@misc{JurischkaDinterEfimovaetal., author = {Jurischka, Christoph and Dinter, Franziska and Efimova, Anastasia and Weiss, Romano and Schiebel, Juliane and Schulz, Christian and Fayziev, Bekzodjon and Schierack, Peter and Fischer, Thomas and R{\"o}diger, Stefan}, title = {An explorative study of polymers for 3D printing of bioanalytical test systems}, series = {Clinical Hemorheology and Microcirculation}, volume = {75}, journal = {Clinical Hemorheology and Microcirculation}, number = {1}, issn = {1875-8622}, doi = {10.3233/CH-190713}, pages = {57 -- 84}, abstract = {Background: The 3D printing is relevant as a manufacturing technology of functional models for forensic, pharmaceutical and bioanalytical applications such as drug delivery systems, sample preparation and point-of-care tests. Objective: Melting behavior and autofluorescence of materials are decisive for optimal printing and applicability of the product which are influenced by varying unknown additives. Methods: We have produced devices for bioanalytical applications from commercially available thermoplastic polymers using a melt-layer process. We characterized them by differential scanning calorimetry, fluorescence spectroscopy and functional assays (DNA capture assay, model for cell adhesion, bacterial adhesion and biofilm formation test). Results: From 14 tested colored, transparent and black materials we found only deep black acrylonitrile-butadiene-styrene (ABS) and some black polylactic acid (PLA) useable for fluorescence-based assays, with low autofluorescence only in the short-wave range of 300-400 nm. PLA was suitable for standard bioanalytical purposes due to a glass transition temperature of approximately 60°C, resistance to common laboratory chemicals and easy print processing. For temperature-critical methods, such as hybridization reactions up to 90°C, ABS was better suited. Conclusions: Autofluorescence was not a disadvantage per se but can also be used as a reference signal in assays. The rapid development of individual protocols for sample processing and analysis required the availability of a material with consistent quality over time. For fluorescence-based assays, the use of commercial standard materials did not seem to meet this requirement.}, language = {en} } @misc{GaraiBonEfimovaetal., author = {Garai, Bikash and Bon, Volodymyr and Efimova, Anastasia and Gerlach, Martin and Senkovska, Irena and Kaskel, Stefan}, title = {Reversible switching between positive and negative thermal expansion in a metal-organic framework DUT-49}, series = {Journal of Materials Chemistry A}, volume = {39}, journal = {Journal of Materials Chemistry A}, number = {8}, issn = {2050-7496}, doi = {10.1039/D0TA06830F}, pages = {20420 -- 20428}, abstract = {Three-dimensional architectures constructed via coordination of organic ligands to metal ions (broadly termed metal-organic frameworks, MOFs), are highly interesting for many demanding applications such as gas adsorption, molecular separation, heterogeneous catalysis, molecular sensing, etc. Being constructed from heterogeneous components, such framework solids show characteristic features from both the individual components and framework-specific features. One such interesting physicochemical property is thermal expansion, which arises from thermal vibration from the organic linker and metal ions. Herein, we show a very unique example of thermal responsiveness for the DUT-49 framework, a MOF well-known for its distinctive negative gas adsorption (NGA) properties. In the guest-free form, the framework shows another counter-intuitive phenomenon of negative thermal expansion (NTE), i.e. the lattice size increases with decrease of temperature. However, in the solvated state, it shows both NTE and positive thermal expansion (i.e. lattice size decreases with lowering of temperature, PTE) based on a specific temperature range. When the solvent exists in the liquid form inside the MOF pore, it retains the pristine NTE nature of the bare framework. But freezing of the solvent inside the pores induces the strain, which causes a structural transformation through in-plane bending of the linker and this squeezes the framework by ∼10\% of the unit cell volume. This effect has been verified using 3 different solvents where the structural contraction occurs immediately at the freezing point of the individual solvent. Furthermore, studies on a series of DUT-49(M) frameworks with varying metals confirm the general applicability of this mechanism.}, language = {en} } @misc{KnorrSchmidt, author = {Knorr, Monika and Schmidt, Peer}, title = {Reactivity of ionic liquids: Reductive effect of [C4C1im]BF4 to form particles of red amorphous selenium and Bi2Se3 from oxide precursors}, series = {ChemistryOpen}, volume = {10}, journal = {ChemistryOpen}, number = {2}, issn = {2191-1363}, doi = {10.1002/open.202000264}, pages = {125 -- 140}, abstract = {Temperature-induced change in reactivity of the frequently used ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([C4C1im]BF4) is presented as a prerequisite for the rational screening of reaction courses in material synthesis. [C4C1im]BF4 becomes active with oxidic precursor compounds in reduction reaction at ϑ > 200°C, even without the addition of an external reducing agent. The reaction mechanism of forming red amorphous selenium from SeO2 is investigated as a model system and can be described similarly to the Riley oxidation. The reactive species but-1-ene, which is formed during the decomposition of [C4C1im]BF4, reacts with SeO2 and form but-3-en-2-one, water, and selenium. Elucidation of the mechanism was achieved by thermoanalytical investigations. The mono-tropic phase transition of selenium was analyzed by the differential scanning calorimetry. Beyond, the suitability of the single source oxide precursor Bi2Se3O9 for the synthesis of Bi2Se3 particles was confirmed. Identification, characterization of formed solids succeeded by using light microscopy, XRD, SEM, and EDX.}, language = {en} }