TY - CONF A1 - Wegner, Karl David A1 - Coro, A. A1 - Le Guevel, X. A1 - Juarez, B. H. A1 - Resch-Genger, Ute 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 - JOUR A1 - Wegner, Karl David A1 - Resch-Genger, Ute T1 - The 2023 Nobel Prize in Chemistry: Quantum dots JF - Analytical and Bioanalytical Chemistry N2 - The 2023 Nobel Prize in Chemistry was awarded to Aleksey I. Ekimov (prize share 1/3), Louis E. Brus (prize share 1/3), and Moungi G. Bawendi (prize share 1/3) for groundbreaking inventions in the field of nanotechnology, i.e., for the discovery and synthesis of semiconductor nanocrystals, also termed quantum dots, that exhibit size-dependent physicochemical properties enabled by quantum size effects. This feature article summarizes the main milestones of the discoveries and developments of quantum dots that paved the road to their versatile applications in solid-state lighting, display technology, energy conversion, medical diagnostics, bioimaging, and image-guided surgery. KW - Quantum dots KW - Semiconductor nanocrystals KW - Luminescence KW - Quantitative spectroscopy KW - Quantum yield KW - Advanced nanomaterials KW - Quality assurance KW - Energy transfer PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597843 DO - https://doi.org/10.1007/s00216-024-05225-9 VL - 2024 SP - 1 EP - 11 PB - Springer CY - Cham AN - OPUS4-59784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David A1 - Coro, A. A1 - Marquez, R. M. A1 - Le Guevel, X. A1 - Juarez, B. H. A1 - Resch-Genger, Ute 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 - CONF A1 - Matiushkina, Anna A1 - Litvinov, I. A1 - Bazhenova, A. A1 - Belyaeva, T. A1 - Dubavik, A. A1 - Veniaminov, A. A1 - Maslov, V. A1 - Kornilova, E. A1 - Orlova, A. A1 - Tavernaro, Isabella A1 - Andresen, Elina A1 - Prinz, Carsten A1 - Resch-Genger, Ute T1 - Synthesis and physical properties studies of bifunctional nanocomposites N2 - At present, the field of research on nanostructures is actively developing, which is due to their unique physico-chemical properties compared to bulk materials. Many research activities are focused on obtaining nanocomposites, which combine various types of nanostructures with different properties and function. For example, the development of magneto-luminescent nanocomposites makes it possible to use their luminescence for optical imaging, and their magnetic properties for magnetic targeted delivery and as agents of hyperthermia and magnetic resonance imaging. My master studies as part of the project Goszadanie 2019-1080 at ITMO were focused on the investigation of nanocomposites, consisting of semiconductor quantum dots (QDs) as luminescent component and superparamagnetic iron oxide nanoparticles (SPIONs) as magnetic one, in solution and during their incubation with HeLa cells. The spectrally resolved analysis of the QD photoluminescence (PL) kinetics of the free QDs and the QDs incorporated in these nanocomposites undergoing energy transfer processes allowed for (1) understanding the reasons for the quenching of QD luminescence in cells, (2) evaluating the average distance between the QDs and, based on this, concluding the degree of QD aggregation in cells, and (3) drawing conclusions about the QD-quencher composites integrity in cells. Overall, the analysis of the PL kinetics confirmed that QDs and SPIONs remain bound in the obtained nanocomposites during incubation with cells. To ensure the successful advancement of nanomaterials in biomedicine and the transition from their laboratory preparation and studies to their use in different applications and in industry, it is crucial to develop reliable measurement methods and reference materials candidates for the characterization of functional nanomaterials and assessing the quality of the obtained nanostructures. My recently started project at BAM, which is part of the EU metrology project MeTrINo, will be devoted to this topic. There we will focus on the development of methodologies for the synthesis and characterization of iron oxide nanoparticles, already used in biomedicine, and multi-element lanthanide-based nanoparticles with attractive upconversion luminescence, as reference materials with high monodispersity and reproducibility. Also, these nanoparticles will be functionalized with organic dyes for optical imaging and, probably, the study of the energy transfer phenomena. T2 - Bad Honnef Summer School CY - Bad Honnef, Germany DA - 30.07.2023 KW - Quantum dots KW - Iron oxide nanoparticles KW - Upconversion nanoparticles PY - 2023 AN - OPUS4-58075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krauss, S. W. A1 - Eckardt, M. A1 - Will, J. A1 - Spiecker, E. A1 - Siegel, R. A1 - Dulle, M. A1 - Schweins, R. A1 - Pauw, Brian Richard A1 - Senker, J. A1 - Zobel, M. T1 - H-D-isotope effect of heavy water affecting ligand-mediated nanoparticle formation in SANS and NMR experiments JF - Nanoscale N2 - An isotopic effect of normal (H2O) vs. heavy water (D2O) is well known to fundamentally affect structure and chemical properties of proteins, for instance. Here we correlate results from small angle X-ray and neutron scattering (SAXS, SANS) with high-resolution scanning transmission electron microscopy to track the evolution of CdS nanoparticle size and crystallinity from aqeuous solution in presence of the organic ligand ethylenediaminetetraacetate (EDTA) at room temperature in both H2O and D2O. We provide evidence via SANS experiments that exchanging H2O by D2O impacts nanoparticle formation by changing the equilibria and dynamics of EDTA clusters in solution as investigated by nuclear magnetic resonance. The colloidal stability of the CdS nanoparticles, covered by a layer of [Cd(EDTA)]2- complexes, is significantly reduced in D2O despite the strong stabilizing effect of EDTA in suspensions of normal water. Hence, conclusions about nanoparticle formation mechanisms from D2O solutions can bare limited transferability to reactions in normal water due to isotopic effects, which thus need to be discussed for contrast match experiments. KW - General Materials Science KW - Quantum dots KW - CdS KW - Deuterium KW - X-ray scattering KW - MOUSE PY - 2023 DO - https://doi.org/10.1039/D3NR02419A SN - 2040-3364 VL - 15 IS - 40 SP - 16413 EP - 16424 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scholtz, Lena A1 - Tavernaro, Isabella A1 - Eckert, J. G. A1 - Lutowski, Marc A1 - Hertwig, Andreas A1 - Hidde, Gundula A1 - Bigall, N. C. A1 - Resch-Genger, Ute 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 - Scholtz, Lena A1 - Eckert, J. G. A1 - Elahi, T. A1 - Lübkemann, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Luminescence encoding of polymer microbeads with organic dyes and semiconductor quantum dots during polymerization JF - Scientific reports N2 - Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5–2.5 μm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate. KW - Polymerization KW - Quantum dots KW - Microbeads KW - Fluorescence PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-553430 DO - https://doi.org/10.1038/s41598-022-16065-x SN - 2045-2322 VL - 12 SP - 1 EP - 16 PB - Nature Publishing Group CY - London AN - OPUS4-55343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scholtz, Lena A1 - Eckert, J. G. A1 - Lübkemann-Warwas, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute 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 - CONF A1 - Scholtz, Lena A1 - Eckert, J. G. A1 - Elahi, T. A1 - Lübkemann, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Luminescence Encoding of Polymer Microbeads during Polymerization N2 - Differently sized, luminescent polymer beads encoded with QDs were prepared with a simple, optimized procedure. The optical properties of the resulting particles were studied to ensure sufficient fluorescence and to evaluate the influence of the polymerization on QD fluorescence. T2 - 84th Prague Meeting on Macromolecules - Frontiers of Polymer Colloids CY - Prague, Czech Republic DA - 24.07.2022 KW - Polymerization KW - Fluorescence KW - Quantum dots KW - Microbeads PY - 2022 AN - OPUS4-55447 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Miropoltsev, M. A1 - Wegner, Karl David A1 - Häusler, I. A1 - Hodoroaba, Vasile-Dan A1 - Resch-Genger, Ute T1 - Influence of Hydrophilic Thiol Ligands of Varying Denticity on the Luminescence Properties and Colloidal Stability of Quaternary Semiconductor Nanocrystals JF - Journal of Physical Chemistry C N2 - Binary photoluminescent semiconductor nanocrystals (quantum dots, QDs) are one of the best studied fluorescent nanomaterials, and their unique optoelectronic properties paved the road to many applications in (bio)nanophotonics, optoelectronics, and photovoltaics. However, concerns related to their toxic constituents like cadmium or lead and the emerging interest in greener chemistry synthesis approaches hamper their future applicability. Interesting alternatives for some applications like biosensing or bioimaging are heavy-metal-free ternary QDs like AgInS2 (AIS), CuInS2 (CIS), and quaternary QDs such as AIS-ZnS (ZAIS). In this context, we explored the effect of ligand denticity on the organic-to-aqueous phase transfer of oleylamine-stabilized ZAIS QDs with the hydrophilic ligands mercaptopropionic acid (MPA), dihydrolipoic acid (DHLA), and 3-mercapto-2,2-bis(mercaptomethyl)propanoic acid (3MPA), bearing mono-, bi-, and trialkyl thiol groups. Spectroscopic studies of the resulting water-dispersible ZAIS QDs revealed a considerable influence of ligand denticity and ligand-to-QD ratio on the spectral position and width (FWHM; full width at half-maximum) of the photoluminescence (PL) bands, the PL quantum yields (PL QY), and the PL decay kinetics. Thiol capping and phase transfer resulted in a loss in PL by at least a factor of 2. The ligand-induced PL quenching observed particularly for ligands bearing two or three thiol groups was attributed to the facilitated formation of surface-bound disulfides. The best colloidal stability under high dilution conditions was observed for 3MPA. KW - Quantum dots KW - Ligand exchange KW - Lifetime analysis KW - Thiols PY - 2022 DO - https://doi.org/10.1021/acs.jpcc.2c05342 SN - 1932-7447 VL - 126 IS - 47 SP - 20101 EP - 20113 PB - ACS Publications AN - OPUS4-56707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -