACS Publikations
AN - OPUS4-52619
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Introduction to Fluorescence Spectroscopy
N2 - A brief introduction to fluorescence spectroscopy will be provided, ranging from typically measured fluorescence quantities over instrument-specific contributions to measured fluorescence signals to selected applications. In this context, an overview of the photoluminescence properties of molecular and nanoscale luminescence reporters will be given including a brief insight into their photophysics and fluorescence standards designed by division Biophotonics for the calibration and instrument performance validation of fluorescence measuring devices will be presented.
T2 - Analytical Academy BAM
CY - Online meeting
DA - 17.11.2020
KW - Fluorescence
KW - Quality assurance
KW - Quantification
KW - Linearity
KW - Measurement uncertainty
KW - Method
KW - Nano particle
KW - Dye
PY - 2020
AN - OPUS4-51619
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Design and Quantitative Characterization of Functional Molecular Chromophores and Nanomaterials with UV/vis/NIR/IR Emission and Traceable Optical Measurements
N2 - Research of division Biophotonics at the Federal Institute for Materials Research and Testing (BAM) covers several topics including photophysics of molecular and nanocrystalline emitters, the development of signal enhancement, multiplexing, and barcoding strategies, surface group quantification, the rational design of different types of stimuli-responsive optical probes, and concepts and reference materials for the validation of optical-spectroscopic measurements. In the following representative examples for each of these topics are given. Also, current developments like single particle spectroscopy and flow cytometry with lifetime detection and newly certified fluorescence quantum yield standards are presented.
T2 - Kolloquium BfR
CY - Berlin, Germany
DA - 12.10.2020
KW - Fluorescence
KW - Quantitative spectroscopy
KW - Single particle spectroscopy
KW - Multiplexing
KW - Reference materials
KW - Optical probes
KW - Sensor molecules
KW - Assay
KW - Dye
KW - Quantum yield
KW - Method development
KW - surface group analysis
KW - synthesis
KW - fluorescence standards
PY - 2020
AN - OPUS4-51449
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Scholtz, Lena
T1 - Luminescence encoding of polymer microbeads with nanocrystals during polymerization
N2 - The Goal & Motivation
- Spherical polymer beads
- Controlled size in the low µm range
- Narrow size distribution
- Homogeneous encoding with molecular and nanoscale luminophores (dyes , QDs, platelets etc.)
- Sufficient fluorescence
- Easy, accessible procedure
T2 - GrK Nanohybrid Conference
CY - Hamburg, Germany
DA - 04.10.2022
KW - Polymerization
KW - Nanocrystals
KW - Fluorescence
KW - Microbeads
PY - 2022
AN - OPUS4-56028
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Billimoria, K.
A1 - Diaz Fernandez, Y. A.
A1 - Andresen, Elina
A1 - Sorzabal-Bellido, I.
A1 - Huelga-Suarez, G.
A1 - Bartczak, D.
A1 - Ortiz de Solórzano, C.
A1 - Resch-Genger, Ute
A1 - Goenaga Infante, H.
T1 - The potential of bioprinting for preparation of nanoparticle-based calibration standards for LA-ICP-ToF-MS quantitative imaging
N2 - This paper discusses the feasibility of a novel strategy based on the combination of bioprinting nano-doping technology and laser ablation-inductively coupled plasma time-of-flight mass spectrometry analysis for the preparation and characterization of gelatin- based multi-element calibration standards suitable for quantitative imaging. To achieve this, lanthanide up-conversion nanoparticles were added to a gelatin matrix to produce the bioprinted calibration standards. The features of this bioprinting approach were com- pared with manual cryosectioning standard preparation, in terms of throughput, between batch repeatability and elemental signal homogeneity at 5 μm spatial resolution. By using bioprinting, the between batch variability for three independent standards of the same concentration of 89 Y (range 0–600 mg/kg) was reduced to 5% compared to up to 27% for cryosectioning. On this basis, the relative standard deviation ( RSD ) obtained between three independent calibration slopes measured within 1 day also reduced from 16% (using cryosectioning ) to 5% (using bioprinting), supporting the use of a single standard preparation replicate for each of the concentrations to achieve good calibration performance using bioprinting. This helped reduce the analysis time by approximately 3-fold. With cryosectioning each standard was prepared and sectioned individually, whereas using bio-printing it was possible to have up to six different standards printed simultaneously, reducing the preparation time from approximately 2 h to under 20 min (by approxi- mately 6-fold). The bio-printed calibration standards were found stable for a period of 2 months when stored at ambient temperature and in the dark.
KW - Environmental analysis
KW - LA-ICP-MS
KW - Lanthanide
KW - Tag
KW - Fluorescence
KW - Nanoparticles
KW - Reference material
KW - Quality assurance
KW - 3D-printing
KW - Synthesis
KW - Production
KW - Multimodal
PY - 2022
DO - https://doi.org/10.1093/mtomcs/mfac088
SN - 1756-591X
VL - 14
IS - 12
SP - 1
EP - 9
PB - Oxford University Press
CY - Oxford
AN - OPUS4-57018
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Biophotonics and analytics - Photoluminescence properties of nanocrystals and surface group analysis
N2 - Correlating the photoluminescence (PL) properties of nanomaterials like semiconductor nanocrystals (QDs) and upconversion nanocrystals (UCNPs) assessed in ensemble studies and at the single particle level and studying their surface chemistry is increasingly relevant for applications of these nanomaterials in the life and material sciences. Here we present a comparison of the spectroscopic properties of ensembles and single nanocrystalline emitters and simple methods for the quantification of functional groups and ligands on particle surfaces. The overall goal of this study was to derive particle architectures and surface chemistries well suited for spectroscopic and microscopic applications.
T2 - Institutskolloqium Jozef Stefan Institute
CY - Ljubljana, Slovenia
DA - 07.11.20218
KW - Lanthanide
KW - Nanoparticle
KW - Nanocrystal
KW - Upconversion
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Modeling
KW - Photophysics
KW - Size
KW - Cleavable probe
PY - 2018
AN - OPUS4-46578
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CHAP
A1 - Resch-Genger, Ute
ED - Schäferling, Michael
T1 - Luminescent nanoparticles for chemical sensing and imaging
N2 - The implementation of fluorescent methods is of outstanding importance in the field of optical chemical sensor Technology and biosciences. Their bioanalytical applications are manifold including fluorescence microscopy, fluorescence in situ hybridization, DNA sequencing, fluorescence-activated cell sorting, immunoassays, analysis of DNA and Protein microarrays, and quantitative PCR, just to name a few examples. Particularly, fluorescence microscopy is a valuable method in the versatile field of biomedical imaging methods which nowadays utilizes different fluorescence Parameters like emission wavelength/Color and lifetime for the discrimination between different targets. Sectional Images are available with confocal microscopes. Tissue, cells or single cellular compartments can be stained and visualized with fluorescent dyes and biomolecules can be selectively labeled with fluorescent dyes to Monitor biomolecular interactions inside cells or at Membrane bound receptors.
On the other hand , fluorophores can act as indicator (or "molecular probe") to visualize intrinsically colorless and non-fluorescent ionic and neutral analytes such as pH, Oxygen (pO2), metal ions, anions, hydrogen peroxide or bioactive small organic molecules such as Sugars or nucleotides. Thereby, their photoluminescent properties (fluorescence or phoporescence intensity, exitation and/or Emission wavelength, emission lifetime or anisotropy) respond to the presence of these species in their immediate Environment. In general, the use of luminescent probes has the advantage that they can be delivered directly into the sample, and detected in a contactless remote mode. By now, these probes are often encapsulated in different types of nanoparticles (NPs) made from (biodegradable) organic polymers, biopolymers or inorganic materials like silica or bound to their surface.
KW - Fluorescence
KW - Upconversion
KW - NIR
KW - Sensor
KW - Nanoparticle
KW - Surface chemistry
KW - Quantum yield
KW - Liftetime
KW - Nanocrystal
KW - Lanthanide
KW - Semiconductor
KW - Polymer
KW - Silica
KW - Imaging
KW - Application
KW - Dye
KW - Quantum dot
PY - 2017
SN - 978-3-319-48260-6
SN - 978-3-319-48259-0
DO - https://doi.org/10.1007/978-3-319-48260-6_5
SN - 1573-8086
SP - 71
EP - 109
PB - SPRINGER INTERNATIONAL PUBLISHING AG
CY - Cham, Schweiz
AN - OPUS4-44011
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zavoiura, Oleksandr
A1 - Resch-Genger, Ute
A1 - Seitz, Oliver
T1 - Quantum dot-PNA conjugates for target-catalyzed RNA detection
N2 - Detection of pathogenic nucleic acids remains one of the most reliable approaches for the diagnosis of a broad range of diseases. Current PCR-based methods require experienced personnel and cannot be easily used for point-of care diagnostics, making alternative strategies for the sensitive, reliable, and cost-efficient detection of pathogenic nucleic acids highly desirable. Here, we report an enzyme-free method for the fluorometric detection of RNA that relies on a target-induced fluorophore transfer onto a semiconductor quantum dot (QD), uses PNA probes as selective recognition elements and can be read out with simple and inexpensive equipment. For QD-PNA conjugates with optimized PNA content, limits of detection of dengue RNA in the range of 10 pM to 100 nM can be realized within 5 h in the presence of a high excess of noncomplementary RNA.
KW - FRET
KW - Fluorescence
KW - DNA
KW - Assay
KW - Quantum dot
KW - Nano
KW - Particle
KW - Synthesis
KW - Ligation Assay
PY - 2018
DO - https://doi.org/10.1021/acs.bioconjchem.8b00157
SN - 1043-1802
VL - 29
IS - 5
SP - 1690
EP - 1702
PB - ACS Publications
AN - OPUS4-45120
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Characterization of nanocrystalline particles with NIR emission - Spectroscopic properties and surface group analysis
N2 - There is an increasing interest in optical reporters like semiconductor quantum dots and upconversion nanocrystals with emission > 800 nm for bioanalysis, medical diagnostics, and safety barcodes. Prerequisites for the comparison of material performance, the mechanistic understanding of nonradiative decay channels, and the rational design of new nanomaterials with improved properties are reliable fluorescence measurements and validated methods for the assessment of their surface chemistry. The latter is of special relevance for nanocrystalline emitters, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Here, we present the design of integrating sphere setups for the excitation power density-dependent absolute measurement of emission spectra and photoluminescence quantum yields in the wavelength region of 350 to 1600 nm and results from spectroscopic studies of semiconductor quantum dots and upconversion nanocrystals of different size and surface chemistries in various environments. Subsequently, examples for simple approaches to surface group and ligand analysis are presented.
T2 - 1st International Biophotonics Conference
CY - Singapure
DA - 25.07.2016
KW - Fluorescence
KW - Integrating sphere spectroscopy
KW - Quantum yield
KW - NIR
KW - IR
KW - Optical spectroscopy
KW - Nanomaterials
KW - Semiconducor nanocrystals
KW - Surface analysis
KW - Ligand analysis
KW - Optical assay
PY - 2016
AN - OPUS4-36998
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Guhrenz, C.
ED - Sayevich, V.
ED - Weigert, Florian
ED - Hollinger, E.
ED - Reichhelm, A.
ED - Gaponik, N.
ED - Eychmüller, A.
T1 - Transfer of Inorganic-Capped Nanocrystals into Aqueous Media
N2 - We report on a novel and simple approach to surface ligand design of CdSe-based nanocrystals (NCs) with biocompatible, heterobifunctional polyethylene glycol (PEG) molecules. This method provides high transfer yields of the NCs into aqueous media with preservation of the narrow and symmetric emission bands of the initial organic-capped NCs regardless of their interior crystal structure and surface chemistry. The PEG-functionalized NCs show small sizes, high photoluminescence quantum yields of up to 75%, as well as impressive optical and colloidal stability. This universal approach is applied to different fluorescent nanomaterials (CdSe/CdS, CdSe/CdSCdxZn1-xS, and CdSe/CdS/ZnS), extending the great potential of organic-capped NCs for biological applications.
KW - Fluorescence
KW - Ligand exchange
KW - Quantum dot
KW - Surface chemistry
KW - Semiconductor nanocrystal
KW - Quantum yield
KW - Lifetime
KW - Dispersibillity
KW - Colloid
PY - 2017
DO - https://doi.org/10.1021/acs.jpclett.7b02319
VL - 8
IS - 22
SP - 5573
EP - 5578
PB - The Journal of Physical Chemistry Letters
AN - OPUS4-43377
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Recent insights in the spectroscopic properties of upconversion nanoparticles
N2 - Lanthanide-doped up-converting nanoparticles (UCNPs) are promising reporters for medical diagnostics and bioimaging, which are excited in the near infrared (NIR) by multiphoton absorption processes, and show multiple narrow emission bands in the visible (vis) and NIR, long luminescence lifetimes in the μs range, and excellent photostability. Current limitations present their relative low absorption cross sections and low fluorescence efficiencies, with the latter being affected by particle size, surface chemistry, and microenvironment, particularly water.
Here, we present results from systematic studies of the excitation power density dependent upconversion luminescence spectra, intensities/intensity ratios of the individual emission bands, slope factors, and quantum yields of UCNPs of varying size, dopant concentration, and surface chemistry in different microenvironments as well as the up- and downconversion luminescence decay kinetics of the different emission bands. Moreover, first studies of the energy transfer from UCNPs to surface-bound organic dyes acting as fluorescence acceptors are shown. Based upon these measurements, fluorescence deactivation channels are identified and spectroscopic parameters for the screening of material performance are derived.
T2 - Spie Photonics west 2017
CY - San Francisco, USA
DA - 28.01.2017
KW - Upconverting nanoparticles
KW - Size
KW - FRET
KW - Fluorescence
KW - Absolute fluorescence quantum yield
KW - Fluorescence decay kinetics
KW - Power density dependence
PY - 2017
AN - OPUS4-39075
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Kage, Daniel
T1 - Stained microparticles for lifetime encoding - Flow cytometry application & photophysics
N2 - Multiparametric analyses involving optical techniques like flow cytometry are at the core of studying complex systems in biological research and diagnostic applications. However, for fluorescence-based techniques, the number of reporters distinguishable in spectral multiplexing is limited by spectral overlap and requires a multitude of excitation light sources and detection Systems. Intensity encoding often used for bead assays suffers from problems regarding dye concentration control and excitation light intensity fluctuations. An alternative is luminescence lifetime encoding, particularly to minimize instrument costs.
Here, we report on dye-stained polymer microparticles for lifetime encoding in flow cytometry with different organic dyes. This ranges from studies of the impact of parameters like dye loading concentration and particle diameter on fluorescence decay behavior to the demonstration of lifetime code reading and simultaneous ligand fluorescence signal detection with single-wavelength excitation in a flow.
T2 - DPG Spring Meeting 2017
CY - Dresden, Germany
DA - 19.03.2017
KW - Flow cytometry
KW - Fluorescence
KW - Life sciences
KW - Lifetime encoding
KW - Polymer particles
PY - 2017
AN - OPUS4-40056
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Choi, Youungeun
A1 - Kotthoff, Lisa
A1 - Olejko, L.
A1 - Resch-Genger, Ute
A1 - Bald, Ilko
T1 - DNA origami-based Förster resonance energy-transfer nanoarrays and their application as ratiometric sensors
N2 - DNA origami nanostructures provide a platform where dye molecules can be arranged with nanoscale accuracy allowing to assemble multiple fluorophores without dye–dye aggregation. Aiming to develop a bright and sensitive ratiometric sensor system, we systematically studied the optical properties of nanoarrays of dyes built on DNA origami platforms using a DNA template that provides a high versatility of label choice at minimum cost. The dyes are arranged at distances, at which they efficiently interact by Förster resonance energy transfer (FRET). To optimize array brightness, the FRET efficiencies between the donor fluorescein (FAM) and the acceptor cyanine 3 were determined for different sizes of the array and for different arrangements of the dye molecules within the array. By utilizing nanoarrays providing optimum FRET efficiency and brightness, we subsequently designed a ratiometric pH nanosensor using coumarin 343 as a pH-inert FRET donor and FAM as a pH-responsive acceptor. Our results indicate that the sensitivity of a ratiometric sensor can be improved simply by arranging the dyes into a well-defined array. The dyes used here can be easily replaced by other analyte-responsive dyes, demonstrating the huge potential of DNA nanotechnology for light harvesting, signal enhancement, and sensing schemes in life sciences.
KW - DNA origami
KW - FRET
KW - Sensing
KW - Ratiometric sensing
KW - Fluorescence
PY - 2018
DO - https://doi.org/10.1021/acsami.8b03585
SN - 1944-8244
SN - 1944-8252
VL - 10
IS - 27
SP - 23295
EP - 23302
PB - ACS
AN - OPUS4-46002
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Mousavi, M.
ED - Thomasson, B.
ED - Li, M.
ED - Kraft, Marco
ED - Würth, Christian
ED - Andersson-Engels, S.
T1 - Beam-profile-compensated quantum yield measurements of upconverting nanoparticles
N2 - The quantum yield is a critically important parameter in the development of lanthanide-based upconverting nanoparticles (UCNPs) for use as novel contrast agents in biological imaging and optical reporters in assays. The present work focuses on the influence of the beam Profile in measuring the quantum yield (f) of nonscattering dispersions of nonlinear upconverting probes, by establishing a relation between f and excitation light power density from a rate equation analysis. A resulting 60% correction in the measured f due to the beam profile utilized for excitation underlines the significance of the beam profile in such measurements, and its impact when comparing results from different Setups and groups across the world.
KW - Fluorescence
KW - Lanthanide
KW - Upconversion
KW - Brithtness
KW - Quantification
KW - Nanoparticle
KW - Absolute fluoreometry
KW - NIR
KW - IR
KW - Quantum yield
KW - Integrating sphere spectroscopy
KW - Method
PY - 2017
DO - https://doi.org/10.1039/c7cp03785f
SN - 1463-9076
SN - 1463-9084
VL - 19
IS - 33
SP - 22016
EP - 22022
PB - Royal Society of Chemistry
AN - OPUS4-42583
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Kage, Daniel
T1 - Time domain flow cytometry utilizing lifetime-encoded polymer microparticles
N2 - Flow cytometry is a widely used method in biological research and medical diagnostics. Depending on the respective application, two opposing directions of development are currently of interest. On the one hand, there is a need for analyses of growing complexity employing more and more fluorescent labels and codes. On the other hand, cost-effective methods and portable, miniaturized, and robust instruments are desired.
Commonly performed spectral multiplexing utilizing a color code suffers from several problems, such as the sensitivity of fluorescence intensity measurements to fluctuations in excitation light intensity and dye concentration and hence, photobleaching, dye leaking for certain encoding procedures, and spectral crosstalk, limiting the achievable number of detection channels. Moreover, it typically requires several costly excitation light sources. An innovative alternative can be lifetime multiplexing and the discrimination between different encoding fluorophores and carrier beads based on their fluorescence decay kinetics. In order to examine the potential of this approach, dye encoded beads (lifetime encoded surface chemistry) were prepared using several fluorophores from different dye classes and their suitability for lifetime discrimination in a flow was tested in conjunction with a custom designed flow cytometer equipped with a pulsed light source and a fast detector.
In a first step, the spectroscopic properties of micrometer-sized dye-stained PMMA beads were studied by means of steady state and time-resolved photoluminescence measurements. For the performance of studies on the practical use of these microbeads in flow cytometry applications, a custom-built demonstrator model for a flow system was employed.
Our results demonstrated that lifetime discrimination and simultaneous readout of a ligand fluorescence signal for analyte quantification with a set of dye-stained polymer microbeads at single wavelength excitation is feasible. These studies are expected to pave the road for new applications of fluorescence lifetime multiplexing within the framework of time-domain flow cytometry and bead-based assays.
T2 - ANAKON 2017
CY - Tübingen, Germany
DA - 03.04.2017
KW - Flow cytometry
KW - Fluorescence
KW - Life sciences
KW - Lifetime encoding
KW - Polymer particles
PY - 2017
AN - OPUS4-39995
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Simple methods, validation concepts, and reference materials for the characterization of functional nanomaterials and microparticles
N2 - The surface chemistry / functionalization of nanomaterials and microparticles largely controls the stability of these materials as well as their solubility and subsequent biofunctionalization and their interactions with biological systems. Moreover, in the case of some nanomaterials like semiconductor quantum dots or lanthanide-based upconversion nanocrystals, the ligand shell strongly affects their optical properties, e.g., via passivation of surface states and traps that favor luminescence quenching or the protection of surface atoms from quenching water molecules. This renders analytical methods for the quantification of surface groups like functionalities very important. Targets of broad interest are here amino, carboxyl, alkine and maleimide groups used for common bioconjugation reactions and typical ligands like thiols and polyethylene glycol (PEG) molecules of varying length, used for the tuning of material hydrophilicity and biocompatibility, minimization of unspecific interactions, prevention of biofouling, and enhancement of blood circulation times as well as surface-bound biomolecules like streptavidin or other biomolecules relevant e.g., for diagnostic assays. Here, we focus on simple optical methods relying on standard laboratory instrumentation, validated by method comparison and/or mass balances and present examples for their use for the characterization of different types of nanomaterials and microparticles.
T2 - Innovationsforum Senftenberg
CY - Senftenberg, Germany
DA - 01.06.2016
KW - Surface chemistry
KW - Functional group analysis
KW - Thiol assay
KW - Fluorescence
KW - Nanomaterial
KW - Nanoparticle
KW - PEG
KW - Ligand
KW - Semiconductor quantum dot
KW - Quantum yield
KW - Quantification
KW - Method validation
KW - Integrating sphere spectroscopy
KW - Fluorescence standard
PY - 2016
N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N.
AN - OPUS4-37111
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Kage, Daniel
T1 - FLiMFlow – Recent achievements in flow cytometry with lifetime detection and lifetime-encoded beads
N2 - Flow cytometry is a widespread technique in biological research and clinical applications. Two different directions are currently of importance in development of new methods in this field. Whereas analyses in research become increasingly complex and require a growing number of simultaneously detectable codes and fluorescent labels, also low-cost methods and portable devices are needed in routine application.
Lifetime encoding could present an alternative to common spectral multiplexing. On the one hand, it addresses the need for additional codes by combining spectral and lifetime multiplexing. On the other hand, using only lifetime encoding could help to reduce instrument costs by keeping the number of excitation sources and detectors low.
Here, we report on our recent progress in employing dye-stained lifetime-encoded polymer microparticles as a model system for lifetime encoding in flow cytometry. The discrimination of two lifetime codes was achieved with two bead sets. Moreover, the simultaneous detection of a spectrally different ligand fluorescence signal could be demonstrated.
T2 - FLiMFlow meeting
CY - Pisa, Italy
DA - 28.09.2016
KW - Flow cytometry
KW - Fluorescence
KW - Life sciences
KW - Lifetime encoding
KW - Polymer particles
PY - 2016
AN - OPUS4-38239
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Wang, Cui
ED - Otto, S.
ED - Dorn, M.
ED - Kreidt, E.
ED - Lebon, J.
ED - Srsan, L.
ED - di Martino-Fumo, P.
ED - Gerhards, M.
ED - Seitz, M.
ED - Heinze, K.
T1 - Deuterierter molekularer Rubin mit Rekord-Lumineszenzquantenausbeute
N2 - Der kürzlich publizierte Chrom(III)-Komplex 13+([Cr(ddpd)2]3+) zeigt in wässriger Lösung unter Umgebungsbedingungen eine bemerkenswert starke Emission im nahen Infrarot-Bereich mit einer Emissionswellenlänge von 775 nm.
Geschicktes Ligandendesign verhindert strahlungslose Desaktivierungsprozesse wie Photosubstitution, Rück-Intersystem-Crossing und trigonale Verzerrungen und führt damit zu einer Phosphoreszenzlebensdauer im Bereich von Mikrosekunden.
In Abwesenheit von Energieakzeptoren wie molekularem Sauerstoff verbleibt nur Energietransfer zu hochenergetischen Oszillatoren der Liganden und Lösungsmittelmoleküle wie beispielsweise OH- und CH-Streckschwingungen als Desaktivierungspfad. Selektive Deuterierung der ddpd-Liganden und der Lösungsmittel l-sst die Effizienz dieser Oszillatoren bei der Desaktivierung angeregter Zustände erkennbar werden. Gezieltes Ausschalten dieser Relaxationspfade führt zu einer Quantenausbeute von 30% und einer Lebensdauer von 2.3 Millisekunden bei Raumtemperatur in Lösung – Rekordwerte für einen Komplex, der auf dem Element Chrom basiert. Diese fundamentalen Erkenntnisse ebnen den Weg für gezieltes Ligandendesign zur Synthese lumineszierender Komplexe mit gut verfügbaren Übergangsmetallen.
KW - Fluorescence
KW - Quantum yield
KW - Ligand design
KW - Cr(III)
KW - Complex
KW - Oxygen sensor
KW - NIR
KW - Fluorescence lifetime
PY - 2018
DO - https://doi.org/10.1002/ange.201711350
SN - 1521-3757
VL - 130
IS - 4
SP - 1125
EP - 1130
PB - Wiley-VCH Verlag & Co. KGaA
CY - Weinheim
AN - OPUS4-44043
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Wegner, Karl David
T1 - Luminescent Quantum dots – the next-generation nano light bulbs
N2 - Fluorescent semiconductor nanocrystals, also known as quantum dots (QDs), enabled many advancements in biotechnology, photovoltaics, photocatalysis, quantum computing and display devices. The high versatility of this nanomaterial is based on their unique size-tunable photoluminescence properties, which can be adjusted from the visible to the near-infrared range. In contrast to other nanomaterials, QDs made the transition from a laboratory curiosity to the utilization in commercial products, like the QLED television screen or in smartphone displays. The best investigated QDs are composed of heavy metals like cadmium or lead, which is not the best choice in terms of toxicity and environmental pollution. A more promising material is Indium Phosphide (InP), which is also currently used by Samsung, Sony and co. in the QLED displays.
In this contribution, I would like to give you a sneak peek behind the curtains of nanomaterial synthesis and show how this material is produced, how to stabilize their structural properties, and assess their toxicity in environmentally relevant conditions. Furthermore, I would like to present a synthesis method to accomplish the last open challenge in display technology of a blue luminescent LED based on QDs by introducing a new element to the InP QDs.
T2 - The Berlin Postdoc Day
CY - Berlin, Germany
DA - 03.11.2022
KW - InP
KW - Quantum dots
KW - Fluorescence
KW - Aging
KW - Doping
KW - Nanomaterial
KW - Cytotoxicity
PY - 2022
AN - OPUS4-56194
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Semiconductor nanocrystals with VIS and NIR/IR emission - spectroscopy properties and surface chemistry
N2 - Semiconductor nanocrystals with a spherical (QDs) core and a spherical or a rod-shaped Shell, u.a., so-called Quantum dot-Quantum rods (QDQRs) are increasingly used as fluorescent Reporters or optically active components in the life and material science, e.g., in solid state lightening including Plasma Displays. (1,2) Morever, there is an increasing interest in materials with emission >800 nm for bioanalysis, medical diagnostics, and safety barcodes. Prerequisites for the mechanistic understanding of nonradiativ decay channels needed for the rational design of improved nanomaterials and the comparison of material Performance are reliable fluorescence measurements and validated methods for the assessment of their surface chemistry. (3,4) The latter is of particular importance for nanocrystalline Emitters, where surface states and the accessibility of emissive states by quenchers largely control photoluminescence properties. (5) Here, we present results from systematic spectroscopic studies including absolutely measured photolumunescence Quantum yields of different vissible and NIR emisisve QD and QDQRs Systems of varying particle architecture size and surface chemistries in Dispersion and embedded in salt crystals. (6,7)
T2 - MCare 2017
CY - Jeju, South Korea
DA - 20.02.2017
KW - Semiconductor quantum dot
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Photophysics
KW - Quantum yield
KW - Single particle
PY - 2017
AN - OPUS4-43133
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Wegner, Karl David
T1 - Exploring the photoluminescence of gold NCs and Ag2S NPs to boost their SWIR emission
N2 - Current challenges and objectives for non-invasive optical bioimaging are deep tissue penetration, high detection sensitivity, high spatial and temporal resolution, and fast data acquisition. A promising spectral window to tackle these challenges is the short-wave infrared (SWIR) ranging from 900 nm to 1700 nm where scattering, absorption, and autofluorescence of biological components are strongly reduced compared to the visible/NIR. At present, the best performing SWIR contrast agents are based on nanomaterials containing toxic heavy-metal ions like cadmium or lead, which raises great concerns for biological applications. Promising heavy-metal free nanoscale candidates are gold nanoclusters (AuNCs) and Ag2S nanoparticles (NPs). The photoluminescence (PL) of both types of nanomaterials is very sensitive to their size, composition of their surface ligand shell, and element composition, which provides an elegant handle to fine-tune their absorption and emission features and boost thereby the size of the signals recorded in bioimaging studies.
Aiming for the development of SWIR contrast agents with optimum performance, we dived deeper into the photophysical processes occurring in these nanomaterials, thereby exploring in depth how the environment, surface ligand composition, and the incorporation of transition metals influence the optical properties of AuNCs and Ag2S NPs. We observed a strong enhancement of the SWIR emission of AuNCs upon exposure to different local environments (in solution, polymer, and in the solid state). Addition of metal ions such as Zn2+ to Ag2S based NPs led to a strong PL enhancement, yielding PL quantum yields of about 10% and thus making them highly suitable for non-invasive deep imaging of vascular networks and 3D fluid flow mapping.
T2 - NaNaX 10 - Nanoscience with Nanocrystals
CY - Klosterneuburg, Austria
DA - 03.07.2023
KW - Quantum dots
KW - Ag2S
KW - Fluorescence
KW - SWIR
KW - Gold nanocluster
KW - Nanomaterial
KW - bioimaging
PY - 2023
AN - OPUS4-58104
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Huang, K.
A1 - Liu, H.
A1 - Kraft, Marco
A1 - Shikha, S.
A1 - Zheng, X.
A1 - Agren, H.
A1 - Würth, Christian
A1 - Resch-Genger, Ute
A1 - Zhang, Y.
T1 - A protected excitation-energy reservoir for efficient upconversion luminescence
N2 - Lanthanide-doped upconversion nanoparticles (UCNPs) are of great interest for biomedical applications. Currently, the applicability of UCNP bionanotechnology is hampered by the generally low luminescence intensity of UCNPs and inefficient energy Transfer from UCNPs to surface-bound chromophores used e.g. for photodynamic therapy or analyte sensing. In this work, we address the low-Efficiency issue by developing versatile core-Shell nanostructures, where high-concentration sensitizers and activators are confined in the core and Shell Region of representative hexagonal NaYF2:Yb,Er UCNPs. After Doping concentration optimization, the sensitizer-rich core is able to harvest/accumulate more excitation energy and generate almost one order of Magnitude higher luminescence intesity than conventional homogeneously doped nanostructures. At the same time, the activator Ions located in the Shell enable a ~6 times more efficient resonant energy Transfer from UCNPs to surface-bound acceptor dye molecules due to the short distance between donor-acceptor pairs. Our work provides new insights into the rational design of UCNPs and will greatly encrease the General applicability of upconversion nanotechnologies.
KW - Fluorescence
KW - Lanthanide
KW - Upconversion
KW - Brightness
KW - Quantification
KW - Nanoparticle
KW - Absolute fluorometry
KW - NIR
KW - IR
KW - Quantum yield
KW - Integrating sphere spectroscopy
KW - Method
KW - Energy transfer
KW - Shell
KW - Particle architecture
PY - 2017
DO - https://doi.org/10.1039/c7nr06900f
SN - 2040-3372
SN - 2040-3364
VL - 10
IS - 1
SP - 250
EP - 259
PB - The Royal Society of Chemistry
AN - OPUS4-43893
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Standardization of fluorescence measurements: Design, development, validation, and fabrication of format-adaptable fluorescence standards for intensity, spectral, and temporal quantities
N2 - Photoluminescence techniques are amongst the most widely used tools in the material and life sciences, with new and exciting applications continuously emerging, due to their many advantages like comparative ease of use, unique sensitivity, non-invasive character, and potential for multiplexing, remote sensing, and miniaturization. Drawbacks are , however, signals, that contain unwanted wavelength- and polarization contributions from instrument-dependent effects, which are time-dependent due to the aging of instrument components, and difficulties to measure absolute fluorescence intensities. Thus, there is a considerable need for standards for intensity, spectral, and temporal fluorescence quantities to meet the increasing need for instrument performance validation and global trends to harmonize physicochemical measurements. In this respect, instrument calibration strategies together with different types of fluorescence standards are presented as well as design concepts for robust, easy-to-use, and format-adaptable fluorescence standards useable for the determination of different fluorescence parameters and a broad variety of fluorescence techniques.
T2 - SALSA-Kolloquien
CY - Berlin, Germany
DA - 07.06.2016
KW - Fluorescence
KW - Standard
KW - Quality assurance
KW - Spectral correction
KW - Quantum yield
PY - 2016
AN - OPUS4-37070
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Quantitative Characterization of Functional Nanomaterials with vis/NIR Emission
N2 - The rational design of functional nanomaterials for optical applications in the material and life sciences requires optical-spectroscopic methods for the quantitative characterization of their signal-relevant optical properties. Additionally, methods for the simple and quantitative analysis of the surface chemistry are desired as the chemical nature and number of the surface groups and ligands can affect the optical features and controls the interaction of these nanomaterials with their environment. Here, we present quantitative photoluminescenvce studies of different types of vis/NIR-emissive nanomaterials like semiconductor quantum dots and upconversion nanocrystals will be presented and their relevance for the mechanistic understanding of nonradiative decay channels and the rational design of new nanomaterials will be underpinned. In this respect, also validation concepts for such measurements and absolute fluorometry will be introduced. In addition, the potential of optical spectroscopy for surface group and ligand analysis surface chemistry will be demonstrated exemplarily for semiconductor quantum dots
T2 - AK Prof. Voss
CY - Uni Brunswick, Germany
DA - 03.08.2017
KW - Semiconductor
KW - Upconversion
KW - Nanoparticle
KW - Fluorescence
KW - Surface group analysis
KW - NIR
KW - Absolute fluoreometry
KW - Integrating sphare spectroscopy
KW - Optical probe
KW - Assay
KW - Thiol ligand
PY - 2017
N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N.
AN - OPUS4-41366
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Characterization of dye-protein conjugates with optical methods
N2 - Fluorophore labeled proteins and antibodies, referred to also as targeted optical probes, present a promising strategy for a variety of applications from fundamental cell-based biological studies to in vivo diagnostics and image guided surgeries in humans. In this respect, design strategies for the preparation of such conjugates from different dyes including analyte-responsive fluorophores are presented as well as their analytical and spectroscopic characterization employing Absorption spectroscopy and steady state and time-resolved fluorometry. Special emphasis is dedicated to the influence of dye hydrophilicity and labeling density on the optical properties and binding behavior of these dye-bioconjugates including their performance in in vitro and in vivo bioimaging studies.
T2 - International Workshop “Affinity - Mass spectrometry – New Methods and Application to Protein Therapeutics Development”
CY - Rüsselsheim am Main, Germany
DA - 14.11.2016
KW - Fluorescence
KW - Dye bioconjugates
KW - Protein
KW - Immunoassay
KW - Quality assurance
KW - Optical characterization
KW - Dye
KW - NIR
KW - Imaging
PY - 2016
AN - OPUS4-38504
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Pauli, J.
A1 - Güttler, Arne
A1 - Schneider, T.
A1 - Würth, Christian
A1 - Resch-Genger, Ute
T1 - Fluorescence Quantum Yield Standards for the UV/Visible/NIR: Development, Traceable Characterization, and Certification
N2 - The rational design of next generation molecular and nanoscale reporters and the comparison of different emitter classes require the determination of the fluorometric key performance parameter fluorescence quantum yield (Φf), i.e., the number of emitted photons per number of absorbed photons. Main prerequisites for reliable Φf measurements, which are for transparent luminophore solutions commonly done relative to a reference, i.e., a fluorescence quantum yield standard of known Φf, are reliable and validated instrument calibration procedures to consider wavelength-, polarization-, and time-dependent instrument specific signal contributions, and sufficiently well characterized fluorescence quantum yield standards. As the standard’s Φf value directly contributes to the calculation of the sample’s Φf, its accuracy presents one of the main sources of uncertainty of relative Φf measurements. To close this gap, we developed a first set of 12 fluorescence quantum yield standards, which absorb and emit in the wavelength region of 330−1000 nm and absolutely determined their Φf values with two independently calibrated integrating sphere setups.
Criteria for standard selection and the configuration of these novel fluorescence reference materials are given, and the certification procedure is presented including homogeneity and stability studies and the calculation of complete uncertainty budgets for the certified Φf values. The ultimate goal is to provide the community of fluorescence users with available reference materials as a basis for an improved comparability and reliability of quantum yield data since the measurement of this spectroscopic key property is an essential part of the characterization of any new emitter.
KW - Optical spectroscopy
KW - Traceability
KW - Reference product
KW - Dye
KW - Fluorescence
KW - Quantum yield
KW - Reference material
KW - Reference data
KW - Certification
KW - Quality assurance
PY - 2023
DO - https://doi.org/10.1021/acs.analchem.2c05530
VL - 95
SP - 5671
EP - 5677
PB - American Chemical Society
AN - OPUS4-58151
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Tavernaro, Isabella
T1 - Development of amorphous silica particle based reference materials for surface functional group quantification
N2 - Functionalized nanomaterials (NM) with their unique size-dependent properties are of increasing relevance for current and future developments in various fields such as medical and pharmaceutical industry, computing, electronics or food and consumer products. The performance and safety of NM are determined by the sum of their intrinsic physicochemical properties.1 Besides other key parameters, the particle surface chemistry, which is largely controlled by the chemical nature and density of functional groups and ligands, must be considered for a better performance, stability, and processibility of NM, as well as their interaction with the environment. Thus, particle standards with well-designed surfaces and methods for functional group quantification can foster the sustainable development of functional and safe(r) NM.2 Here we provide a brief overview of the ongoing research in division Biophotonics to design tailored amorphous silica reference particles with bioanalytically relevant functional groups and ligands, for the development of standardized and validated surface functional group quantification methods.
T2 - Workshop NanoRiskSD project
CY - Berlin, Germany
DA - 09.06.2022
KW - Nanoparticle
KW - Surface analysis
KW - Silica
KW - Fluorescence
KW - Assay
PY - 2022
AN - OPUS4-55004
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kraft, Marco
A1 - Würth, Christian
A1 - Muhr, V.
A1 - Hirsch, T.
A1 - Resch-Genger, Ute
T1 - Explaining the influence of dopant concentration and excitation power density on the luminescence and brightness of beta-NaYF_4:Yb~(3+),Er~(3+) nanoparticles: Measurements and simulations
N2 - A systematic study of the luminescence properties of monodisperse β-NaYF4: 20% Yb3+, 2% Er3+ upconversion nanoparticles (UCNPs) with sizes ranging from 12–43 nm is presented utilizing steady-state and time-resolved fluorometry.
Special emphasis was dedicated to the absolute quantification of size- and environment-induced quenching of upconversion luminescence (UCL) by highenergy O–H and C–H vibrations from solvent and ligand molecules at different excitation power densities (P). In this context, the still-debated Population pathways of the 4F9/2 energy level of Er3+ were examined. Our results highlight the potential of particle size and P value for color tuning based on the pronounced near-infrared emission of 12 nm UCNPs, which outweighs the red Er3+ emission under “strongly quenched” conditions and accounts for over 50% of total UCL in water. Because current rate equation models do not include such emissions, the suitability of these models for accurately simulating all (de)population pathways of small UCNPs must be critically assessed. Furthermore, we postulate population pathways for the 4F9/2 energy level of Er3+, which correlate with the size-, environment-, and P-dependent quenching states of the higher Er3+ energy levels.
KW - Nanoparticle
KW - Nanosensor
KW - Fluorescence
KW - Upconversion
KW - Upconversion nanoparticle
KW - NIR
KW - Photophysics
KW - Lanthanide
KW - Size
KW - Surface chemistry
KW - Quantum yield
KW - Mechanism
KW - Lifetime
KW - Decay kinetics
KW - Quenching
KW - Diameter
KW - Cyclohexane
KW - Water
PY - 2018
DO - https://doi.org/10.1007/s12274-018-2159-9
VL - 11/12
SP - 6360
EP - 6374
PB - Springer Nature
AN - OPUS4-50307
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Challenges and examples for quantitative fluorescence measurements > 800 nm with semiconductor and lanthanide-doped nanocrystals
N2 - There is an increasing interest in molecular and nanoscale with emission > 800 nm and recently also > 1000 nm for bioanalysis, medical diagnostics, bioimaging, and safety barcodes. Mandatory for the comparison of different emitter classes and the rational design of the next generation of reporters for the short wavelength infrared (SWIR) Region are reliable and quantitative photoluminescence measurements in this challenging wavelength region. This is of special relevance for nanocrystalline emitters like semiconductor quantum dots and rods as well as lanthanide-based upconversion and downconversion nanocrystals, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Such measurements are currently hampered by the lack of suitable methods and standards for instrument calibration and validation and quantum yield standards with emission > 800 nm and especially > 1000 nm.
In this respect, we present the design of integrating sphere setups for absolute and excitation power density-dependent measurements of emission spectra and photoluminescence quantum yields in the wavelength Region of 650 to 1650 nm including calibration strategies and first candidates for potential fluorescence standards.
Subsequently, the photoluminescence properties of different types of nanocrystals are presented including the upconversion and downconversion emission of differently sized and surface functionalized lanthanide-doped nanoparticles and photoluminescence quenching effects are quantified.
T2 - SHIFT 2017
CY - Teneriffa, Spain
DA - 13.11.2017
KW - Upconversion
KW - Nanoparticle
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Surface chemistry
KW - Deactivation pathways
KW - Semiconductor quantum dot
KW - SWIR
KW - Quantum yield
PY - 2017
AN - OPUS4-43203
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - The European Upconversion Network: From the Design of Photon-upconverting Nanomaterials to (Biomedical) Applications (CM1403) WG1 Materials Research & Photophysical Characterization
N2 - Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been in the focus of many research activities in the material and life sciences over the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. In order to fully exploit the application potential of these fascinating nanomaterials, a number of challenges has to be overcome such as the low brightness particularly of small UCNPs and the reliable quantification of the excitation power density (P)-dependent upconversion luminescence (UCL). Here, the need and requirements on the characterization of the optical properties of UCNPs are discussed with special focus on the reliabiliy and comparability of relative and quantitative luminescence measurements and prerequisites for their standardization.
T2 - COST Treffen
CY - Aveiro, Portugal
DA - 26.06.2017
KW - Upconversion
KW - Nanoparticle
KW - Fluorescence
KW - NIR
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - Reference maerial
KW - Standardization
KW - Quantum yield
PY - 2017
AN - OPUS4-41367
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Tavernaro, Isabella
T1 - Rational Design of Analyte-responsive Fluorescent Particle Sensors for Life Sciences Applications
N2 - Engineered and tailor-made nanomaterials (NM) are of increasing relevance for current and future developments in the life and material sciences for applications, e.g., as drug carriers, fluorescent sensors, and multimodal labels in bioanalytical assays, and reporters for imaging applications. For instance, NM-based reporters and sensors, that are labelled or stained with a multitude of conventional or sensor dyes, have several advantages as compared to molecular probes like enhanced brightness, i.e., amplified signals, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, this can enable the use of hydrophobic dyes in aqueous environments. For rational NM design, choosing and tailoring the intrinsic physicochemical properties, such as particle size, size distribution, morphology, and surface chemistry of the NM application-specific considerations like biocompatibility, ease and low cost of preparation, and colloidal stability and performance in the targeted environment must be considered. In this lecture, different design concepts of inorganic, organic, and hybrid NM and microparticles with hydrophilic surface chemistries and different functionalities are presented that can be used for the targeting of lysosomes; and to monitor functional parameters of endo-lysosomal compartments, like pH or enable oxygen sensing.
T2 - Chemical Probes for Lysosomal Biology
CY - York, United Kingdom
DA - 09.09.2024
KW - Luminescence
KW - Quantification
KW - Nano
KW - Particle
KW - Quality assurance
KW - Fluorescence
KW - Method
KW - Uncertainty
KW - Reference material
KW - Sensor
KW - Synthesis
KW - Dye
KW - pH
KW - Silica
KW - Polystyrene
KW - Surface analysis
PY - 2024
AN - OPUS4-62173
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Quantification of Surface Groups on Nanomaterials with Simple Optical Methods
N2 - Surface functionalization of nanomaterials is nowadays at the core of many applications of functional materials in the life and material sciences. Examples range from membranes and microarrays over bead-based assays, and next generation sequencing to nanometer-sized optical reporters, nanosensors, and magnetic and optical contrast agents. Typical function-nalization steps include silanization and grafting reactions with reactive monomers to introduce functional groups like amino or carboxylic acid groups or the attachment of ligands like polyethylene glycol (PEG) molecules and biomolecules. [1-3] This enables to tune e.g., dis-persibility, hydrophilicity and biocompatibility, minimize unspecific interactions, improve biofunctionalization efficiencies, and enhance blood circulation times and allows for the use of nanomaterials as reporters in assays or the design of targeted probes for bioimaging.
At the core of all functionalization strategies are reliable and validated methods for surface group and ligand quantification that can be preferably performed with routine laboratory instrumentation, require only small amounts of substances, and are suitable for many different types of nanomaterials. [3] There is meanwhile a considerable need to make these methods traceable. We present here versatile and simple concepts for the quantification of common functional groups, ligands, and biomolecules on different types of organic and inorganic nanomaterials, using conventional and newly developed cleavable and multimodal reporters, that can be detected with optical spectroscopy. [4-7] These reporters are chosen to enable method validation with the aid of method comparisons and mass balances. Also, strategies how to make these simple assays traceable to SI units using quantitative nuclear resonance spectroscopy (qNMR) and X-ray photoelectron spectroscopy (XPS) are derived.
T2 - JRC-NIST Workshop
CY - Ispra, Italy
DA - 04.12.2018
KW - Nanoparticle
KW - Nanocrystal
KW - Absolute fluorometry
KW - Fluorescence
KW - Surface chemistry
KW - Assay
KW - Cleavable probe
KW - Conductometry
KW - Quantification
KW - Functional group
PY - 2018
AN - OPUS4-46950
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - GEN
A1 - Scholtz, Lena
A1 - Resch-Genger, Ute
T1 - Behind the Paper - Dual color pH probes made from silica and polystyrene nanoparticles and their performance in cell studies
N2 - In this contribution we highlight the importance of comparison for scientific research while developing a new, functional pH sensor system, and the valuable insights this can provide.
KW - Dye
KW - Optical Spectroscopy
KW - pH probe
KW - Silica and Polystyrene Particles
KW - Nano
KW - Surface groups
KW - Safe-by-Design
KW - Cell studies
KW - Sensors
KW - Particle Synthesis
KW - Fluorescence
PY - 2023
UR - https://communities.springernature.com/posts/dual-color-ph-probes-made-from-silica-and-polystyrene-nanoparticles-and-their-performance-in-cell-studies
SP - 1
EP - 2
PB - Springer Nature
CY - London
AN - OPUS4-59150
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
A1 - Pauli, J.
A1 - Güttler, Arne
A1 - Richter, Maria
A1 - Fiedler, Saskia
A1 - Frenzel, Florian
A1 - Wegner, Karl David
A1 - Würth, Christian
T1 - Photoluminescence Quantum Yields of Luminescent Nanocrystals and Particles in the UV/vis/NIR/SWIR
N2 - The rational design of functional luminescent materials such as semiconductor quantum dots and lanthanide-based upconversion nanoparticles, all photophysical and mechanistic studies, and the comparison of different emitters require accurate and quantitative photoluminescence measurements. Particularly the reliable determination of the key performance parameter photoluminescence quantum yield (f), the number of emitted per absorbed photons, and the brightness are of special importance for luminescence applications in the life and material sciences and nano(bio)photonics.[1] In this context, examples for absolute measurements of the photoluminescence quantum yields of UV/vis/NIR/SWIR emissive semiconductor quantum dots and rods, made from different materials, and spectrally shifting lanthanide upconversion nanocrystals with different surface chemistries in transparent matrices are presented including excitation wavelength and power density dependent studies utilizing integration sphere spectroscopy.[2,3] In addition, procedures for the absolute determination of the photoluminescence quantum yields of scattering dispersions of larger size quantum rods and differently sized inorganic particles have been developed as well as procedures for the characterization of solid luminescent nanomaterials such as different perovskites and YAG:Cer converter materials.[4] Thereby, challenges and pitfalls of f measurements in different wavelength regions including the SWIR and material-specific effects related to certain emitter classes are addressed, achievable uncertainties are quantified, and relative and absolute measurements of photoluminescence quantum yield measurements are compared to underline limitations of the former approach. Finally, a set of novel UV/vis/NIR quantum yield standards is presented including their certification with a complete uncertainty budget.[5]
T2 - NANAX 10
CY - Klosterneuburg, Austria
DA - 03.07.2023
KW - Fluorescence
KW - Optical spectroscopy
KW - Reference data
KW - Traceability
KW - NIR
KW - Scattering
KW - Reference material
KW - Certification
KW - Quality assurance
KW - Dye
KW - Reference product
KW - SWIR
KW - Nano
KW - Particle
KW - Perovskite
KW - Integrating sphere spectroscopy
KW - Quantum yield
PY - 2023
AN - OPUS4-58238
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Scholtz, Lena
T1 - Luminescent Polymer Microbeads – Synthesis & Applications
N2 - Differently sized, luminescent polymer beads encoded with QDs were prepared with a simple, optimized polymerization procedure. The optical
properties of the resulting particles were studied to ensure sufficient fluorescence. In addition, possible future applications were identified.
T2 - Future WiNS: New Energies for a Sustainable World
CY - Berlin, Germany
DA - 07.12.2022
KW - Polymerization
KW - Quantum dots
KW - Fluorescence
KW - Luminescence
PY - 2022
AN - OPUS4-56560
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Potapkin, D. V.
A1 - Geißler, Daniel
A1 - Resch-Genger, Ute
A1 - Goryacheva, I. Y.
T1 - Fluorescent quantum dot hydrophilization with PAMAM dendrimer
N2 - Polyamidoamine (PAMAM) dendrimers were used to produce CdSe core/multi-shell fluorescent quantum dots (QDs) which are colloidally stable in aqueous solutions. The size, charge, and optical properties of QDs functionalized with the 4th (G4) and 5th (G5) generation of PAMAM were compared with amphiphilic polymer-covered QDs and used as criteria for the evaluation of the suitability of both water solubilization methods. As revealed by dynamic and electrophoretic light scattering (DLS and ELS), the hydrodynamic sizes of the QDs varied from 30 to 65 nm depending on QD type and dendrimer generation, with all QDs displaying highly positive surface charges, i.e., zeta potentials of around +50 mV in water. PAMAM functionalization yielded stable core/multi-shell QDs with photoluminescence quantum yields (Φ) of up to 45%. These dendrimer-covered QDs showed a smaller decrease in their Φ upon phase transfer compared with QDs made water soluble via encapsulation with amphiphilic brush polymer bearing polyoxyethylene/ polyoxypropylene chains.
KW - Photoluminescence quantum yield
KW - Quantum dots
KW - PAMAM dendrimers
KW - Phase transfer
KW - Fluorescence
PY - 2016
DO - https://doi.org/10.1007/s11051-016-3411-4
VL - 18
IS - 108
SP - 1
EP - 9
PB - Springer Science + Business Media B.V.
CY - Dordrecht, Netherlands
AN - OPUS4-35857
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Instrument Calibration and Standardization of Fluorescence Measurements in the UV/vis/NIR/IR
N2 - Comparison of fluorescence measurements performed on different fluorescence instruments, analyte quantification from fluorescence intensities as well as the determination of fluorescence quantum yields require instrument calibration and consideration of the wavelength-dependent instrument-specific quantities spectral photon flux reaching the sample and spectral responsivity. Here, we present guidelines and recommendations for the qualification of fluorescence instruments and introduce suitable chromophore-based reference materials. Moreover, the design concepts of the different BAM fluorescence standards are discussed.
T2 - COST 2017
CY - Turku, Finland
DA - 03.04.2017
KW - Fluorescence
KW - Dye
KW - Glass
KW - Calibration
KW - Fluorescence standard
KW - Integrating sphere spectroscopy
KW - Fluorescence quantum yield
KW - Instrument qualification
KW - Quality assurance
KW - NIR
KW - IR
PY - 2017
AN - OPUS4-43174
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Automated determination of genotoxicity of nanoparticles with DNA-based optical assays - The NANOGENOTOX project
N2 - The overall interest in nanotoxicity, triggered by the increasing use of nanomaterials in the material and life sciences, and the synthesis of an ever increasing number of new functional nanoparticles calls for standardized test procedures1,2 and for efficient approaches to screen the potential genotoxicity of these materials. Aiming at the development of fast and easy to use, automated microscopic methods for the determination of the genotoxicity of different types of nanoparticles, we assess the potential of the fluorometric γH2AX assay for this purpose. This assay, which can be run on an automated microscopic detection system, relies on the detection of DNA double strand breaks as a sign for genotoxicity3. Here, we provide first results obtained with broadly used nanomaterials like CdSe/CdS and InP/ZnS quantum dots as well as iron oxide, gold, and polymer particles of different surface chemistry with previously tested colloidal stability and different cell lines like Hep-2 and 8E11 cells, which reveal a dependence of the genotoxicity on the chemical composition as well as the surface chemistry of these nanomaterials. These studies will be also used to establish nanomaterials as positive and negative genotoxicity controls or standards for assay performance validation for users of this fluorometric genotoxicity assay. In the future, after proper validation, this microscopic platform technology will be expanded to other typical toxicity assays.
T2 - SPIE 2018
CY - San Francisco, USA
DA - 27.01.2018
KW - Nanoparticle
KW - Fluorescence
KW - Surface chemistry
KW - Size
KW - Assay
KW - Microscopy
KW - Nanotoxicity
KW - Toxicity
KW - Automation
KW - Calibration
KW - Standard
PY - 2018
AN - OPUS4-44186
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Geißler, Daniel
T1 - NanoGenotox - Automatable Determination of the Genotoxicity of Nanoparticles with DNA-based Optical Assays
N2 - Nanomaterials are used in many different applications in the material and life sciences. Examples are optical reporters, barcodes, and nanosensors, magnetic and optical contrast agents, and catalysts. Due to their small size and large surface area, there are also concerns about their interaction with and uptake by biological systems. This has initiated an ever increasing number of cyctoxicity studies of nanomaterials of different chemical composition and surface chemistry, but until now, the toxicological results presented by different research groups often do not address or differ regarding a potential genotoxicity of these nanomaterials. This underlines the need for a standardized test procedure to detect genotoxicity.1,2
Aiming at the development of fast, easy to use, and automatable microscopic methods for the determination of the genotoxicity of different types of nanoparticles, we assess the potential of the fluorometric γH2AX assay for this purpose. This assay, which can be run on an automated microscopic detection system, relies on the determination of DNA double strand breaks as a sign for genotoxicity.3 Here, we present first results obtained with broadly used nanomaterials like CdSe/CdS and InP/ZnS quantum dots as well as iron oxide, gold, and polymer particles of different surface chemistry with previously tested colloidal stability. These studies will be also used to establish nanomaterials as positive and negative genotoxicity controls or standards for assay performance validation for users of this fluorometric genotoxicity assay. In the future, after proper validation, this microscopic platform technology will be expanded to other typical toxicity assays.
References. (1) Landsiedel, R.; Kapp, M. D.; Schulz, M.; Wiench, K.; Oesch, F., Reviews in Mutation Research 2009, 681, 241-258. (2) Henriksen-Lacey, M.; Carregal-Romero, S.; Liz-Marzán, L. M., Bioconjugate Chem. 2016, 28, 212-221. (3) Willitzki, A.; Lorenz, S.; Hiemann, R.; Guttek, K.; Goihl, A.; Hartig, R.; Conrad, K.; Feist, E.; Sack, U.; Schierack, P., Cytometry Part A 2013, 83, 1017-1026.
T2 - 9th International Conference on Nanotoxicology - New tools in risk assessment of nanomaterials
CY - Dusseldorf/Neuss, Germany
DA - 18.09.2018
KW - Nano
KW - Nanotoxicity
KW - Fluorescence
KW - Quantum dot
KW - Surface
KW - Passivation shell
KW - Automated assay
KW - Nanoparticle
PY - 2018
AN - OPUS4-47540
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Scholtz, Lena
T1 - Luminescent polymer microbeads - Why and how?
N2 - Pitch Talk about the synthesis and applications of polymer microbeads encoded with (luminescent) nanoparticles.
T2 - JCF Frühjahrssymposium 2023
CY - Gießen, Germany
DA - 21.03.2023
KW - Fluorescence
KW - Microbeads
KW - Nanocrystals
KW - Polymerization
PY - 2023
AN - OPUS4-57260
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
ED - Martynenko, Irina
ED - Baimuratov, A. S.
ED - Osipova, V. A.
ED - Kuznetsova, V. A.
ED - Purcell-Milton, F.
ED - Rukhlenko, I. D.
ED - Fedorov, A. V.
ED - Gun'ko, Y. K.
ED - Baranov, A. V.
T1 - Excitation energy dependence of the photoluminescence quantum yield of core/shell CdSe/CdS quantum dots and correlation with circular dichroism
N2 - Quantum dot (QD) based nanomaterials are very promising materials for the fabrication of optoelectronic devices like solar cells, light emitting diodes (LEDs), and photodetectors as well as as reporters for chemo- and biosensing and bioimaging. Many of These applications involve the monitoring of changes in photoluminescence intensity and energy transfer processes which can strongly depend on excitation wavelength or energy. In this work, we analyzed the excitation energy dependence (EED) of the photoluminescence quantum yields (PL QYs) and decay kinetics and the circular dichroism (CD) spectra of CdSe/CdS core/shell QDs with different thicknesses of the surface passivation shell. Our results demonstrate a strong correlation between the spectral position of local maxima observed in the EED of PL QY and the zero-crossing points of the CD profiles. Theoretical analysis of the energy band structure of the QDs with effective mass approximation suggests that these structures could correspond to exciton energy levels. This underlines the potential of CD spectroscopy for the study of electronic energy structure of chiroptically active nanocrystals which reveal quantum confinement effects.
KW - Fluorescence
KW - Semiconductor
KW - Nanoparticle
KW - Surface chemistry
KW - Quantum yield
KW - Lifetime
KW - Nanocrystal
KW - Cysteine
KW - Thiol
KW - Ligand
KW - Quantum dot
KW - CdSe
KW - Exciton
KW - Circular dichroism
KW - Theory
KW - Excitation spectra
KW - Excitation energy dependence
PY - 2017
DO - https://doi.org/10.1021/acs.chemmater.7b04478
SN - 0897-4756
SN - 1520-5002
VL - 30
IS - 2
SP - 465
EP - 471
PB - ACS Publications
AN - OPUS4-44034
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Wegner, Karl David
T1 - SWIR luminescent nanomaterials – key chemical parameters for bright probes for in vivo bioimaging
N2 - A current challenge for studying physio-pathological phenomena and diseaserelated processes in living organisms with non-invasive optical bioimaging is the development of bright optical reporters that enable deep tissue penetration, a high detection sensitivity, and a high spatial and temporal resolution. The focus of this project are nanomaterials, which absorb and emit in the shortwave infrared (SWIR) between ~900–2500 nm where scattering, absorption, and autofluorescence of the tissue are strongly reduced compared to the visible and NIR.
T2 - QD2024 - 12th International Conference on Quantum Dots
CY - Munich, Germany
DA - 18.03.2024
KW - Quantum dots
KW - Advanced nanomaterials
KW - Fluorescence
KW - Quality assurance
KW - Gold nanocluster
KW - Shortwave infrared
KW - Spectroscopy
KW - Bioimaging
PY - 2024
AN - OPUS4-59783
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Effect of surface chemistry on optical, chemical and electronic properties of blue luminescent graphene quantum dots
N2 - Due to their unique physical properties, particularly their electronic and luminescent properties, graphene quantum dots (GQDs) are expected to be suitable for a wide range of applications in bioimaging, electro-optical and photonic materials or energy harvesting among others.1 Tuning the surface chemistry provides an efficient approach to modulate the fluorescence and distinct electronic properties of GQDs.2 Nevertheless, the role of surface chemistry on the electronic structure of GQDs remains poorly understood. In this presentation, we will compare systematically the electronic and chemical structures of GQDs functionalized with carboxylic and aminated groups to those of non-functionalized GQDs, combining theoretical and experimental approaches, here various photon-based spectroscopies. First, the electronic structure of GQDs was characterized by soft X-ray absorption (XA) and X-ray emission (XE) spectroscopies, probing unoccupied and occupied electronic states, respectively, at the carbon K edge for the first time. The interpretation of the XA/XE spectra was done based on theoretical calculations. Then, the chemical structure of the GQDs was characterized in situ by ATR-FTIR in water, thereby accounting for the importance of the interface between GQDs and water believed to play a central role in the chemical reactivity and the optical properties. We previously demonstrated that monitoring the OH vibrations of water molecules during exposure to humid air was a powerful method to probe H-bonding environment around carbon nanomaterials.3 For GQDs, clear surface-dependent water adsorption profiles are observed and discussed. Finally, UV/Vis absorption and photoluminescence measurements were done to characterize the optical properties of these GQDs. Our results suggest that the surface chemistry of the GQDs affects significantly their electronic structure and optical properties. These findings will contribute to an improved understanding of the structure–activity relationship of GQDs and other carbon nanomaterials with surface modifications.
T2 - MRS Fall Meeting 2017
CY - Boston, USA
DA - 26.11.2017
KW - Carbon
KW - Nanoparticle
KW - Fluorescence
KW - NIR
KW - IR
KW - Surface chemistry
KW - Deactivation pathways
KW - Lifetime
KW - Size
KW - Giant carbon dot
KW - Quantum yield
PY - 2017
AN - OPUS4-43494
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Applications and challenges of luminescence-based detection methods in the life and material sciences
N2 - Luminescence-based detection methods, ranging from fluorescence spectroscopy for photophysical and mechanistic studies over sensing applications, chromatographic separation techniques and the microarray technology with fluorescence detection to fluorescence microscopy, flow cytometry, single molecule spectroscopy, and molecular imaging to integrating sphere spectroscopy, are among the most widely used methods in the life and material sciences. This is due to e.g., their unique sensitivity enabling the detection of single molecules, potential for multiplexing, ease of combination with spatial resolution, and suitability for remote sensing. Many of these advantages are closely linked to the choice of suitable molecular and nanoscale fluorescent reporters, typically required for signal generation. This includes organic dyes without and with sensor function, fluorophore-encoded polymeric and silica nanoparticles as well as nanocrystalline systems like semiconductor quantum dots and upconversion phosphors, emitting in the visible (vis), near-infrared (NIR), and IR (infrared). Current challenges present the environment sensitivity of most fluorophores, rendering fluorescence spectra, measured intensities/fluorescence quantum yields, and fluorescence decay kinetics matrix-dependent, and instrument-specific distortions of measured fluorescence signals that need to be considered for quantification and comparability of data, particularly fluorescence spectra.
Here, current applications of luminescence-based methods and different types of reporters will be presented. In this context, suitable spectroscopic tools for the characteri-zation of the optical properties of fluorescent reporters and fluorophore-encoded microparticles, analytical tools for the determination of the surface chemistry of different types of particles, and different multiplexing strategies will be discussed.
T2 - 9th Meeting of Engineering of Functional Interfaces
CY - Wildau,Germany
DA - 03.07.2016
KW - Fluorescence
KW - Multiplexing
KW - Lifetime
KW - Nanomaterial
KW - Nanoparticle
KW - PEG
KW - Ligand
KW - Semiconductor quantum dot
KW - Quantum yield
KW - Quantification
KW - Upconversion nanoparticle
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence standard
KW - Calibration
PY - 2016
AN - OPUS4-37112
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Srivastava, Priyanka
T1 - Multi-color nanosensors for ratiometric measurements of acidic, neutral, and basic pH based on silica and polystyrene particles
N2 - pH presents one of the most important analytes in the life and material sciences, indicating, e.g., diseases and corrosion processes. This includes the optical monitoring of pH in living cells for studying cellular internalization pathways, such as phagocytosis, endocytosis, and receptor mediated internalization with the aid of molecular and nanoscale fluorescent sensors. Nanoparticle (NP)-based sensors, that are labelled or stained with a multitude of sensor dyes, have several advantages as compared to conventional molecular probes like enhanced brightness, i.e., amplified signals, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, this can enable the use of hydrophobic dyes in aqueous environments. Versatile templates and carriers for the fabrication of nanosensors by staining and/or labelling with different fluorophores and sensor molecules are surface-functionalized particles like silica (SiO2) and polystyrene (PS) particles. Here we present a platform of blue-red-green fluorescent pH nanosensors for the measurement of acidic, neutral, and basic pH utilizing both types of matrices and two spectrally distinguishable sensor dyes with an integrated reference dye and demonstrate its applicability for cellular studies.
T2 - E-MRS Spring Meeting 2022
CY - Online meeting
DA - 30.05.2022
KW - Nanosensors
KW - pH sensing
KW - Silica- and polystyrene particles
KW - Ratiometric sensors
KW - Fluorescence
PY - 2022
AN - OPUS4-55597
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schneider, Ralf
A1 - Weigert, Florian
A1 - Lesnyak, V.
A1 - Leubner, S.
A1 - Lorenz, T.
A1 - Behnke, Thomas
A1 - Dubavik, A.
A1 - Joswig, J.-O.
A1 - Resch-Genger, Ute
A1 - Gaponik, N.
A1 - Eychmüller, A.
ED - Resch-Genger, Ute
ED - Schneider, Ralf
T1 - pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O
N2 - The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms.
The latter is particularly important for CdTe NCs, which – together with alloyed CdₓHg₁₋ₓTe – are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA),
on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of the coordinative bond of the ligands to SC NC surface atoms, the influence of the pH (pD) and the concentration on the PL properties of these colloids was examined in water and D₂O and compared to the results from previous dilution studies with a set of thiol-capped Cd₁₋ₓHgₓTe SC NCs in D₂O. As a prerequisite for these studies, the number of surface ligands was determined photometrically at different steps of purification after SC NC synthesis with Ellman’s test.
Our results demonstrate ligand control of the pH-dependent PL of these SC NCs, with MPA-stabilized CdTe NCs being less prone to luminescence quenching than TGA-capped ones. For both types of CdTe colloids, ligand desorption is more pronounced in H₂O compared to D₂O, underlining also the role of hydrogen bonding and solvent molecules.
KW - Quantum dots
KW - Fluorescence
KW - Ligand analysis
KW - Nano particles
PY - 2016
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-371253
DO - https://doi.org/10.1039/c6cp03123d
VL - 18
IS - 28
SP - 19083
EP - 19092
PB - RSC
CY - Cambridge
AN - OPUS4-37125
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Gawlitza, Kornelia
A1 - Bartelmeß, Jürgen
A1 - Bartholmai, Matthias
A1 - Neumann, Patrick P.
A1 - Johann, Sergej
A1 - Tiebe, Carlo
T1 - Fluorescence sensor for the long-term monitoring of gaseous ammonia
N2 - Ammonia and its reaction products can cause considerable damage of human health and ecosystems, increasing the necessity for reliable and reversible sensors to monitor traces of gaseous ammonia in ambient air directly on-site or in the field. Although various types of gas sensors are available, fluorescence sensors have gained importance due to advantages such as high sensitivity and facile miniaturization.
Here, we present the development of a sensor material for the detection of gaseous ammonia in the lower ppm to ppb range by incorporation of a fluorescent dye, which shows reversible fluorescence modulations as a function of analyte concentration, into a polymer matrix to ensure the accumulation of ammonia. A gas standard generator producing standard gas mixtures, which comply with the metrological traceability in the desired environmentally relevant measurement range, was used to calibrate the optical sensor system. To integrate the sensor material into a mobile device, a prototype of a hand-held instrument was developed, enabling straightforward data acquisition over a long period.
T2 - Colloquium of Optical Spectrometry (COSP) 2017
CY - Berlin, Germany
DA - 27.11.2017
KW - Ammonia gas sensor
KW - Fluorescence
KW - Air quality monitoring
KW - Standard gas generator
KW - Miniaturized sensor device
PY - 2017
AN - OPUS4-43143
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Gawlitza, Kornelia
A1 - Tiebe, Carlo
A1 - Banach, Ulrich
A1 - Noske, Reinhard
A1 - Bartholmai, Matthias
A1 - Rurack, Knut
T1 - Novel sensor for long-term monitoring of ammonia in gas phase
N2 - Because ammonia and its reaction products can cause considerable damage to human health and ecosystems, there is a need for reliably operating and reversibly interacting sensor materials to monitor traces of gaseous ammonia in ambient air, which at best can be used on-site for in-the-field measurements. Herein, the development of a sensor material for gaseous ammonia in the lower ppm to ppb range using optical fluorescence as transduction mechanism is presented. A fluorescent dye, which shows reversible fluorescence enhancement in the presence of ammonia is incorporated into a polymer matrix, the latter to ensure the accumulation of ammonia. The sensor material is integrated into a prototype of a miniaturized sensor device, facilitating long-term operation. To calibrate the optical sensor system a gas standard generator, producing standard gas mixtures, is used, leading to a sensitivity down to lower ppm concentrations of ammonia.
T2 - 13. Dresdner Sensor-Symposium 2017
CY - Dresden, Germany
DA - 04.12.2017
KW - Ammonia gas sensor
KW - Fluorescence
KW - Air quality monitoring
KW - Standard gas generator
KW - Miniaturized sensor device
PY - 2017
DO - https://doi.org/10.5162/13dss2017/P4.02
SP - P4.02, 272
EP - 276
AN - OPUS4-43352
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Sun, Yijuan
A1 - Pérez-Padilla, Víctor
A1 - Valderrey, Virginia
A1 - Bell, Jérémy
A1 - Gawlitza, Kornelia
A1 - Rurack, Knut
T1 - Ratiometric detection of perfluoroalkyl carboxylic acids using dual fluorescent nanoparticles and a miniaturised microfluidic platform
N2 - The widespread contamination of soil and water with perfluoroalkyl substances (PFAS) has caused considerable societal and scientific concern. Legislative measures and an increased need for remediation require effective on-site analytical methods for PFAS management. Here we report on the development of a green-fluorescent guanidine-BODIPY indicator monomer incorporated into a molecularly imprinted polymer (MIP) for the selective detection of perfluorooctanoic acid (PFOA). Complexation of PFOA by the indicator, which is mediated by concerted protonation-induced ion pairing-assisted hydrogen bonding, significantly enhances fluorescence in polar organic solvents. The MIP forms as a thin layer on silica nanoparticles doped with tris(bipyridine)ruthenium(II) chloride, which provides an orange emission signal as internal reference, resulting in low measurement uncertainties. Using a liquid-liquid extraction protocol, this assay enables the direct detection of PFOA in environmental water samples and achieves a detection limit of 0.11 µM. Integration into an opto-microfluidic system enables a compact and user-friendly system for detecting PFOA in less than 15 minutes.
KW - PFAS
KW - Molecular imprinting
KW - Microfluidics
KW - Fluorescence
KW - Onsite assay
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650270
DO - https://doi.org/10.1038/s41467-025-66872-9
SN - 2041-1723
VL - 16
IS - 1
SP - 1
EP - 16
PB - Springer Science and Business Media LLC
AN - OPUS4-65027
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Oskoei, Párástu
A1 - Afonso, Rúben
A1 - Bastos, Verónica
A1 - Nogueira, João
A1 - Keller, Lisa-Marie
A1 - Andresen, Elina
A1 - Saleh, Maysoon I.
A1 - Rühle, Bastian
A1 - Resch-Genger, Ute
A1 - Daniel-da-Silva, Ana L.
A1 - Oliveira, Helena
T1 - Upconversion Nanoparticles with Mesoporous Silica Coatings for Doxorubicin Targeted Delivery to Melanoma Cells
N2 - Melanoma is one of the most aggressive skin cancers and requires innovative therapeutic strategies to overcome the limitations of conventional therapies. In this work, upconversion nanoparticles coated with mesoporous silica and functionalized with folic acid (UCNP@mSiO2-FA) were developed as a targeted nanocarrier system for the delivery of doxorubicin (DOX). The UCNPs were synthesized via thermal decomposition, coated with mesoporous silica shells, and functionalized with folic acid (FA) to enable receptor-mediated targeting. DOX was then loaded into the mesoporous silica coating by adsorption, yielding UCNP@mSiO2-FA-DOX. The different UCNPs were characterized for size, composition, colloidal stability, and loading and release of DOX. This comprehensive physicochemical characterization confirmed a high DOX loading efficiency and a slightly increased drug release under acidic conditions, mimicking the tumour microenvironment. In vitro assays using four melanoma cell lines (A375, B16-F10, MNT-1, and SK-MEL-28) revealed an excellent biocompatibility of UCNP@mSiO2-FA and a significantly higher cytotoxicity of UCNP@mSiO2-FA-DOX compared to unloaded UCNPs, in a dose-dependent manner. Cell cycle analysis demonstrated G2/M phase arrest after treatment with UCNP@mSiO2-FA-DOX, confirming its antiproliferative effect. Overall, UCNP@mSiO2-FA-DOX represents a promising nanoplatform for targeted melanoma therapy, combining active tumour targeting and enhanced anticancer efficacy.
KW - Fluorescence
KW - Synthesis
KW - Nano
KW - Particle
KW - Silica
KW - Cell
KW - Uptake
KW - Drug
KW - Characterization
KW - DOX
KW - Imaging
KW - Toxicity
KW - Release
KW - pH
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653596
DO - https://doi.org/10.3390/molecules31010074
SN - 1420-3049
VL - 31
IS - 1
SP - 1
EP - 18
PB - MDPI AG
AN - OPUS4-65359
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Rodriguez, Santiago
A1 - Kumanski, Sylvain
A1 - Ayed, Zeineb
A1 - Fournet, Aurélie
A1 - Bouanchaud, Charlène
A1 - Sagar, Amin
A1 - Allemand, Frédéric
A1 - Baulin, Vladimir A.
A1 - Resch‐Genger, Ute
A1 - Cortés, Juan
A1 - Sibille, Nathalie
A1 - Chirot, Fabien
A1 - Wegner, Karl David
A1 - Antoine, Rodolphe
A1 - Le Guével, Xavier
A1 - Bernadó, Pau
T1 - Programming the Optoelectronic Properties of Atomically Precise Gold Nanoclusters Using the Conformational Landscape of Intrinsically Disordered Proteins
N2 - The rational design of hybrid nanomaterials with precisely controlled properties remains a central challenge in materials science. While atomically precise gold nanoclusters (Au‐NCs) offer molecule‐like control over a metallic core, tuning their optoelectronic behavior via surface engineering is often empirically driven. Here, we establish a design principle by demonstrating that the conformational landscape of intrinsically disordered proteins (IDP) can be used as a programmable scaffold to rationally modulate the photophysical properties of a covalently bound Au‐NC. We synthesized a series of bioconjugates between Au 25 nanoclusters and bioengineered IDPs containing a variable number of cysteine anchoring points. A combination of mass spectrometry, small‐angle X‐ray scattering, and modeling on the conjugates indicates that increasing the number of covalent anchors systematically restricts the conformational ensemble, inducing a progressively more compact protein shell around nanoclusters. This structural rigidification at the interface directly translates into a 15‐fold enhancement of the Au‐NC near‐infrared photoluminescence and a six‐fold increase in its average lifetime. Our findings demonstrate that the conformational plasticity of IDPs and the capacity to engineer them can be harnessed as a molecular tuning knob, moving to a new regime of programmable soft‐matter control over the properties of quantum‐confined nanomaterials for tailored biotechnological applications.
KW - Fluorescence
KW - Custer
KW - Nano
KW - Advanced material
KW - Characterization
KW - Fluorescence quantum yield
KW - Integrating sphere spectroscopy
KW - Thiol ligands
KW - Gold
KW - Surface chemistry
KW - SWIR
KW - Mass spectrometry
KW - Protein
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655086
DO - https://doi.org/10.1002/chem.202502991
SN - 0947-6539
SP - 1
EP - 9
PB - Wiley VHC-Verlag
AN - OPUS4-65508
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Rurack, Knut
T1 - Advanced Onsite Analysis for Point-of-Need Applications: Innovations for Robust, Reliable, and User-Friendly Detection
N2 - The advancement of portable analytical assays has transformed onsite analysis in several areas, including food safety, environmental monitoring and forensics. The SARS-CoV-2 pandemic has fueled a need for rapid, onsite solutions that enable immediate decision making without the need for and use of laboratory infrastructure. The integration of mobile devices with advanced cameras and significant computing power improves the accessibility and usability of these tests. However, many current methods are limited to the detection of single parameters. The next challenge is to develop robust multiplexed assays that can analyze multiple parameters simultaneously with high sensitivity. In this lecture, innovative approaches developed at BAM will be presented with a focus on supramolecular chemistry, luminescence detection, nanomaterials and miniaturization of devices. Examples will include mesoporous nanomaterials, gated indicator systems, imprinted polymers, microfluidic devices, test strips and smartphone-based analytical tools, focusing on two use cases, i.e., the detection of contaminants in surface waters and immunoanalytical explosives detection.
T2 - International Conference on Emergin Trends in Materials Chemistry
CY - Coimbatore, India
DA - 03.04.2025
KW - Onsite analysis
KW - Rapid tests
KW - Mobile devices
KW - Supramolecular chemistry
KW - Fluorescence
PY - 2025
AN - OPUS4-65434
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Ramirez Caro, Alejandra
A1 - Pauli, Jutta
A1 - Schmidt, Wolfram
A1 - Resch-Genger, Ute
T1 - Study of the superplasticizer-cement hydration interaction by optical spectroscopy
N2 - Nowadays, superplasticizers (SPs) are widely used to increase fluidity and reduce water content in concrete; thus, allowing better workability for final applications. The present study will focus on the hydration effect using comb shape polycarboxylates (PCEs), which are known to allow a very low water/cement ratio (w/c of 0.20) or less.Optical methods have been successfully used for the analysis and monitoring of the interactions between a broad variety of nanoscale and molecular systems like nanoparticles of various chemical composition and different types of organic ligands or biomolecules.This encouraged us to assess the potential of these methods, and particularly fluorescence, for the investigation of the interactions that occur at the interface between hydrate surfaces of cement particles and PCE at a very early stage of concrete formation and to differentiate between the impact of PCE’s molecular structures on such interactions.
T2 - 2nd International Conference on the Chemistry of Construction Materials
CY - Munich, Germany
DA - 10.10.2016
KW - Cement
KW - Dye
KW - Superplasticizers
KW - Fluorescence
PY - 2016
SN - 978-3-936028-96-6
VL - 50
SP - 260
EP - 263
PB - Gesellschaft Deutscher Chemiker e.V.
CY - Frankfurth am Main
AN - OPUS4-38881
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ramirez Caro, Alejandra
A1 - Pauli, Jutta
A1 - Mota, Berta
A1 - Simon, Sebastian
A1 - Schmidt, Wolfram
A1 - Resch-Genger, Ute
T1 - C3A passivation with gypsum and hemihydrate monitored by optical spectroscopy
N2 - Tricalcium aluminate (C3A) is found with less than 10% wt. of the total composition; however, during hydration, C3A plays an important role in the early hydration of cement in the presence of gypsum as a set retarder.
The aim of this investigation is to assess the suitability of optical spectroscopy and a dye-based optical probe to monitor early hydration of C3A in the presence of gypsum and hemihydrate. Optical evaluation was performed using steady-state fluorescence and diffuses reflectance spectroscopy (UV-VisDR). Phase characterization during hydration was done with in-situ X-ray diffraction. UV-VisDR with a cyanine dye probe was used to monitor the formation of metastable phases and was employed together with fluorescence spectroscopy, to follow the Aggregation and disaggregation of the dye during hydration. In conclusion, for the first time, a cyanine dye was identified as a feasible and stable probe to monitor C3A hydration changes in the presence of calcium sulfate.
KW - Dye
KW - Photoluminescence
KW - Fluorescence
KW - Reflection spectroscopy
KW - Cement
KW - Hydration
KW - Method development
PY - 2020
DO - https://doi.org/10.1016/j.cemconres.2020.106082
VL - 133
SP - 106082
PB - Elsevier Ltd.
CY - Amsterdam
AN - OPUS4-50952
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Scholtz, Lena
T1 - Luminescent, Semiconductor Nanoparticle-Loadedpolymer Microbeads–Comparingparticlearchitectures
N2 - Luminescent polymer microparticles (PMPs) are applied in various (bio)analytical and diagnostic processes.[1] The staining of these beads is important for the realization of optically distinguishable barcodes that can be read out, e.g., by a flow cytometer or fluorescence microscope. Typically, luminescent semiconductor nanoparticles (NPs) absorb in a broad wavelength range and show narrow emission bands, which enables simultaneous excitation of differently colored luminophores and facilitates a spectral discrimination.[1] This makes them ideal candidates for this purpose and encouraged us to explore and develop a simple, effective approach to luminescent semiconductor NP encoding of polystyrene PMPs and identify suitable synthesis conditions.[2]
Until now, mainly semiconductor quantum dots (QDs) have been used for the synthesis of luminescent PMPs, although NPs with different shapes could introduce beneficial new features. Aiming for the application of our developed procedure to non-spherical NPs, we systematically investigated the luminescence properties of the resulting NP-stained beads using fluorescence and integrating sphere spectroscopy as well as fluorescence and electron microscopy. These studies showed that the suitability of semiconductor NPs for the synthesis of luminescent PMPs depends not only on their shape, but also heavily on their surface chemistry.[3] The successful incorporation of nonspherical NPs opens the path to include even more NPs, and the results can help to deduce future applications for the beads which best suit their specific properties.
T2 - E-MRS Fall Meeting 2025
CY - Warsaw, Poland
DA - 15.09.2025
KW - Quality assurance
KW - Fluorescence
KW - Nano
KW - Particle
KW - Synthesis
KW - Quantum dot
KW - Quantum rod
KW - Platelet
KW - Quantum yield
KW - Polymer particle
KW - Encoding
KW - Surface chemistry
KW - Mechanism
KW - Characterization
KW - Lifetime
KW - Barcode
KW - Polymerization
KW - Method
PY - 2025
AN - OPUS4-64242
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Andresen, Elina
A1 - Resch-Genger, Ute
A1 - Michaelis, Matthias
A1 - Prinz, Carsten
A1 - Würth, Christian
T1 - Time-resolved luminescence spectroscopy for monitoring the stability and dissolution behaviour of upconverting nanocrystals with different surface coatings†
N2 - We demonstrate the potential of time-resolved luminescence spectroscopy for the straightforward assessment and in situ monitoring of the stability of upconversion nanocrystals (UCNPs). Therefore, we prepared hexagonal NaYF4:Yb3+,Er3+ UCNPs with various coatings with a focus on phosphonate ligands of different valency, using different ligand exchange procedures, and studied their dissolution behaviour in phosphate-buffered saline (PBS) dispersions at 20 °C and 37 °C with various analytical methods. The amount of the released UCNPs constituting fluoride ions was quantified by potentiometry using a Fluoride ion-sensitive electrode and particle disintegration was confirmed by transmission electron microscopy studies of the differently aged UCNPs. In parallel, the luminescence features of the UCNPs were measured with special emphasis on the lifetime of the sensitizer emission to demonstrate its suitability as Screening parameter for UCNP stability and changes in particle composition. The excellent correlation between the changes in luminescence lifetime and fluoride concentration highlights the potential of our luminescence lifetime method for UCNP stability screening and thereby indirect monitoring of the release of potentially hazardous fluoride ions during uptake and dissolution in biological systems. Additionally, the developed in situ optical method was used to distinguish the dissolution dynamics of differently sized and differently coated UCNPs.
KW - Fluorescence
KW - Lifetime
KW - Method
KW - Quantification
KW - Stability
KW - Coating
KW - Surface chemistry
KW - Lanthanide
KW - Fluoride
KW - Electrochemistry
KW - ICP-OES
KW - Upconversion
KW - Nano
KW - Particle
KW - Aging
KW - Quality assurance
KW - TEM
PY - 2020
DO - https://doi.org/10.1039/d0nr02931a
VL - 12
IS - 23
SP - 12589
EP - 12601
PB - Royal Society od Chemistry
AN - OPUS4-52088
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Prakash, Swayam
A1 - Bell, Jérémy
A1 - Rurack, Knut
T1 - Rapid Onsite Detection of Fecal Contamination in Water Using a Portable Fluorometric Assay
N2 - Fecal pollution in water poses significant health risks, especially when contaminated sources are used for drinking and food production. Traditional water quality testing methods are expensive, slow, and require skilled personnel, limiting their accessibility. This work addresses these issues by developing a portable fluorometric assay for the detection of the fecal indicator pigment urobilin (UB). The assay uses silane-functionalized glass fiber strips impregnated with zinc chloride, providing a ‘drop-&-detect’ approach with enhanced fluorescence response mediated by the unique complexation properties of ZnCl2 and UB. This approach allows for the detection of UB at sub-nanomolar concentrations in less than 1 min using a 3D-printed setup with miniaturized optical components powered by a smartphone with its camera as a detector. The results validated with a benchtop fluorometer show the effectiveness of this method. The successful application of this userfriendly, rapid, and sensitive assay to real water samples from three rivers and the influx and efflux of a wastewater treatment plant advances field-based water quality monitoring, meets the WHO’s ASSURED criteria, and supports progress toward the global clean water and sanitation goals.
KW - Fecal pigment
KW - Fluorescence
KW - Signal amplification
KW - Surface chemistry
KW - Water quality testing
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655543
DO - https://doi.org/10.1021/acssensors.5c03922
SN - 2379-3694
VL - 11
SP - 1
EP - 9
PB - American Chemical Society
CY - Washington, D.C.
AN - OPUS4-65554
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - How to get it right with photoluminescence measurements in the UV/VIS/NIR
N2 - Optical measurements of transparent solutions of organic dyes and semiconductor quantum dots and scattering materials such as luminescent nanocomposites and microparticles and phosphors dispersed in liquid and solid matrices play an important role in energy conversion, solid-state lighting, medical diagnostics, and security barcoding. A key performance parameter is the photoluminescence quantum yield QY, i.e., the number of emitted per number of absorbed photons. QY of transparent luminophore solutions can be obtained relative to a fluorescence QY standard of known QY. Such relative QY measurements require a calibrated spectrofluorometer. Here, we address typical sources of uncertainty for luminescence measurements and relative and absolute QY measurements from the instrument and material side and provide recommendations to circumvent or at least minimize them for transparent and scattering samples in the UV/vis/NIR/SWIR.
T2 - Workshop "Photoluminescence Spectroscopy and its application in Materials Research"
CY - Vienna, Austria
DA - 19.02.2026
KW - Quality assurance
KW - Reference material
KW - Fluorescence
KW - Dye
KW - Traceability
KW - Metrology
KW - Calibration
KW - Reference data
KW - Reference product
KW - Digital certificate
KW - NIR
KW - Instrument performance validation
PY - 2026
AN - OPUS4-65575
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Influence of Surface Chemistry and Size on the Stability of β-NaYF4:Yb,Er Nanocrystals in Various Environments
N2 - The use of inorganic lanthanide-doped upconversion nanoparticles (UCNP) in bioimaging and cellular studies requires biocompatible particles. One possible cause of UCNP toxicity is the release of potentially harmful fluoride and lanthanide ions as revealed by dilution studies in aqueous environments, particularly under high dilution conditions. To address this issue, suitable surface coatings preventing such effects in combination with fast screening methods suited for online monitoring and in situ analyses are desired.
Here we present systematic studies of differently sized β-NaYF4:Yb,Er UCNP stabilized with different surface coatings and hydrophilic ligands varying in binding strength to the particle surface in various aqueous environments at different temperatures and UCNP concentrations. The concentration of the fluoride and lanthanide ions released upon particle dissolution was quantified electrochemically with a fluoride ion-sensitive electrode and inductively coupled plasma optical emission spectrometry (ICP-OES) and monitored fluorometrically, thereby exploiting the sensitivity of the upconversion luminescence to changes in size and surface chemistry. Moreover, changes in surface chemistry were determined with X-Ray photoelectron spectroscopy (XPS). Based upon our results, we could derive optimum screening parameters for UCNP stability studies and determine conditions and coating procedures and ligands for enhancing UCNP stability in aqueous environments.
T2 - UPCON2021
CY - Online meeting
DA - 06.04.2021
KW - Fluorescence
KW - Lifetime
KW - Method
KW - Quantification
KW - Stability
KW - Coating
KW - Surface chemistry
KW - Lanthanide
KW - Fluoride
KW - Electrochemistry
KW - ICP-OES
KW - Upconversion
KW - Nano
KW - Particle
KW - Aging
KW - Quality assurance
KW - Mass spectrometry
KW - XPS
PY - 2021
AN - OPUS4-52411
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kossatz, Philipp
A1 - Mezhov, Alexander
A1 - Andresen, Elina
A1 - Prinz, Carsten
A1 - Schmidt, Wolfram
A1 - Resch-Genger, Ute
T1 - Assessing the Applicability of Lanthanide-Based Upconverting Nanoparticles for Optically Monitoring Cement Hydration and Tagging Building Materials
N2 - Chemically stable, lanthanide-based photon upconversion micro- and nanoparticles (UCNPs) with their characteristic multicolor emission bands in the ultraviolet (UV), visible (vis), near-infrared (NIR), and short-wave infrared (SWIR) arepromising optical reporters and barcoding tags. To assess the applicability of UCNPs for the monitoring of early stage cement hydration processes and as authentication tags for cementitious materials, we screened the evolution of the luminescence of Selfmade core-only NaYF4:Yb,Er UCNPs and commercial μm-sized Y2O2S:Yb,Er particles during the first stages of cement hydration, which largely determines the future properties of the hardened material. Parameters explored from the UCNP side included particle size, morphology, surface chemistry or coating, luminescence properties, and concentration in different cement mixtures. From the cement side, the influence of the mineral composition of the cement matrix was representatively examined for ordinary Portland cement (OPC) and its constituents tricalcium aluminate (C3A), tricalcium silicate (C3S), and gypsum at different water to cement ratios. Based on reflection and luminescence measurements, enabling online monitoring, which were complemented by XRD and isothermal heat-flow calorimetric measurements to determine whether the incorporation of these particles could impair cement hydration processes, well suited lanthanide particle reporters could be identified as well as application conditions. In addition, thereby the reporter influence on cement hydration kinetics could be minimized while still preserving a high level of information content. The best performance for the luminescence probing of changes during early stage cement hydration processes was observed for 25 nm-sized oleate (OA)-coated UCNPs added in a concentration of 0.1 wt %. Higher UCNP amounts of 1.0 wt % delayed cement hydration processes size- and surface coatingspecifically in the first 24 h. Subsequent luminescence stability screening studies performed over a period of about one year support the applicability of UCNPs as optical authentication tags for construction materials.
KW - Quality assurance
KW - Fluorescence
KW - Nano
KW - Particle
KW - Synthesis
KW - Quantum yield
KW - NIR
KW - Mechanism
KW - Characterization
KW - XRD
KW - Calorimetry
KW - Advanced material
KW - Cement
KW - Monitoring
KW - Surface
KW - Size
KW - Lifetime
KW - Barcode
KW - Lanthanide
KW - Upconversion
KW - Encoding
KW - Method
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638318
DO - https://doi.org/10.1021/acsomega.5c02236
SN - 2470-1343
VL - 10
IS - 29
SP - 31587
EP - 31599
PB - ACS Publications
CY - Washington, DC
AN - OPUS4-63831
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Johann, Sergej
T1 - Semi-automatic Gas Measurement Device Based on Fluorescent Multi-gas Sensors
N2 - This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables.
T2 - IEEE Sensors 2019
CY - Montreal, Canada
DA - 27.10.2019
KW - Gas analysis
KW - Fluorescence
KW - Embedded sensor
KW - Spectroscopy
KW - Environment
KW - Agricultural economy
PY - 2019
AN - OPUS4-49502
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Wang, Cui
T1 - Ratiometric Nanosensors for Simultaneously “TOP” Measuring Temperature, Oxygen and pH at a Single Excitation Wavelength
N2 - In summary, by combining the NIR-emissive [Cr(ddpd)2][BPh4]3 complex CrBPh4 with its extremely large energy gap between the longest wavelength absorption and emission maxima with a pH-responsive fluorescein derivative (FITC) and an inert reference dye like Nile Red (NR) and 5,10,15,20tetrakis(pentafluorophenyl) porphyrin (TFPP), we developed nanosensors for simultaneously sensing temperature, O2 partial pressure, and pH. These novel TOP nanosensors (temperature, oxygen, pH) cover the biologically and physiologically relevant concentration ranges of these parameters/analytes with single wavelength excitation in PBS buffer and in a cell culture medium containing bovine serum albumin (BSA). The response of both nanosensors to all parameters is fully reversible and only minimally affected by the presence of BSA, the most common serum albumin. Moreover, comparative studies with nanosensors containing only a single type of stimuli-responsive molecule and with the respective molecular systems revealed that the different sensor components do not interfere with each other. Future research will include the testing of these nanosensors in cellular uptake studies and, after surface modification with targeted bioligands, eventually in in vivo experiments as previously done by some of us with other polystyrene nanoparticle reporters and nanosensors.46,47 Moreover, this concept of multianalyte sensing will be expanded to nanosensors derived from differently sized premanufactured biocompatible polymer particles and different stimuli-responsive dyes like fluorescent indicators for biologically and bioanalytically relevant metal ions.
T2 - ISPPCC 2019
CY - Hong Kong, China
DA - 14.07.2019
KW - Medical diagnostics
KW - Sensor
KW - Nnanoparticle
KW - Nanosensor
KW - Fluorescence
KW - Oxygen
KW - Temperature
KW - Ratiometric
KW - PH
KW - Lifetime
KW - NIR
KW - Cr(III) complex
KW - FITC
KW - Dye
KW - Environment
PY - 2019
AN - OPUS4-49698
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Heck, C.
A1 - Michaeli, Y.
A1 - Bald, Ilko
A1 - Ebenstein, Y.
T1 - Analytical epigenetics: single-molecule optical detection of DNA and histone modifications
N2 - The field of epigenetics describes the relationship between genotype and phenotype, by regulating gene expression without changing the canonical base sequence of DNA. It deals with molecular genomic information that is encoded by a rich repertoire of chemical modifications and molecular interactions. This regulation involves DNA, RNA and proteins that are enzymatically tagged with small molecular groups that alter their physical and chemical properties. It is now clear that epigenetic alterations are involved in development and disease, and thus, are the focus of intensive research. The ability to record epigenetic changes and quantify them in rare medical samples is critical for next generation diagnostics. Optical detection offers the ultimate single-molecule sensitivity and the potential for spectral multiplexing. Here we review recent progress in ultrasensitive optical detection of DNA and histone modifications.
KW - Epigenetics
KW - Fluorescence
KW - SERS
PY - 2019
UR - https://www.sciencedirect.com/science/article/pii/S095816691830082X
DO - https://doi.org/10.1016/j.copbio.2018.09.006
SN - 0958-1669
VL - 55
SP - 151
EP - 158
PB - Elsevier
AN - OPUS4-46680
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Descalzo, Ana B.
A1 - Ashokkumar, Pichandi
A1 - Shen, Z.
A1 - Rurack, Knut
T1 - On the Aggregation Behaviour and Spectroscopic Properties of Alkylated and Annelated BoronDipyrromethene (BODIPY) Dyes in Aqueous Solution
N2 - The tendency of boron-dipyrromethene (BODIPY) dyes to associate in water is well known, and usually a cause for inferior fluorescence properties. Synthetic efforts to chemically improve BODIPYs’ water solubility and minimize this problem have been numerous in the past. However, a deeper understanding of the phenomena responsible for fluorescence quenching is still required. Commonly, the spectroscopic behaviour in aqueous media has been attributed to aggregate or excimer formation, with such works often centring on a single BODIPY family. Herein, we provide an integrating discussion including very diverse types of BODIPY dyes. Our studies revealed that even subtle structural changes can distinctly affect the association behaviour of the fluorophores in water, involving different photophysical processes. The palette of behaviour found ranges from unperturbed emission, to the formation of H or J aggregates and excimers, to the involvement of tightly bound, preformed excimers. These results are a first step to a more generalized understanding of spectroscopic properties vs. structure, facilitating future molecular design of BODIPYs, especially as probes for biological applications.
KW - Aggregates
KW - BODIPY
KW - Excimers
KW - Fluorescence
KW - Photophysics
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-497771
DO - https://doi.org/10.1002/cptc.201900235
SN - 2367-0932
VL - 4
IS - 2
SP - 120
EP - 131
PB - WILEY-VCH
CY - Weinheim
AN - OPUS4-49777
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Liu, H.
A1 - Song, W.
A1 - Gröninger, Delia
A1 - Zhang, L.
A1 - Lu, Y.
A1 - Chan, K. S.
A1 - Zhou, Z.
A1 - Rurack, Knut
A1 - Shen, Z.
T1 - Real-time monitoring of newly acidified organelles during autophagy enabled by reaction-based BODIPY dyes
N2 - Real-time monitoring of newly acidified organelles during autophagy in living cells is highly desirable for a better understanding of intracellular degradative processes. Herein, we describe a reaction-based boron dipyrromethene (BODIPY) dye containing strongly electron-withdrawing diethyl 2-cyanoacrylate groups at the α-positions. The probe exhibits intense red fluorescence in acidic organelles or the acidified cytosol while negligible fluorescence in other regions of the cell. The underlying mechanism is a nucleophilic reaction at the central meso-carbon of the indacene core, resulting in the loss of π-conjugation entailed by dramatic spectroscopic changes of more than 200 nm between its colorless, non-fluorescent leuco-BODIPY form and its red and brightly emitting form. The reversible transformation between red fluorescent BODIPY and leuco-BODIPY along with negligible cytotoxicity qualifies such dyes for rapid and direct intracellular lysosome imaging and cytosolic acidosis detection simultaneously without any washing step, enabling the real-time monitoring of newly acidified organelles during autophagy.
KW - Autophagy
KW - BODIPY
KW - Fluorescence
KW - Lysosome
KW - Real-time imaging
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-498358
UR - https://www.nature.com/articles/s42003-019-0682-1
DO - https://doi.org/10.1038/s42003-019-0682-1
SN - 23993642
VL - 2
SP - 442
PB - Nature Research
CY - London
AN - OPUS4-49835
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Photoluminescence Properties of Different Types of Nanocrystals at the Ensemble and Single Emitter Level
N2 - Correlating the photoluminescence (PL) properties of nanomaterials like semiconductor nanocrystals (QDs) and upconversion nanocrystals (UCNPs) assessed in ensemble studies and at the single particle level is increasingly relevant for applications of these nanomaterials in the life sciences like bioimaging studies or their use as reporters in microfluidic assays. Here we present a comparison of the spectroscopic properties of ensembles and single emitters for QDs like II/VI QDs and cadmium-free AIS/ZnS QDs as well as different UCNPs. The overall goal of this study was to derive particle architectures well suited for spectroscopic and microscopic applications.
T2 - BIOSSPIE
CY - San Francisco, CA, USA
DA - 02.02.2019
KW - Quantum yield
KW - Nanomaterial
KW - Photoluminescence
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy,
KW - NIR
KW - IR
KW - Fluorescence
KW - Nanoparticle
KW - Semiconductor
KW - Quantum dot
KW - Single particle spectroscopy
KW - Surface chemistry
PY - 2019
AN - OPUS4-47358
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Relative and Absolute Methods for Measuring Photoluminescence Quantum Yields of UV/vis/NIR Emitters
N2 - One of the key spectroscopic performance parameters of molecular and particulate emitters is the photoluminescence quantum yield (PL QY) that provides a direct measure for the number of emitted per absorbed photons. This triggered the interest in methods suitable for measuring this property for emitters in various environments in the UV/vis/NIR and above 1000 nm as well as on the ensemble and single emitter level. Moreover, for nonlinear emitters like lanthanide-based upconversion nanocrystals methods including instrumentation for power density-dependent PL QY studies are required.
An overview of the research activities in Division Biophotonics of BAM is given and suitable relative and absolute methods for the deter-mination of PL QY of organic dyes and different types of application-relevant nanomaterials in dispersion and in the solid state are presen-ted. This covers also the design and calibration of integrating sphere setups, achievable uncertainties, and candidates for PL QY reference materials.
T2 - OSRAM Veranstaltung
CY - Regensburg, Germany
DA - 09.01.2019
KW - Quantum yield
KW - Calibration
KW - Reference material
KW - Uncertainty
KW - Absolute fluorometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Fluorescence
KW - Nanoparticle
KW - Dye
PY - 2019
AN - OPUS4-47263
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Martynenko, Irina V.
A1 - Kusic, Dragana
A1 - Weigert, Florian
A1 - Stafford, S.
A1 - Donnelly, F. C.
A1 - Evstigneev, R.
A1 - Gromova, Y.
A1 - Baranov, A. V.
A1 - Rühl, Bastian
A1 - Kunte, Hans-Jörg
A1 - Gun'ko, Y. K.
A1 - Resch-Genger, Ute
T1 - Magneto-fluorescent microbeads for bacteria detection constructed from superparamagnetic Fe3O4 nanoparticles and AIS/ZnS quantum dots
N2 - The efficient and sensitive detection of pathogenic microorganisms in aqueous environments, such as water used in medical applications, drinking water, and cooling water of industrial plants, requires simple and fast methods suitable for multiplexed detection such as flow cytometry (FCM) with optically encoded carrier beads. For this purpose, we combine fluorescent Cd-free Ag−In−S ternary quantum dots (t-QDs) with fluorescence Lifetimes (LTs) of several hundred nanoseconds and superparamagnetic Fe3O4 nanoparticles (SPIONs) with mesoporous CaCO3 microbeads to a magneto-fluorescent bead platform that can be surface-functionalized with bioligands, such as antibodies. This inorganic bead platform enables immuno-magnetic separation, target enrichment, and target quantification with optical readout. The beads can be detected with steady-state and time-resolved fluorescence microscopy and flow cytometry (FCM). Moreover, they are suited for readout by time gated emission. In the following, the preparation of these magneto-fluorescent CaCO3 beads, their spectroscopic and analytic characterization, and their conjugation with bacteria-specific antibodies are presented as well as proof-of-concept measurements with Legionella pneumophila including cell cultivation and plating experiments for bacteria quantification. Additionally, the possibility to discriminate between the long-lived emission of the LT-encoded capture and carrier CaCO3 beads and the short-lived Emission of the dye-stained bacteria with time-resolved fluorescence techniques and single wavelength excitation is demonstrated.
KW - Fluorescence
KW - method
KW - lifetime
KW - quantum yield
KW - particle
KW - magnetic nanoparticle
KW - immunoseparation
KW - flow cytometry
KW - fluorescence microscopy
KW - nanoparticle
KW - quantum dot
KW - AIS QD
KW - fluorescence
KW - bacteria detection
KW - bacteria
KW - antibody
KW - Legionella
KW - screening tes
KW - FLIM
PY - 2019
DO - https://doi.org/10.1021/acs.analchem.9b01812
SN - 0003-2700
SN - 1520-6882
VL - 91
SP - 12661
EP - 12669
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-50117
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Pauli, Jutta
T1 - Determination of the Uncertainty Budgets of the Fluorescence Quantum Yield Values of Certified Standards as New Optical Reference Materials
N2 - Luminescence techniques are amongst the most commonly used analytical methods in the life and material sciences due to their high sensitivity and their nondestructive and multiparametric character. Photoluminescence signals are, however, affected by wavelength-, polarization- and time-dependent instrument specific effects. This hampers the comparability of fluorescence measurements and calls for simple tools for instrument characterization and the quantification of measured fluorescence intensities. Well characterized fluorescence standards for instrument calibration and performance validation (IPV) can be used also to reference fluorescence signals. Of special importance is the reliable and accurate determination of photoluminescence quantum yields (Ф f), that equals the number of emitted per absorbed photons and presents the key performance parameter for emitter efficiency and the comparison of different luminophores. The determination of Ф f is typically done with the aid of so-called quantum yield standards with well-known Ф f values. These standards can also be applied to evaluate integrating sphere setups, which are increasingly being used for absolute measurements of Ф f values. In this respect, division biophotonics of BAM has certificated a set of Ф f standards, which absorb and fluorescence in the wavelength range from 350 to 1100 nm. In the following, the route to Ф f standards with reliable and traceable Ф f values with a complete uncertainty budget will be presented.
T2 - Eurachem-Workshop „Uncertainty from sampling and analysis for accredited laboratories
CY - Berlin, Germany
DA - 19.11.2019
KW - Uncertainty
KW - Fluorescence
KW - Quantum yield standard
KW - Reference Material
PY - 2019
AN - OPUS4-49661
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -