TY - JOUR A1 - Afantitis, A. A1 - Melagraki, G. A1 - Isigonis, P. A1 - Tsoumanis, A. A1 - Varsou, D. D. A1 - Valsami-Jones, E. A1 - Papadiamantis, A. A1 - Ellis, L.-J. A. A1 - Sarimveis, H. A1 - Doganis, P. A1 - Karatzas, P. A1 - Tsiros, P. A1 - Liampa, I. A1 - Lobaskin, V. A1 - Greco, D. A1 - Serra, A. A1 - Kinaret, P. A. S. A1 - Saarimäki, L. A. A1 - Grafström, R. A1 - Kohonen, P. A1 - Nymark, P. A1 - Willighagen, E. A1 - Puzyn, T. A1 - Rybinska-Fryca, A. A1 - Lyubartsev, A. A1 - Jensen, K. A. A1 - Brandenburg, J. G. A1 - Lofts, S. A1 - Svendsen, C. A1 - Harrison, S. A1 - Maier, D. A1 - Tamm, K. A1 - Jänes, J. A1 - Sikk, L. A1 - Dusinska, M. A1 - Longhin, E. A1 - Rundén-Pran, E. A1 - Mariussen, E. A1 - El Yamani, N. A1 - Unger, Wolfgang A1 - Radnik, Jörg A1 - Tropsha, A. A1 - Cohen, Y. A1 - Lesczynski, J. A1 - Hendren, C. O. A1 - Wiesner, M. A1 - Winkler, D. A1 - Suzuki, N. A1 - Yoon, T. H. A1 - Choi, J.-S. A1 - Sanabria, N. A1 - Gulumian, M. A1 - Lynch, I. T1 - NanoSolveIT Project: Driving nanoinformatics research to develop innovative and integrated tools for in silico nanosafety assessment N2 - Nanotechnology has enabled the discovery of a multitude of novel materials exhibiting unique physicochemical (PChem) properties compared to their bulk analogues. These properties have led to a rapidly increasing range of commercial applications; this, however, may come at a cost, if an association to long-term health and environmental risks is discovered or even just perceived. Many nanomaterials (NMs) have not yet had their potential adverse biological effects fully assessed, due to costs and time constraints associated with the experimental assessment, frequently involving animals. Here, the available NM libraries are analyzed for their suitability for integration with novel nanoinformatics approaches and for the development of NM specific Integrated Approaches to Testing and Assessment (IATA) for human and environmental risk assessment, all within the NanoSolveIT cloud-platform. These established and well-characterized NM libraries (e.g. NanoMILE, NanoSolutions, NANoREG, NanoFASE, caLIBRAte, NanoTEST and the Nanomaterial Registry (>2000 NMs)) contain physicochemical characterization data as well as data for several relevant biological endpoints, assessed in part using harmonized Organisation for Economic Co-operation and Development (OECD) methods and test guidelines. Integration of such extensive NM information sources with the latest nanoinformatics methods will allow NanoSolveIT to model the relationships between NM structure (morphology), properties and their adverse effects and to predict the effects of other NMs for which less data is available. The project specifically addresses the needs of regulatory agencies and industry to effectively and rapidly evaluate the exposure, NM hazard and risk from nanomaterials and nano-enabled products, enabling implementation of computational ‘safe-by-design’ approaches to facilitate NM commercialization. KW - Nanoinformatics KW - Hazard assessment KW - (Quantitative) Structure-Active Relationships KW - Safe-by-design KW - Predictive modelling PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505952 DO - https://doi.org/10.1016/j.csbj.2020.02.023 VL - 18 SP - 583 EP - 602 PB - Elsevier B.V. AN - OPUS4-50595 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ahmed, R. A1 - Vaishampayan, A. A1 - Cuellar-Camacho, J. L. A1 - Wight, D. J. A1 - Donskyi, Ievgen A1 - Unger, Wolfgang A1 - Grohmann, E. A1 - Haag, R. A1 - Wagner, O. T1 - Multivalent Bacteria Binding by Flexible Polycationic Microsheets Matching Their Surface Charge Density N2 - Aiming at the overall negative surface charge of bacteria, a new strategy of antibacterial agents based on large polymer-modified graphene oxide (GO) sheets is assessed. The presented flexible, polycationic Sheets match the size and charge density of the Escherichia coli surface charge density (2 × 1014 cm−2). These matching parameters create an unspecific but very strong bacteria adsorber by multivalent, electrostatic attraction. Their interaction with bacteria is visualized via atomic force and confocal microscopy and shows that they effectively bind and wrap around E. coli cells, and thereby immobilize them. The incubation of Gram-negative and -positive bacteria (E. coli and methicillin-resistant Staphylococcus aureus, MRSA) with these polycationic sheets leads to the inhibition of proliferation and a reduction of the colony forming bacteria over time. This new type of antibacterial agent acts in a different mode of Action than classical biocides and could potentially be employed in medicinal, technical, or agriculture applications. The presented microsheets and their unspecific binding of cell interfaces could further be employed as adsorber material for bacterial filtration or immobilization for imaging, analysis, or sensor technologies. KW - Surface charge KW - Bacteria KW - Graphene oxide KW - Escherichia coli KW - XPS PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509651 DO - https://doi.org/10.1002/admi.201902066 VL - 7 IS - 15 SP - 1902066 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-50965 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baer, D. R. A1 - Karakoti, A. S. A1 - Clifford, C. A. A1 - Minelli, C. A1 - Unger, Wolfgang T1 - Importance of sample preparation on reliable surface characterisation of nano‐objects: ISO standard 20579‐4 N2 - The international ISO Standard 20579‐4, dealing with the history and preparation of nano‐objects for surface analysis, has been developed to help address some of the replication and reproducibility issues caused by the fundamental nature of nanoobjects. Although all types of samples requiring surface analysis need thoughtful preparation, nano‐objects, for which many properties are controlled by their surfaces, present additional challenges in order to avoid variations and artefacts due to the handling and preparation of materials prior to analysis. This international standard is part of a series of standards related to preparation of samples for surface chemical analysis. Parts 1 and 2 of ISO Standard series 20579 address general issues that apply to many samples. Part 3, which is still in development, will focus on biomaterials. Part 4 specifically considers issues that arise due to the inherent nature of nano‐objects. Because of sensitivity to their environment, the standard indicates the minimum Information that needs to be reported about the handling and preparation of nano‐objects prior to surface analysis. This information should become part of sample provenance information that helps assure the reliability and usefulness of data obtained from surface‐analysis in the context of the synthesis, processing, and analysis history of a batch of material. Application of this standard can help address reproducibility and traceability issues associated with synthesis, processing, and characterization of nano‐objects in research and commercial applications. KW - Nano‐object characterization KW - Nanoparticle characterization KW - Provenance information KW - Sample preparation KW - Surface analysis PY - 2018 DO - https://doi.org/10.1002/sia.6490 SN - 0142-2421 SN - 1096-9918 VL - 50 IS - 9 SP - 902 EP - 906 PB - John Wiley & Sons, Ltd. AN - OPUS4-45830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Beyranvand, S. A1 - Pourghobadi, Z. A1 - Sattari, S. A1 - Soleymani, K. A1 - Donskyi, Ievgen A1 - Gharabaghi, M. A1 - Unger, Wolfgang A1 - Farjanikish, G. A1 - Nayebzadeh, H. A1 - Adeli, M. T1 - Boronic acid functionalized graphene platforms for diabetic wound N2 - While noncovalent interactions between graphene derivatives and biosystems are extensively studied, less knowledge about their covalent multivalent interactions at biointerfaces is available. Due to the affinity of boronic acids towards cis-diol bearing biosystems, graphene sheets with this functionality were synthesized and their covalent interactions with the bacteria and nematode were investigated. As expected, graphene platforms with boronic acid functionality were able to wrap bacteria and destroy it in a short time. Surprisingly, body of nematodes was ruptured and their viability decreased to 30% after 24 h incubation with the functionalized graphene sheets. Because of their antibacterial and antiparasitic activities as well as their ability for wound dressing, graphene platforms with the boronic acid functionality were further investigated for diabetic wound healing. In vivo experiments showed that graphene platforms are more efficient than the commercially available drug, phenytoin, and restore both infected and non-infected diabetic wounds in ten days. Taking advantage of their straightforward synthesis, strong interactions with different biosystems as well as their ability to heal diabetic wounds, the boronic Acid functionalized graphene sheets are promising candidates for a broad range of future biomedical applications. KW - Graphene KW - Boronic acid KW - Functionalized graphene KW - XPS PY - 2020 UR - https://www.sciencedirect.com/science/article/abs/pii/S0008622319310954 DO - https://doi.org/doi.org/10.1016/j.carbon.2019.10.077 VL - 158 SP - 327 EP - 336 PB - Elsevier Ltd. AN - OPUS4-50559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cant, D. J. H. A1 - Minelli, C. A1 - Sparnacci, K. A1 - Müller, Anja A1 - Kalbe, H. A1 - Stoger-Pollach, M. A1 - Unger, Wolfgang A1 - Werner, W. S. M. A1 - Shard, A. G. T1 - Surface-Energy Control and Characterization of Nanoparticle Coatings N2 - Accurate and reproducible measurement of the structure and properties of high-value nanoparticles is extremely important for their commercialization. A significant proportion of engineered nanoparticle systems consist of some form of nominally core-shell structure, whether by design or unintentionally. Often, these do not form an ideal core-shell structure, with typical deviations including polydispersity of the core or shell, uneven or incomplete shells, noncentral cores, and others. Such systems may be created with or without intent, and in either case an understanding of the conditions for formation of such particles is desirable. Precise determination of the structure, composition, size, and shell thickness of such particles can prove challenging without the use of a suitable range of characterization techniques. Here, the authors present two such polymer core-shell nanoparticle systems, consisting of polytetrafluoroethylene cores coated with a range of thicknesses of either polymethylmethacrylate or polystyrene. By consideration of surface energy, it is shown that these particles are expected to possess distinctly differing coating structures, with the polystyrene coating being incomplete. A comprehensive characterization of these systems is demonstrated, using a selection of complementary techniques including scanning electron microscopy, scanning transmission electron microscopy, thermogravimetric analysis, dynamic light scattering, differential centrifugal sedimentation, and X-ray photoelectron spectroscopy. By combining the results provided by these techniques, it is possible to achieve superior characterization and understanding of the particle structure than could be obtained by considering results separately. KW - Nanoparticles KW - Core-shell KW - XPS KW - Size KW - Thickness KW - Damage PY - 2020 DO - https://doi.org/10.1021/acs.jpcc.0c02161 VL - 124 IS - 20 SP - 11200 EP - 11211 PB - ACS CY - Washington DC AN - OPUS4-50899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cant, D. J. H. A1 - Müller, Anja A1 - Clifford, C. A. A1 - Unger, Wolfgang A1 - Shard, A. G. T1 - Summary of ISO/TC 201 Technical Report 23173—Surface chemical analysis—Electron spectroscopies—Measurement of the thickness and composition of nanoparticle coatings N2 - ISO Technical Report 23173 describes methods by which electron spectroscopies, including X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and synchrotron techniques, can be employed to calculate the Coating thicknesses and compositions of nanoparticles. The document has been developed to review and outline the current state-of-the-art for such measurements. Such analyses of core–shell nanoparticles are common within the literature, however the methods employed are varied; the relative advantages and disadvantages of These methods, and the optimal usage of each may not be clear to the general analyst. ISO Technical Report 23173 aims to clarify the methods that are available, describe them in clear terms, exhibit examples of their use, and highlight potential issues users may face. The information provided should allow analysts of electron spectroscopy data to make clear choices regarding the appropriate analysis of electron spectroscopy data from coated nanoparticle systems and provide a basis for understanding and comparing results from different methods and systems. KW - Electron spectroscopy KW - Core-shell KW - Nanoparticles KW - ISO 23173 KW - XPS KW - Thickness KW - Composition PY - 2021 DO - https://doi.org/10.1002/sia.6987 SN - 0142-2421 VL - 53 IS - 10 SP - 893 EP - 899 PB - John Wiley & Sons Ltd AN - OPUS4-52976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Daneshnia, S. A1 - Adeli, M. A1 - Yari, A. A1 - Shams, A. A1 - Donskyi, Ievgen A1 - Unger, Wolfgang T1 - Low temperature functionalization of two-dimensional boron nitride for electrochemical sensing N2 - Two-dimensional hexagonal boron nitride(h-BN)as an emerging nanomaterial exhibits uniquephysicochemical properties, making it suitable candidate for a wide spectrum of applications.However, due to its poor functionality, the processability of this nanomaterial is low. In this work, wereport on a straightforward and scalable approach for the functionalization of h-BN by nitrene[2+1]cycloaddition at room temperature. The triazine-functionalized h-BN(Trz-BNs)showed ahigh reactivity toward nucleophiles, through which post-modifications are performable. The post-modification of Trz-BNs by L-cysteine was studied using cyclic voltammetry and differential pulsevoltammetry. Taking advantage of the scalable and straightforward functionalization as well as abilityof triazine functional groups for the controlled post-modifications, Trz-BNs is a promisingnanoplatform for a wide range of future applications. KW - Two-dimensional hexagonal boron nitride(h-BN) KW - Nitrene[2+1]cycloaddition KW - Post-modification by L-cysteine KW - Electrochemical sensing KW - XPS PY - 2019 DO - https://doi.org/10.1088/2053-1591/ab317b SN - 2053-1591 VL - 6 IS - 9 SP - 095076, 1 EP - 11 PB - IOP Publishing Ltd AN - OPUS4-48635 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, P. M. A1 - Kjærvik, Marit A1 - Willneff, E. A. A1 - Unger, Wolfgang T1 - In-depth analysis of iodine in artificial biofilm model layers by variable excitation energy XPS and argon gas cluster ion sputtering XPS N2 - Here, we present a study on agarose thin-film samples that represent a model system for the exopolysaccharide matrix of biofilms. Povidone-iodide (PVP-I) was selected as an antibacterial agent to evaluate our x-ray photoelectron spectroscopy (XPS)-based methodology to trace specific marker elements, here iodine, commonly found in organic matrices of antibiotics. The in-depth distribution of iodine was determined by XPS analyses with variable excitation energies and in combination with argon gas cluster ion beam sputter cycles. On mixed agarose/PVP-I nanometer-thin films, both methods were found to solve the analytical task and deliver independently comparable results. In the mixed agarose/PVP-I thin film, we found the outermost surface layer depleted in iodine, whereas the iodine is homogeneously distributed in the depth region between this outermost surface layer and the interface between the thin film and the substrate. Depletion of iodine from the uppermost surface in the thin-film samples is assumed to be caused by ultrahigh vacuum exposure resulting in a loss of molecular iodine (I2) as reported earlier for other iodine-doped polymers. KW - Biofilm KW - XPS KW - Argon gas cluster ion sputtering KW - Variable excitation KW - Iodine PY - 2022 DO - https://doi.org/10.1116/6.0001812 SN - 1934-8630 VL - 17 IS - 3 SP - 1 EP - 8 PB - AVS AN - OPUS4-54973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul M. A1 - Lange, Nele A1 - Lippitz, Andreas A1 - Holzweber, Markus A1 - Kulak, N. A1 - Unger, Wolfgang T1 - Click chemistry on silicon nitride for biosensor fabrication N2 - Biosensors are of essential importance in medical and biological diagnostics. Often, they are produced using silane chemistry on glass or silicon oxide surfaces. However, controlling that silane chemistry is challenging. Here, we present an alternative strategy to form functional organic layers and biosensors on silicon Nitride (Si3N4). H-terminated Si3N4 films are used to generate reactive azide groups by various azidation methods. Biomolecular probes can then be immobilized using click chemistry reactions with the azide groups and due to its high sensitivity in XPS a fluorine-substituted test alkyne was utilized to optimize click chemistry conditions. After that a biotinylated alkyne was clicked to Si3N4 surfaces followed by immobilization of streptavidin as analyte in a model assay. The functionalized surfaces were thoroughly characterized by surface chemical analysis using X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS)spectroscopy. KW - Biosensors KW - H-terminated Si3N4 films KW - Click chemistry KW - X-ray photoelectron spectroscopy KW - Near edge X-ray absorption fine structure KW - Streptavidin binding PY - 2019 DO - https://doi.org/10.1016/j.apsusc.2019.03.002 SN - 0169-4332 VL - 481 SP - 10 EP - 15 PB - Elsevier B.V. AN - OPUS4-48634 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Unger, Wolfgang T1 - Summary of ISO/TC 201 technical report: ISO/TR 19693 surface chemical analysis—characterization of functional glass substrates for biosensing applications N2 - ISO/TR 19693:2018—Surface chemical analysis—Characterization of functional glass substrates for biosensing applications gives an overview of methods, strategies, and guidance to identify possible sources of problems related to substrates, device production steps (cleaning, activation, and chemical modification), and shelf life (storage conditions and aging). It is particularly relevant for surface chemical analysts characterizing glass‐based biosensors, and developers or quality managers in the biosensing device production community. Based on quantitative and qualitative surface chemical analysis, strategies for identifying the cause of poor Performance during device manufacturing can be developed and implemented. A review of measurement capabilities of surface analytical methods is given to assist readers from the biosensing community. KW - Bio sensing device KW - Surface chemical analysis KW - XPS KW - SIMS KW - Standardization PY - 2018 DO - https://doi.org/10.1002/sia.6481 SN - 0142-2421 SN - 1096-9918 VL - 50 IS - 8 SP - 835 EP - 838 PB - John Wiley & Sons, Ltd. AN - OPUS4-45829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Azab, W. A1 - Cuellar-Camach, J.L. A1 - Guday, G. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Osterrieder, K. A1 - Adeli, M. A1 - Haag, R. T1 - Functionalized nanographene sheets with high antiviral activity through synergistic electrostatic and hydrophobic interactions N2 - As resistance to traditional drugs emerges for treatment of Virus infections, the need for new methods for virus inhibition increases. Graphene derivatives with large surface areas have shown strong activity against different viruses. However, the inability of current synthetic protocols to accurately manipulate the structure of graphene sheets in order to control their antiviral activity remains a major challenge. In this work, a series of graphene derivatives with defined polyglycerol sulfate and fatty amine functionalities have been synthesized and their interactions with herpes simplex Virus type 1 (HSV-1) are investigated. While electrostatic interactions between polyglycerol sulfate and virus particles trigger the binding of graphene to virus, alkyl chains induce a high antiviral activity by secondary hydrophobic interactions. Among graphene sheets with a broad range of alkyl chains, (C3–C18), the C12-functionalized sheets showed the highest antiviral activity, indicating the optimum synergistic effect between electrostatic and hydrophobic interactions, but this derivative was toxic against the Vero cell line. In contrast, sheets functionalized with C6- and C9-alkyl chains showed low toxicity against Vero cells and a synergistic Inhibition of HSV-1. This study shows that antiviral agents against HSV-1 can be obtained by controlled and stepwise functionalization of graphene sheets and may be developed into antiviral agents for future biomedical applications. KW - Functionalized nanographene KW - X-ray Photoelectron Spectroscopy (XPS) KW - NEXAFS KW - Antiviral activity PY - 2019 DO - https://doi.org/10.1039/c9nr05273a SN - 2040-3364 VL - 11 IS - 34 SP - 15804 EP - 15809 PB - The Royal Society of Chemistry AN - OPUS4-48807 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Chen, Y. A1 - Nickl, Philip A1 - Guday, G. A1 - Qiao, H. A1 - Achasi, K. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Böttcher, C. A1 - Chen, W. A1 - Adeli, M. A1 - Haag, R. T1 - Self-degrading graphene sheets for tumor therapy N2 - Low biodegradability of graphene derivatives and related health risks are the main limiting factors for their in vivo biomedical applications. Here, we present the synthesis of enzyme-functionalized graphene sheets with self-degrading properties under physiological conditions and their applications in Tumor therapy. The synergistic enzyme cascade glucose oxidase and myeloperoxidase are covalently conjugated to the surface of graphene sheets and two-dimensional (2D) platforms are obtained that can produce sodium hypochlorite from glucose. The enzyme-functionalized graphene sheets with up to 289 nm average size are degraded into small pieces (≤40 nm) by incubation under physiological conditions for 24 h. Biodegradable graphene sheets are further loaded with doxorubicin and their ability for Tumor therapy is evaluated in vitro and in vivo. The laser-triggered release of doxorubicin in combination with the enzymatic activity of the functionalized graphene sheets results in a synergistic antitumor activity. Taking advantage of their neutrophil-like activity, fast biodegradability, high photo- and chemotherapeutic effects, the novel two-dimensional nanoplatforms can be used for tumor therapeutic applications. KW - Graphene KW - Self-degrading KW - Thumor therapy KW - XPS KW - NEXAFS PY - 2020 DO - https://doi.org/10.1039/d0nr02159h SP - 1 EP - 12 PB - The Royal Society of Chemistry AN - OPUS4-50978 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Drüke, M. A1 - Silberreis, K. A1 - Lauster, D. A1 - Ludwig, K. A1 - Kühne, C. A1 - Unger, Wolfgang A1 - Böttcher, C. A1 - Herrmann, A. A1 - Dernedde, J. A1 - Adeli, M. A1 - Haag, R. T1 - Interactions of fullerene-polyglycerol sulfates at viral and cellular interfaces N2 - Understanding the mechanism of interactions of nanomaterials at biointerfaces is a crucial issue to develop new antimicrobial vectors. In this work, a series of water-soluble fullerene-polyglycerol sulfates (FPS) with different fullerene/polymer weight ratios and varying numbers of polyglycerol sulfate branches are synthesized, characterized, and their interactions with two distinct surfaces displaying proteins involved in target cell recognition are investigated. The combination of polyanionic branches with a solvent exposed variable hydrophobic core in FPS proves to be superior to analogs possessing only one of these features in preventing interaction of vesicular Stomatitis virus coat glycoprotein (VSV-G) with baby hamster kidney cells serving as a model of host cell. Interference with L-selectin-ligand binding is dominated by the negative charge, which is studied by two assays: a competitive surface plasmon resonance (SPR)-based inhibition assay and the leukocyte cell (NALM-6) rolling on ligands under flow conditions. Due to possible intrinsic hydrophobic and electrostatic effects of synthesized compounds, pico- to nanomolar half maximal inhibitory concentrations (IC50) are achieved. With their highly antiviral and anti-inflammatory properties, together with good biocompatibility, FPS are promising candidates for the future development towards biomedical applications. KW - Fullerene-Polyglycerol Sulfates KW - Fullerene KW - Biointerfaces KW - XPS PY - 2018 DO - https://doi.org/10.1002/smll.201800189 SN - 1613-6829 SN - 1613-6810 VL - 14 IS - 17 SP - 1800189, 1 EP - 7 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-44573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Faghani, A. A1 - Gholami, M. F. A1 - Trunk, M. A1 - Müller, J. A1 - Pachfule, P. A1 - Vogl, S. A1 - Donskyi, Ievgen A1 - Li, M. A1 - Nickl, Philip A1 - Shao, J. A1 - Huang, M. R. S. A1 - Unger, Wolfgang A1 - Arenal, R. A1 - Koch, C. T. A1 - Paulus, B. A1 - Rabe, J. P. A1 - Thomas, A. A1 - Haag, R. A1 - Adeli, M. T1 - Metal-Assisted and Solvent-Mediated Synthesis of Two-Dimensional Triazine Structures on Gram Scale N2 - Covalent triazine frameworks are an emerging material class that have shown promising performance for a range of applications. In this work, we report on a metal-assisted and solvent-mediated reaction between calcium carbide and cyanuric chloride, as cheap and commercially available precursors, to synthesize two-dimensional triazine structures (2DTSs). The reaction between the solvent, dimethylformamide, and cyanuric chloride was promoted by calcium carbide and resulted in dimethylamino-s-triazine intermediates, which in turn undergo nucleophilic substitutions. This reaction was directed into two dimensions by calcium ions derived from calcium carbide and induced the formation of 2DTSs. The role of calcium ions to direct the two-dimensionality of the final structure was simulated using DFT and further proven by synthesizing molecular intermediates. The water content of the reaction medium was found to be a crucial factor that affected the structure of the products dramatically. While 2DTSs were obtained under anhydrous conditions, a mixture of graphitic material/2DTSs or only graphitic material (GM) was obtained in aqueous solutions. Due to the straightforward and gram-scale synthesis of 2DTSs, as well as their photothermal and photodynamic properties, they are promising materials for a wide range of future applications, including bacteria and virus incapacitation. KW - XPS KW - Triazine KW - 2D PY - 2020 DO - https://doi.org/10.1021/jacs.0c02399 VL - 142 IS - 30 SP - 12976 EP - 12986 PB - ACS American Chemical Society AN - OPUS4-51203 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guday, G. A1 - Donskyi, Ievgen A1 - Gholami, M. F. A1 - Algara-Siller, G. A1 - Witte, F. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Paulus, B. A1 - Rabe, J. A1 - Adeli, M. A1 - Haag, R. T1 - Scalable Production of Nanographene and Doping via Nondestructive Covalent Functionalization N2 - A new method for top‐down, one‐pot, gram‐scale production of high quality nanographene by incubating graphite in a dilute sodium hypochlorite solution at only 40 °C is reported here. The produced sheets have only 4 at% oxygen content, comparable with nanographene grown by chemical vapor deposition. The nanographene sheets are covalently functionalized using a nondestructive nitrene [2+1] cycloaddition reaction that preserves their π‐conjugated system. Statistical analyses of Raman spectroscopy and X‐ray photoelectron spectroscopy indicate a low number of sp3 carbon atoms on the order of 2% before and 4% after covalent functionalization. The nanographene sheets are significantly more conductive than conventionally prepared nanographene oxide, and conductivity further increases after covalent functionalization. The observed doping effects and theoretical studies suggest sp2 hybridization for the carbon atoms involved in the [2+1] cycloaddition reaction leading to preservation of the π‐conjugated system and enhancing conductivity via n‐type doping through the bridging N‐atom. These methods are easily scalable, which opens the door to a mild and efficient process to produce high quality nanographenes and covalently functionalize them while retaining or improving their physicochemical properties. KW - Graphene KW - XPS KW - NEXAFS PY - 2019 DO - https://doi.org/10.1002/smll.201805430 VL - 15 IS - 12 SP - 1805430 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-48021 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinen, S. A1 - Rackow, S. A1 - Cuellar-Camacho, J. L. A1 - Donskyi, Ievgen A1 - Unger, Wolfgang A1 - Weinhart, M. T1 - Transfer of functional thermoresponsive poly(glycidyl ether) coatings for cell sheet fabrication from gold to glass surfaces N2 - Thermoresponsive polymer coatings can facilitate cell sheet fabrication under mild conditions by promoting cell adhesion and proliferation at 37 1C. At lower temperatures the detachment of confluent cell sheets is triggered without enzymatic treatment. Thus, confluent cell sheets with intact extracellular matrix for regenerative medicine or tissue engineering applications become available. Herein, we applied the previously identified structural design parameters of functional, thermoresponsive poly(glycidyl ether) brushes on gold to the more application-relevant substrate glass via the self-assembly of a corresponding block copolymer (PGE-AA) with a short surface-reactive, amine-presenting anchor block. Both, physical and covalent immobilization on glass via either multivalent ionic interactions of the anchor block with bare glass or the coupling of the anchor block to a polydopamine (PDA) adhesion layer on glass resulted in stable coatings. Atomic force microscopy revealed a high degree of roughness of covalently attached coatings on the PDA adhesion layer, while physically attached coatings on bare glass were smooth and in the brush-like regime. Cell sheets of primary human dermal fibroblasts detached reliably (86%) and within 20 ± 10 min from physically tethered PGE-AA coatings on glass when prepared under cloud point grafting conditions. The presence of the laterally inhomogeneous PDA adhesion layer, however, hindered the spontaneous temperature-triggered cell detachment from covalently grafted PGE-AA, decreasing both detachment rate and reliability. Despite being only physically attached, self-assembled monolayer brushes of PGE-AA block copolymers on glass are functional and stable thermoresponsive coatings for application in cell sheet fabrication of human fibroblasts as determined by X-ray photoelectron spectroscopy. KW - X-ray photoelectron spectroscopy KW - Thermoresponsive poly(glycidyl ether) coatings KW - Cell sheet fabrication KW - Nm film thickness PY - 2018 DO - https://doi.org/10.1039/c7tb03263c SN - 2050-750X SN - 2050-7518 VL - 6 IS - 10 SP - 1489 EP - 1500 PB - The Royal Society of Chemistry AN - OPUS4-44600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinrich, Thomas A1 - Darlatt, Erik A1 - Lippitz, Andreas A1 - Müller, S. A1 - Schalley, C. A1 - Unger, Wolfgang T1 - Systematic XP and NEXAFS spectroscopy studies of (ter-)pyridineterminated self-assembled monolayers and their addressability for functional molecules N2 - The chemical composition of surfaces functionalized with self-assembled monolayers (SAMs) is an important parameter that determines their performance in a broad range of applications, from immobilizing molecular machines to initiation and growth control of MOFs (Metal-Organic Frameworks). In this article, a critical Survey of XPS (X-ray photoelectron spectroscopy) and NEXAFS (near edge X-ray absorption fine structure) spectroscopy data for pyridine-functionalized monolayers on gold surfaces is presented to compile correlations that have been indiscernible before. Monolayers with aromatic backbones are compared to monolayers with aliphatic backbones. Monolayers with pyridine end-groups are compared to mixed monolayers formed terpyridine-functionalized by molecules end-groups and non-functionalized molecules. Thiol-oxidation during ageing of the SAMs in air is addressed. And finally, the addressability of the SAMs for the deposition of metal-ions and organic molecules is investigated and compared. This work consequently delivers a comprehensive set of spectroscopic data of (ter-)pyridine-terminated SAMs and their performance as template for the preparation of functional multilayers of macrocycles exhibiting a preferential orientation. KW - (ter-)pyridineterminated self-assembled monolayer KW - X-ray Photoelectron Spectroscopy (XPS) KW - NEXAFS PY - 2019 DO - https://doi.org/10.1016/j.elspec.2019.03.011 VL - 233 SP - 28 EP - 37 PB - Elsevier B.V. AN - OPUS4-48018 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holzweber, Markus A1 - Lippitz, Andreas A1 - Hesse, R. A1 - Denecke, R. A1 - Werner, W. A1 - Unger, Wolfgang T1 - The use of ionic liquids for the determination of the spectrometer transmission function in X-ray photoelectron spectroscopy (XPS) N2 - The uncertainty of measurement in quantitative XPS analysis can be reduced by using a calibrated spectrometer transmission function T (E), which is usually determined by taking spectra from Au, Ag, Cu and Ge elemental reference materials. However, this approach is quite time-consuming due to required sample preparation steps like sputter cleaning etc., and the relatively big number of samples to be measured. This contribution proposes the use of the ionic liquids [C2C1im][NTf2] and [C3C1im][NTf2] as reference materials for a determination of T(E). These multi-elemental samples deliver five intensive photoemission peaks, F 1s, O 1s, N 1s, C 1s and S 2p, in an energy window from 160 eV to 700 eV which is of specific interest for applications of quantitative XPS for surface chemical analysis of soft matter, one of the major applications of XPS. KW - Quantitative XPS KW - Ionic liquid KW - Transmission function PY - 2019 DO - https://doi.org/10.1016/j.elspec.2019.03.008 VL - 233 SP - 51 EP - 56 PB - Elsevier B.V. AN - OPUS4-48019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kim, K.J. A1 - Kim, C.S. A1 - Ruh, S. W. A1 - Unger, Wolfgang A1 - Radnik, Jörg A1 - Mata-Salazar, J. A1 - Juarez-Garcia, J.M. A1 - Cortazar-Martinez, O. A1 - Herrera-Gomez, A. A1 - Hansen, P.E. A1 - Madesen, J.S. A1 - Senna, C.A. A1 - Archanjo, B.S. A1 - Damasceno, J.C. A1 - Achete, C.A. A1 - Wang, H. A1 - Wang, M. A1 - Windover, D. A1 - Steel, E. A1 - Kurokawa, A. A1 - Fujimoto, T. A1 - Azuma, Y. A1 - Terauchi, S. A1 - Zhang, L. A1 - Jordaan, W.A. A1 - Spencer, S.J. A1 - Shard, A.G. A1 - Koenders, L. A1 - Krumrey, M. A1 - Busch, I. A1 - Jeynes, C. T1 - Thickness measurement of nm HfO2 films N2 - A pilot study for the thickness measurement of HfO2 films was performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of this pilot study was to ensure the equivalency in the measurement capability of national metrology institutes for the thickness measurement of HfO2 films. In this pilot study, the thicknesses of six HfO2 films with nominal thickness from 1 nm to 4 nm were measured by X-ray Photoelectron Spectroscopy (XPS), X-ray Reflectometry(XRR), X-ray Fluorescence Analysis (XRF), Transmission Electron Spectroscopy (TEM), Spectroscopic Ellipsometry (SE) and Rutherford Backscattering Spectrometry (RBS). The reference thicknesses were determined by mutual calibration of a zero-offset method (Medium Energy Ion Scattering Spectroscopy (MEIS) of KRISS) and a method traceable to the length unit (the average thicknesses of three XRR data except the thinnest film). These reference thicknesses are traceable to the length unit because they are based on the traceability of XRR. For the thickness measurement by XPS, the effective attenuation length of Hf 4f electrons was determined. In the cases of XRR and TEM, the offset values were determined from a linear fitting between the reference thicknesses and the individual data by XRR and TEM. The amount of substance of HfO2, expressed as thickness of HfO2 films (in both linear and areal density units), was found to be a good subject for a CCQM key comparison. To reach the main text of this paper, click on Final Report. The final report has been peer-reviewed and approved for publication by the CCQM. KW - Thickness measurements KW - nm films KW - X-ray Photoelectron Spectroscopy KW - Mutual calibration PY - 2021 DO - https://doi.org/10.1088/0026-1394/58/1A/08016 SN - 0026-1394 VL - 58 IS - 1a SP - 08016 PB - IOP Publishing Lt. CY - Bristol AN - OPUS4-54175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Dietrich, P. M. A1 - Thissen, A. A1 - Radnik, Jörg A1 - Nefedov, A. A1 - Natzeck, C. A1 - Wöll, C. A1 - Unger, Wolfgang T1 - Application of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) in an in-situ analysis of the stability of the surface-supported metal-organic framework HKUST-1 in water, methanol and pyridine atmospheres N2 - Surface-supported metal-organic frameworks HKUST-1 (Hong Kong University of Science and Technology) were used as a model system for a development of a near ambient pressure (NAP) XPS based approach to investigate interaction with atmospheres of water, methanol or pyridine at pressures ranging from 1 to 4 mbar. The films were grown on a gold substrate functionalized with a COOH-terminated self-assembled monolayer using liquidphase epitaxy in a step-by-step fashion. Measurement protocols were developed and optimised for different gases in order to obtain spectra of similar quality in terms of signal intensity, noise and shape. Peak shapes were found to depend on the efficiency of charge compensation. Reference measurements in argon proved to be a useful strategy not only for the evaluation of the Cu(II)-fraction in pristine samples, but also to identify the contributions by the respective gas atmosphere to the C 1s and O 1s photoelectron spectra. Reduced copper was found during the exposition of HKUST-1 to water vapour and pyridine, but this effect was not observed in case of methanol. Additionally, it was established that there are no changes in relative Cu(II) percentage with increasing exposure time. This indicates that saturation was reached already at the lowest time of gas exposure. A detailed elucidation of the mechanism of Cu(II) reduction to Cu(I) in HKUST-1 mediated by water and pyridine is part of ongoing work and not in the scope of the present paper. KW - HKUST-1 KW - Near-ambient pressure X-ray photoelectron spectroscopy KW - Metal-organic frameworks KW - Interaction with atmospheres KW - Water PY - 2021 DO - https://doi.org/10.1016/j.elspec.2020.147042 SN - 0368-2048 IS - 247 SP - 147042 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-52098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -