Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (45)
- Zeitschriftenartikel (9)
- Beitrag zu einem Tagungsband (5)
- Posterpräsentation (4)
- Beitrag zu einem Sammelband (3)
- Sonstiges (1)
Sprache
- Englisch (63)
- Deutsch (3)
- Mehrsprachig (1)
Referierte Publikation
- nein (67) (entfernen)
Schlagworte
- Fluorescence (67) (entfernen)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (32)
- 1.2 Biophotonik (31)
- 6 Materialchemie (2)
- 6.1 Oberflächen- und Dünnschichtanalyse (2)
- 1.0 Abteilungsleitung und andere (1)
- 1.1 Anorganische Spurenanalytik (1)
- 4 Material und Umwelt (1)
- 4.2 Material-Mikrobiom Wechselwirkungen (1)
- 6.3 Strukturanalytik (1)
Eingeladener Vortrag
- nein (45)
Steady-state and time-resolved fluorometry of fluorescent pollutants and heavy metal complexes
(1997)
Time-resolved laser-induced fluorescence spectroscopy is one of the most sensitive optical methods which is well suited for on-line in situ analysis. Here, three examples for the steady- state and time-resolved fluorescence analysis of environmentally important analytes, the fluorescent monoaromatic hydrocarbons benzene, toluene, and xylene as well as non fluorescent heavy metal ions forming a fluorescent complex with a cation coordinating fluorescence probe, are presented and the potential of both methods is discussed. For BTX, various mixtures of the spectrally similar compounds B, T, and X showing different fluorescence lifetimes were studied with both methods. As an example for fluorometric metal ion analysis, the fluorescence probe BP(OH)2 (2,2'-bipyridyl- 3,3'-diol) was employed for the determination of d10 metal ions in water and the newly developed fluorescence probe APTA for the detection of Cu(II). Cation complexation of BP(OH2 yields spectrally very similar complexes which differ in their fluorescence lifetimes. Complexation of APTA to Cu(II) leads to small spectral changes and a strong increase in fluorescence quantum yield and lifetime. For the analytes studied, a comparison of the detection limits, standard deviations, and linear dynamic range of both methods clearly demonstrates the analytical potential of time-resolved fluorometry.
Dye-biomolecule conjugates and NIR-fluorescent particles for targeting of disease-related biomarkers
(2011)
Indispensable for fluorescence imaging are highly specific and sensitive molecular probes that absorb and emit in the near infrared (NIR) spectral region and respond to or target molecular species or processes. Here, we present approaches to targeted fluorescent probes for in vivo imaging in the intensity and lifetime domain exploiting NIR dyes. Screening schemes for the fast identification of suitable fluorophores are derived and design criteria for highly emissive optical probes. In addition, as a signal amplification strategy that enables also the use of hydrophobic NIR fluorophores as fluorescent reporters, first steps towards versatile strategies for the preparation of NIR-fluorescent polymeric particles are presented that can be utilized also for the design of targeted and analyte-responsive probes.
We present the synthesis and characterization of multifunctional fluorophore-labeled poly(organosiloxane) nanoparticles with core-shell architecture, where the fluorescent dye is incorporated into the core. Grafting of heterobifunctional poly(ethylene oxide) (PEO) onto the particle surface leads to water-soluble biocompatible nanoparticles. Two different strategies have been used for the synthesis: The encapsulation of dye-labeled monomers during the polycondensation with additional PEO coating and subsequent dye labeling by covalent attachment of the fluorescent dye rhodamine B to the (chloromethylphenyl)siloxane groups in the core after polymerization and grafting of PEO onto the surface. Comparison of the fluorescence quantum yields of the nanoparticles before and after PEO coating show a decrease in quantum yield after PEO coating.
Recent developments of fluorescent probes beyond approved indocyanine green (ICG) – itself increasingly spreading into new imaging applications like lymphatic mapping, arthritis imaging and tumor surgery – exploit various photophysical and biochemical mechanisms to monitor molecular events with higher specificity and accuracy. Emphasizing nanoparticulate formulations, targeted conjugates, activatable probes, probes with a sensor function and multimodality probes, this review discusses advantages and limitations of each type of probe, thereby critically assessing the desired translation into the clinic.
Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools and detection methods for product and process control, material sciences, environmental and bio-technical analysis, molecular genetics, cell biology, medical diagnostics, and drug screening. According to DIN/ISO 17025 certified standards are used for fluorescence diagnostics having the drawback of giving relative values for fluorescence intensities only. Therefore reference materials for a quantitative characterization have to be related directly to the materials under investigation. In order to evaluate these figures it is necessary to calculate absolute numbers like absorption/excitation cross sections and quantum yield. This can be done for different types of dopands in different materials like glass, glass ceramics, crystals or nano crystalline material embedded in polymer matrices. Based on the optical spectroscopy data we will discuss options for characteristic doped glasses and glass ceramics with respect to scattering and absorption regime. It has shown recently for YAG:Ce glass ceramics that for a proper determination of the quantum efficiency in these highly scattering media a reference material with similar scattering and fluorescent properties is required. This may be performed using the emission decay measurement diagnostics, where the decay time is below 100 ns. In this paper we present first results of these aspects using well performing LUMOGEN RED organic pigments for a comparison of mainly transparent glass with glass ceramics doped with various amounts of dopands e.g. ions of raw earth elements and transition metals. The LUMOGEN red is embedded in silica and polyurethane matrices. Characterisations on wavelength accuracy and lifetime for different environmental conditions (temperature, UV irradiation) have been performed. Moreover intensity patterns and results for homogeneity, isotropy, photo and thermal stability will be discussed. In a next step we will show the transfer of the characterisation methods to inorganic fluophores (YAG:Ce) in silicon. Fluorescence (steady state, decay time) and absorption (remission, absorption) spectroscopy working in different temperature regimes (10 - 350 K) are employed diagnostic methods in order to get a microscopic view of the relevant physical processes and to prove the correctness of the obtained data. The work is funded by BMBF under project number 13N8849.
Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools and detection methods for product and process control, material sciences, environmental and biotechnical analysis, molecular genetics, cell biology, medical diagnostics, and drug screening. For routine measurements by fluorescence techniques the existence of an improved quality assurance is one of the basic needs. According to DIN/ISO 17025 certified standards are used for fluorescence diagnostics having the drawback of giving relative values only. Typical requirements onto fluorescence reference materials or standards deal with the verification of the instrument performance as well as the improvement of the data comparability. Especially for biomedical applications fluorescence labels are used for the detection of proteins. In particular these labels consist of nano crystalline materials like CdS and CdSe. The field of Non-Cadmium containing materials is under investigation. In order to evaluate whether glass based materials can be used as standards it is necessary to calculate absolute values like absorption/excitation cross sections or relative quantum yields. This can be done using different quantities of dopands in glass, glass ceramics or crystals. The investigated materials are based on different types of glass, silicate, phosphate and boron glass, which play a dominant role for the absorption and emission mechanism. Additional to the so-called elementary fluorescence properties induced by raw earth elements the formation of defects lead to higher cross sections additionally. The main investigations deal with wavelength accuracy and lifetime of doped glasses, glass ceramics and crystalline samples. Moreover intensity patterns, homogeneity aspects and photo stability will be discussed.
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 not only for standardized test procedures1,2 and for efficient approaches to screen the potential genotoxicity of these materials, but also for standardized and validated methods for surface analysis.
4,5 The analysis and quantification of surface chemistry is hence in the focus of an increasing number of standardization organizations and interlaboratory comparisons with different analytical methods are being done.5 For the monitoring of nanomaterial synthesis and the fast assessment of the number of functional groups such as carboxyl and amino functionalities, which are very commonly used functionalities in the life sciences, simple and validated methods are needed that can be performed with common laboratory instrumentation. 5,6 Here we provide a brief overview of the ongoing research in division Biophotonics employing quantitative NMR (qNMR), conductometry, and colorimetric and fluorometric optical assays for the determination of the total and the accessible number of carboxyl and amino groups on differently sized polymer and silica nano- and microparticles.5-7