Sergey Beloshapkin

Ultra-thin spin coated crosslinkable hydrogels for use in cell sheet recovery—synthesis, characterisation to application

The advantages of detaching adherent cells from thermoresponsive platforms over conventional cell detachment protocols has been well documented. This study focuses on the development of an alternative method to produce thermoresponsive surfaces for cell and cell sheet regeneration to already established techniques which are complex and expensive and may be inaccessible to many laboratories. A photcrosslinkable poly-N-isopropylacrylamide (pNIPAm) copolymer was synthesised and thin films of the copolymer were deposited using the operationally simple spin coating technique which were subsequently crosslinked upon exposure to ultraviolet (UV) irradiation. Characterisation of hydrogel properties and behaviour was achieved using UV spectroscopy, atomic force microscopy (AFM), advancing contact angle, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and white light interferometry analyses. Results indicate that 3T3 fibroblast cells adhere and proliferate to confluence on hydrogels of 30 nm was comparatively poor. Confluent cell sheets were harvested from the sub 30 nm ultra-thin hydrogels upon temperature reduction within 10 min. Spin coating allows for the facile control of film thickness via variation of the depositing polymer solution concentration and therefore the routine fabrication of ultra-thin hydrogels capable of hosting cells to confluence is easily achievable.

Factors Influencing the Performance of Pd/C Catalysts in the Green Production of Hydrogen from Formic Acid.

Formic acid derived from biomass is known to be used for hydrogen production over Pd catalysts. The effects of preparation variables, structure of the carbon support, surface functional composition on the state of Pd, and catalytic properties of the samples in the vapor-phase decomposition of formic acid were studied. In all catalysts derived from Pd acetate, metal particles visible by conventional TEM had similar sizes, but the adsorption capacity towards CO responded strongly to N-doping of the carbon surface. Moreover, a decrease in the CO/Pd values was accompanied by a significant increase in the reaction rate. Taking account of X-ray photoelectron spectroscopy (XPS) and atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF/STEM) data, the trends observed were assigned to a larger fraction of single electron-deficient Pd atoms in the N-doped samples, which do not adsorb CO but interact with formic acid to produce hydrogen. This was confirmed by extended DFT studies. The obtained results are valuable for the development of Pd catalysts on carbon supports for different processes.

Support effect for nanosized Au catalysts in hydrogen production from formic acid decomposition

Catalysts with about 2.5 wt% of gold supported on Al2O3, ZrO2, CeO2, La2O3 and MgO oxides and with the same mean metal particle sizes of 2.4–3.0 nm have been studied in hydrogen production via formic acid decomposition. A strong volcano-type relation of the catalytic activity on the electronegativity of the supports cation was demonstrated with the Au/Al2O3 catalyst on the top. This indicated that the activity is affected by the acid–base properties of the support. A study of the most active Au/Al2O3 catalyst with aberration-corrected HAADF/STEM, XPS and EXAFS proved that gold is in metallic state. The content of single supported gold atoms/cations was negligible. Therefore, the mechanism of the reaction was related to the activation of formic acid on the catalysts support followed by further decomposition of the formed reaction intermediate on the Au/support interface.

Aerobic Oxidative Esterification of Benzyl Alcohol and Acetaldehyde over Gold Supported on Nanostructured Ceria–Alumina Mixed Oxides

Au nanoparticles supported on nanostructured ceria‐alumina mixed oxides (10 and 30 wt % ceria) were prepared by a deposition–precipitation method. Their properties were studied by N2 adsorption, XRD, TEM, X‐ray photoelectron spectroscopy, and UV/Vis spectroscopy under temperature‐programmed reduction or oxidation. The materials catalyzed the liquid‐phase aerobic oxidative esterification of benzyl alcohol and benzaldehyde effectively and showed a much better performance than Au supported on the individual oxides. The reactions occurred with high turnover numbers (up to 19 000) in methanol solutions in the absence of any auxiliary base and gave mainly methyl benzoate. The strong synergetic effect of ceria and alumina can be explained by the enhanced oxygen storage capacity of the materials prepared from mixed oxides compared to that of pure alumina and ceria. The order of the catalytic activity (Au/Al2O3