TY - JOUR A1 - Karak, Suvendu A1 - Stepanenko, Vladimir A1 - Addicoat, Matthew A. A1 - Keßler, Philipp A1 - Moser, Simon A1 - Beuerle, Florian A1 - Würthner, Frank T1 - A Covalent Organic Framework for Cooperative Water Oxidation JF - Journal of the American Chemical Society N2 - The future of water-derived hydrogen as the “sustainable energy source” straightaway bets on the success of the sluggish oxygen-generating half-reaction. The endeavor to emulate the natural photosystem II for efficient water oxidation has been extended across the spectrum of organic and inorganic combinations. However, the achievement has so far been restricted to homogeneous catalysts rather than their pristine heterogeneous forms. The poor structural understanding and control over the mechanistic pathway often impede the overall development. Herein, we have synthesized a highly crystalline covalent organic framework (COF) for chemical and photochemical water oxidation. The interpenetrated structure assures the catalyst stability, as the catalyst’s performance remains unaltered after several cycles. This COF exhibits the highest ever accomplished catalytic activity for such an organometallic crystalline solid-state material where the rate of oxygen evolution is as high as ∼26,000 μmol L\(^{–1}\) s\(^{–1}\) (second-order rate constant k ≈ 1650 μmol L s\(^{–1}\) g\(^{–2}\)). The catalyst also proves its exceptional activity (k ≈ 1600 μmol L s\(^{–1}\) g\(^{–2}\)) during light-driven water oxidation under very dilute conditions. The cooperative interaction between metal centers in the crystalline network offers 20–30-fold superior activity during chemical as well as photocatalytic water oxidation as compared to its amorphous polymeric counterpart. KW - water oxidation KW - sustainable energy source KW - covalent organic framework KW - catalyst KW - crystalline KW - catalysis KW - nanoparticles Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287591 UR - https://pubs.acs.org/doi/10.1021/jacs.2c07282 SN - 0002-7863 VL - 144 IS - 38 ER - TY - JOUR A1 - Aido, Ahmed A1 - Zaitseva, Olena A1 - Wajant, Harald A1 - Buzgo, Matej A1 - Simaite, Aiva T1 - Anti-Fn14 antibody-conjugated nanoparticles display membrane TWEAK-like agonism JF - Pharmaceutics N2 - Conventional bivalent IgG antibodies targeting a subgroup of receptors of the TNF superfamily (TNFSF) including fibroblast growth factor-inducible 14 (anti-Fn14) typically display no or only very limited agonistic activity on their own and can only trigger receptor signaling by crosslinking or when bound to Fcγ receptors (FcγR). Both result in proximity of multiple antibody-bound TNFRSF receptor (TNFR) molecules, which enables engagement of TNFR-associated signaling pathways. Here, we have linked anti-Fn14 antibodies to gold nanoparticles to mimic the “activating” effect of plasma membrane-presented FcγR-anchored anti-Fn14 antibodies. We functionalized gold nanoparticles with poly-ethylene glycol (PEG) linkers and then coupled antibodies to the PEG surface of the nanoparticles. We found that Fn14 binding of the anti-Fn14 antibodies PDL192 and 5B6 is preserved upon attachment to the nanoparticles. More importantly, the gold nanoparticle-presented anti-Fn14 antibody molecules displayed strong agonistic activity. Our results suggest that conjugation of monoclonal anti-TNFR antibodies to gold nanoparticles can be exploited to uncover their latent agonism, e.g., for immunotherapeutic applications. KW - Fn14 KW - nanoparticles KW - surface modification KW - drug-delivery KW - anti-TNFRSF receptor (TNFR) antibodies Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-242710 SN - 1999-4923 VL - 13 IS - 7 ER - TY - JOUR A1 - Brachner, Andreas A1 - Fragouli, Despina A1 - Duarte, Iola F. A1 - Farias, Patricia M. A. A1 - Dembski, Sofia A1 - Ghosh, Manosij A1 - Barisic, Ivan A1 - Zdzieblo, Daniela A1 - Vanoirbeek, Jeroen A1 - Schwabl, Philipp A1 - Neuhaus, Winfried T1 - Assessment of human health risks posed by nano-and microplastics is currently not feasible JF - International Journal of Environmental Research and Public Health N2 - The exposure of humans to nano-and microplastic particles (NMPs) is an issue recognized as a potential health hazard by scientists, authorities, politics, non-governmental organizations and the general public. The concentration of NMPs in the environment is increasing concomitantly with global plastic production and the usage of plastic materials. NMPs are detectable in numerous aquatic organisms and also in human samples, therefore necessitating a risk assessment of NMPs for human health. So far, a comprehensive risk assessment of NMPs is hampered by limited availability of appropriate reference materials, analytical obstacles and a lack of definitions and standardized study designs. Most studies conducted so far used polystyrene (PS) spheres as a matter of availability, although this polymer type accounts for only about 7% of total plastic production. Differently sized particles, different concentration and incubation times, and various biological models have been used, yielding hardly comparable data sets. Crucial physico-chemical properties of NMPs such as surface (charge, polarity, chemical reactivity), supplemented additives and adsorbed chemicals have been widely excluded from studies, although in particular the surface of NMPs determines the interaction with cellular membranes. In this manuscript we give an overview about the critical parameters which should be considered when performing risk assessments of NMPs, including novel reference materials, taking into account surface modifications (e.g., reflecting weathering processes), and the possible role of NMPs as a substrate and/or carrier for (pathogenic) microbes. Moreover, we make suggestions for biological model systems to evaluate immediate toxicity, long-term effects and the potential of NMPs to cross biological barriers. We are convinced that standardized reference materials and experimental parameters along with technical innovations in (nano)-particle sampling and analytics are a prerequisite for the successful realization of conclusive human health risk assessments of NMPs. KW - nanoplastics KW - nanoparticles KW - microplastics KW - microparticles KW - human exposure KW - biological barriers KW - biofilm KW - microbe carrier KW - toxicity KW - neurotoxicity Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219423 SN - 1660-4601 VL - 17 IS - 23 ER - TY - JOUR A1 - Vogel, Patrick A1 - Rückert, Martin Andreas A1 - Friedrich, Bernhard A1 - Tietze, Rainer A1 - Lyer, Stefan A1 - Kampf, Thomas A1 - Hennig, Thomas A1 - Dölken, Lars A1 - Alexiou, Christoph A1 - Behr, Volker Christian T1 - Critical Offset Magnetic PArticle SpectroScopy for rapid and highly sensitive medical point-of-care diagnostics JF - Nature Communications N2 - Magnetic nanoparticles (MNPs) have been adapted for many applications, e.g., bioassays for the detection of biomarkers such as antibodies, by controlled engineering of specific surface properties. Specific measurement of such binding states is of high interest but currently limited to highly sensitive techniques such as ELISA or flow cytometry, which are relatively inflexible, difficult to handle, expensive and time-consuming. Here we report a method named COMPASS (Critical-Offset-Magnetic-Particle-SpectroScopy), which is based on a critical offset magnetic field, enabling sensitive detection to minimal changes in mobility of MNP ensembles, e.g., resulting from SARS-CoV-2 antibodies binding to the S antigen on the surface of functionalized MNPs. With a sensitivity of 0.33 fmole/50 µl (≙7 pM) for SARS-CoV-2-S1 antibodies, measured with a low-cost portable COMPASS device, the proposed technique is competitive with respect to sensitivity while providing flexibility, robustness, and a measurement time of seconds per sample. In addition, initial results with blood serum demonstrate high specificity. KW - biochemical assays KW - characterization and analytical techniques KW - magnetic properties and materials KW - nanoparticles Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300893 VL - 13 ER - TY - JOUR A1 - Radeloff, Katrin A1 - Radeloff, Andreas A1 - Tirado, Mario Ramos A1 - Scherzad, Agmal A1 - Hagen, Rudolf A1 - Kleinsasser, Norbert H. A1 - Hackenberg, Stephan T1 - Long-Term Impact of Zinc Oxide Nanoparticles on Differentiation and Cytokine Secretion of Human Adipose-Derived Stromal Cells JF - Materials N2 - Zinc oxide nanoparticles (ZnO-NPs) are widely utilized, for example in manufacturing paints and in the cosmetic industry. In addition, there is raising interest in the application of NPs in stem cell research. However, cytotoxic, genotoxic and pro-inflammatory effects were shown for NPs. The aim of this study was to evaluate the impact of ZnO-NPs on cytokine secretion and differentiation properties of human adipose tissue-derived stromal cells (ASCs). Human ASCs were exposed to the subtoxic concentration of 0.2 mu g/mL ZnO-NPs for 24 h. After four weeks of cultivation, adipogenic and osteogenic differentiation procedures were performed. The multi-differentiation potential was confirmed histologically and using polymerase chain reaction (PCR). In addition, the gene expression of IL-6, IL-8, vascular endothelial growth factor (VEGF) and caspase 3 was analyzed. Over the course of four weeks after ZnO-NPs exposure, no significant differences were detected in the gene expression of IL-6, IL-8, VEGF and caspase 3 compared to non-exposed cells. The differentiation was also not affected by the ZnO-NPs. These findings underline the fact, that functionality of ASCs is likely to be unaffected by ZnO-NPs, despite a long-term disposition of NPs in the cells, supposing that the starting concentration was safely in the non-toxic range. This might provide important information for single-use nanomedical applications of ZnO-NPs. KW - zinc oxide KW - nanoparticles KW - toxicity KW - differentiation potential KW - human adipose-derived stromal cells KW - stem cells Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224779 VL - 12 IS - 1823 ER - TY - JOUR A1 - Han, Luyang A1 - Wiedwald, Ulf A1 - Biskupek, Johannes A1 - Fauth, Kai A1 - Kaiser, Ute A1 - Ziemann, Paul T1 - Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films JF - Beilstein Journal of Nanotechnology N2 - The thermally activated formation of nanoscale CoPt alloys was investigated, after deposition of self-assembled Co nanoparticles on textured Pt(111) and epitaxial Pt(100) films on MgO(100) and SrTiO3(100) substrates, respectively. For this purpose, metallic Co nanoparticles (diameter 7 nm) were prepared with a spacing of 100 nm by deposition of precursor-loaded reverse micelles, subsequent plasma etching and reduction on flat Pt surfaces. The samples were then annealed at successively higher temperatures under a H2 atmosphere, and the resulting variations of their structure, morphology and magnetic properties were characterized. We observed pronounced differences in the diffusion and alloying of Co nanoparticles on Pt films with different orientations and microstructures. On textured Pt(111) films exhibiting grain sizes (20–30 nm) smaller than the particle spacing (100 nm), the formation of local nanoalloys at the surface is strongly suppressed and Co incorporation into the film via grain boundaries is favoured. In contrast, due to the absence of grain boundaries on high quality epitaxial Pt(100) films with micron-sized grains, local alloying at the film surface was established. Signatures of alloy formation were evident from magnetic investigations. Upon annealing to temperatures up to 380 °C, we found an increase both of the coercive field and of the Co orbital magnetic moment, indicating the formation of a CoPt phase with strongly increased magnetic anisotropy compared to pure Co. At higher temperatures, however, the Co atoms diffuse into a nearby surface region where Pt-rich compounds are formed, as shown by element-specific microscopy. KW - alloy KW - CoPt KW - HRTEM KW - nanoparticles KW - XMCD KW - Co KW - epitaxy KW - magnetometry KW - Pt Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-142869 VL - 2 ER - TY - THES A1 - Joshi, Sanjeev T1 - Preparation and characterization of CdS nanoparticles T1 - DPräparat und characktereisierung von CdS Nanopartikeln N2 - Zusammenfassung CdS-Nanoteilchen mit Größen zwischen 1.1 und 4.2 nm wurden in Äthanol und mit Thioglycerol (TG)-Hülle synthetisiert. Es wurde gezeigt, dass die nass-chemische Synthese ohne Wasser und die Verwendung von TG als Hülle folgende Vorteile bieten: Es konnten kleinere Teilchen hergestellt und eine schmalere Größenverteilung erzielt werden. Zusätzlich wird dem Altern der Teilchen vorgebeugt, und die Ergebnisse sind besser reproduzierbar. Hochaufgelöste Photoemissions-Messungen an kleinen CdS-Teilchen (1.1, 1.4, 1.7, 1.8; 1.8 nm mit Glutathion-Hülle) ergaben Beiträge von fünf verschiedenen Schwefelatom-Typen zum S 2p-Gesamt Signal. Außerdem wurde beobachtet, dass Nanoteilchen unterschiedlicher Größe und/oder mit unterschiedlichen Hüllen-Substanzen verschiedene Photoemissionsspektren zeigen und verschieden starke Strahlenschäden aufweisen. Bei den 1.4 nm großen CdS-Teilchen entsprechen die Komponenten des S 2p-Signals entweder Schwefelatomen mit unterschiedlichen Cd-Nachbarn, Thiol-Schwefelatomen oder teilweise oxidiertem Schwefel. Die jeweilige Zuweisung der Schwefeltypen erfolgte über Intensitäts-Änderungen der einzelnen S 2p-Komponenten als Funktion der Photonenenergie und des Strahlenschadens. Die Daten der 1.4 nm großen CdS-Teilchen wurden mit PES-Intensitäts-Rechnungen verglichen, die auf einem neuen Strukturmodell-Ansatz basieren. Von den drei verwendeten CdS-Strukturmodellen konnte nur ein Modell mit 33 S-Atomen die Variation der experimentellen Intensitäten richtig wieder geben. Modelle von größeren Nanoteilchen mit beispielsweise 53 S-Atomen zeigen Abweichungen von den experimentellen Daten der 1.4 nm-Teilchen. Auf diese Weise kann indirekt auf die Größe der gemessenen Teilchen geschlossen werden. Die Intensitätsrechnungen wurden zum einen „per Hand“ zur groben Abschätzung durchgeführt, zum anderen wurden exaktere Berechnungen mit einem von L. Weinhardt und O. Fuchs entwickelten Programm angestellt. Diese bestätigen die Ergebnisse der Abschätzung. Zudem wurde festgestellt, dass die inelastische freie Weglänge λ keinen signifikanten Einfluss auf die Modellrechnungen hat. Die gemessenen Intensitäts-Änderungen konnten zwar mit mehreren leicht verchiedenen Modellen erklärt werden, allerdings führte nur ein kugelförmiges Teilchen-Modell auch zu den richtigen Intensitätsverhältnissen der einzelnen S 2p-Komponenten. Weiterhin konnte beobachtet werden, dass die elektronische Bandlücke größer ist als die optische Bandlücke. Bei den PES-Messungen wurden einige wichtige Einflüsse sichtbar. So spielen strahlenbedingte Effekte eine große Rolle. Kenntnisse über die Zeitskala solcher Effekte ermöglichen PES-Aufnahmen mit guter Signal-Qualität und erlauben eine Extraploation zur Situation ohne Strahlenschaden. Auch die Dünnschicht-Präparation beeinflusst die Spektren. Beispielsweise zeigten mit Elektrophorese hergestellte Filme Hinweise auf Agglomeration. Schichten, die per Tropfen-Deposition erzeugt wurden, weisen spektrale Änderungen am Rand der Probe auf, und Filme aus Nanoteilchen-Pulver waren nicht homogen. Mikro-Raman Experimente, die in Kollaboration mit Dr. M. Schmitt und Prof. W. Kiefer durchgeführt wurden, ließen große Unterschiede in den Spektren von Nanoteilchen und TG in Lösung erkennen. Dies wurde vor allem auf das Fehlen von S – H –Bindungen zurückgeführt und zeigt damit, dass alle TG-Moleküle verwertet oder ausgewaschen wurden. N2 - Very small, thioglycerol (TG)-capped CdS nanoparticles were synthesized by a wet chemical technique and investigated in the framework of this thesis. Also glutathione-capped particles were investigated for a comparison of the capping agents. High-resolution photoelectron spectroscopy using high-brilliance synchrotron radiation was applied as the major tool for the characterization of these particles. Additionally, the particles were investigated with UV-VIS absorption spectroscopy, XPS using a laboratory source, valence band photoemission spectroscopy (VBPES), near-edge x-ray absorption spectroscopy (NEXAFS), and micro-Raman spectroscopy to address various aspects of the particles. In the beginning, an overview on size quantization effects is given to create a theoretical background behind the work presented in this thesis. Furthermore, an overview of various conventional techniques for size determination is presented. Exact information about size, shape and size distribution of nanoparticles is not yet achievable because of experimental limitations of the various size determination methods. Nanoparticles, with a range of sizes from 1.1 to 4. 2 nm, were synthesized using non-aqueous preparation and a TG capping. It is demonstrated that the use of the non-aqueous wet chemical synthesis method enables the production of very small particles and prohibits the aging of the particles. Furthermore, TG capping leads to a significant improvement for a narrow size distribution. Moreover, the results are very reproducible with TG capping and non-aqueous synthesis. Monodispersed particles can be produced by a size selective precipitation method, however, the reproducibility is questionable due to the aqueous medium of the synthesis in this case. High-resolution photoemission measurements on the small particles, i.e., 1.1 nm (CdS-A), 1.4 nm (CdS-B), 1.7 nm (CdS-C), and 1.8 nm (CdS-D, glutathione-capped), revealed five components as constituents of the S 2p signal after a careful data evaluation. Furthermore, it was observed that the particles with different sizes and capping show differences in the photoemission spectra and also in the beam damage behaviour. The different components of CdS-B were assigned as S atoms with different Cd neighbors, S atoms from thiol and S atoms in a partially oxidized state, based on the observed intensity changes of these components as a function of photon energy and beam damage, and on previous photoemission work on CdS nanoparticles [23, 45]. Furthermore, it was found that this assignment cannot be directly transferred to other particles. A new approach of structural model-based photoemission intensity calculations in comparison with the experimental data is presented. This enables us to understand subtle features in the photoemission spectra, in particular the intensity changes of the different components as a function of photon energy and beam exposure. This approach is especially applied to CdS-B (as some structural information for this particle is avialable from XRD), using three different structural models. It is found that a structural model with 33 S atoms can explain the experimental intensity changes of CdS-B. Furthermore, it is found that the photoemission spectra can be used to determine the particle size indirectly, as other plausible models show significant deviation from the experimental data. To study the various aspects by calculations, such as the influence of the particle shape and of the value of the mean free path, a program developed with L. Weinhardt and O. Fuchs is used for the intensity calculations. In order to determine a reasonable value of the mean free path for the used photon energies, two different equations from previous reports (Seah et al. and Powell et al.) are applied. As average mean free path values for the two photon energies we chose 5.5 ± 2 Å (254 eV) and 14 ± 2 Å (720 eV). The program calculation confirms the result of simple “manual” calculations of the different models. Moreover, it is tested that the value of , used in the calculations does not produce any significant influence on the calculation results. Another interesting feature is derived from the calculations that a model with a rather round shape produces similar intensity ratios for the different components to those of the data. Thus this new approach of analysis of photoemission spectra offers a way to determine particle sizes and to some extent to give an impression of the approximate particle shape. Furthermore, it is observed that the electronic band gap is larger compared to the optical band gap, which was attributed to an enhanced electron-hole correlation for optical absorption in small particles. The XPS experiments performed in the laboratory using an x-ray tube, show that the thin films produced from a freshly synthesized nanoparticle solution are fairly homogeneous and non-charging. Moreover, annealing experiments indicated that TG-capped particles posses less thermal stability as compared to MPA-capped particles. It was demonstrated that beam-induced effects play a major role. However, the knowledge of the time scale for such effects gives the possibility to record photoemission spectra with fairly good signal quality and to extrapolate to zero radiation damage. Further, particles with different sizes and capping show different beam damage behaviour. The thin film preparation by electrophoresis results in significant changes in the spectrum indicating agglomeration, while the drop-deposition technique points towards spectral changes on the rim of the sample, which can be avoided by focusing the radiation to the centre of the deposited dried drop. Micro-Raman experiments carried out in collaboration with C. Dem, Dr. M. Schmitt and Prof. W. Kiefer exhibited major differences in the spectra of nanoparticles as compared to those of the capping molecule thioglycerol. For instance, the absence of the S-H vibrational modes indicates the consumption or removal of all unreacted capping molecules. There is definitely a need for further detailed investigations concerning various interesting aspects of this work. For instance, it would be of significance to extend the program calculations to more models. Also more information about the band gap opening has to be gathered in order to find out the reason for the larger electronic band gap as compared to the optical band gap. The photoemission analysis approach using a model calculation has to be extended to differently prepared nanoparticles, in particular, to address the differences in the location of the various species in the particle as a function of preparation. The efforts of XRD simulations by C. Kumpf et al. [50] may reveal significant new information about the particle size and the size distribution. It can be expected that the program calculations, if extended to more models, can prove the potential of photoelectron spectroscopy to serve as a tool for size and shape determination of nanoparticles, which is a new contribution to the investigation of nanoparticles. KW - Cadmiumsulfid KW - Nanopartikel KW - Nanopartikel KW - Photoemission KW - XRD KW - UV-VIS KW - nanoparticles KW - XPS KW - monodispersity KW - UV-VIS KW - Photoemission Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-13395 ER - TY - JOUR A1 - Ickrath, Pascal A1 - Wagner, Martin A1 - Scherzad, Agmal A1 - Gehrke, Thomas A1 - Burghartz, Marc A1 - Hagen, Rudolf A1 - Radeloff, Katrin A1 - Kleinsasser, Norbert A1 - Hackenberg, Stephan T1 - Time-Dependent Toxic and Genotoxic Effects of Zinc Oxide Nanoparticles after Long-Term and Repetitive Exposure to Human Mesenchymal Stem Cells JF - International Journal of Environmental Research and Public Health N2 - Zinc oxide nanoparticles (ZnO-NP) are widely spread in consumer products. Data about the toxicological characteristics of ZnO-NP is still under controversial discussion. The human skin is the most important organ concerning ZnO-NP exposure. Intact skin was demonstrated to be a sufficient barrier against NPs; however, defect skin may allow NP contact to proliferating cells. Within these cells, stem cells are the most important toxicological target for NPs. The aim of this study was to evaluate the genotoxic and cytotoxic effects of ZnO-NP at low-dose concentrations after long-term and repetitive exposure to human mesenchymal stem cells (hMSC). Cytotoxic effects of ZnO-NP were measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Furthermore, genotoxicity was evaluated by the comet assay. For long-term observation over 6 weeks, transmission electron microscopy (TEM) was applied. The results of the study indicated cytotoxic effects of ZnO-NP beginning at high concentrations of 50 μg/mL and genotoxic effects in hMSC exposed to 1 and 10 μg/mL ZnO-NP. Repetitive exposure enhanced cyto- but not genotoxicity. Intracellular NP accumulation was observed up to 6 weeks. The results suggest cytotoxic and genotoxic potential of ZnO-NP. Even low doses of ZnO-NP may induce toxic effects as a result of repetitive exposure and long-term cellular accumulation. This data should be considered before using ZnO-NP on damaged skin. KW - zinc oxide KW - ZnO KW - nanoparticles KW - cytotoxicity KW - toxicity KW - genotoxicity Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169932 VL - 14 IS - 12 ER - TY - JOUR A1 - Radeloff, Katrin A1 - Radeloff, Andreas A1 - Ramos Tirado, Mario A1 - Scherzad, Agmal A1 - Hagen, Rudolf A1 - Kleinsasser, Norbert H. A1 - Hackenberg, Stephan T1 - Toxicity and functional impairment in human adipose tissue-derived stromal cells (hASCs) following long-term exposure to very small iron oxide particles (VSOPs) JF - Nanomaterials N2 - Magnetic nanoparticles (NPs), such as very small iron oxide NPs (VSOPs) can be used for targeted drug delivery, cancer treatment or tissue engineering. Another important field of application is the labelling of mesenchymal stem cells to allow in vivo tracking and visualization of transplanted cells using magnetic resonance imaging (MRI). For these NPs, however, various toxic effects, as well as functional impairment of the exposed cells, are described. The present study evaluates the influence of VSOPs on the multilineage differentiation ability and cytokine secretion of human adipose tissue derived stromal cells (hASCs) after long-term exposure. Human ASCs were labelled with VSOPs, and the efficacy of the labelling was documented over 4 weeks in vitro cultivation of the labelled cells. Unlabelled hASCs served as negative controls. Four weeks after labelling, adipogenic and osteogenic differentiation was histologically evaluated and quantified by polymerase chain reaction (PCR). Changes in gene expression of IL-6, IL-8, VEGF and caspase 3 were determined over 4 weeks. Four weeks after the labelling procedure, labelled and unlabelled hASCs did not differ in the gene expression of IL-6, IL-8, VEGF and caspase 3. Furthermore, the labelling procedure had no influence on the multidifferentiation ability of hASC. The percentage of labelled cells decreased during in vitro expansion over 4 weeks. Labelling with VSOPs and long-term intracellular disposition probably have no influence on the physiological functions of hASCs. This could be important for the future in vivo use of iron oxide NPs. KW - iron oxide nanoparticles KW - VSOP KW - nanoparticles KW - toxicity KW - differentiation potential KW - human adipose-derived stromal cells KW - stem cells KW - long-term exposure Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-203676 SN - 2079-4991 VL - 10 IS - 4 ER -