-
Nano-micro Letters Jul 2023Precisely tuning the spacing of the active centers on the atomic scale is of great significance to improve the catalytic activity and deepen the understanding of the...
Precisely tuning the spacing of the active centers on the atomic scale is of great significance to improve the catalytic activity and deepen the understanding of the catalytic mechanism, but still remains a challenge. Here, we develop a strategy to dilute catalytically active metal interatomic spacing (d) with light atoms and discover the unusual adsorption patterns. For example, by elevating the content of boron as interstitial atoms, the atomic spacing of osmium (d) gradually increases from 2.73 to 2.96 Å. More importantly, we find that, with the increase in d, the hydrogen adsorption-distance relationship is reversed via downshifting d-band states, which breaks the traditional cognition, thereby optimizing the H adsorption and HO dissociation on the electrode surface during the catalytic process; this finally leads to a nearly linear increase in hydrogen evolution reaction activity. Namely, the maximum d of 2.96 Å presents the optimal HER activity (8 mV @ 10 mA cm) in alkaline media as well as suppressed O adsorption and thus promoted stability. It is believed that this novel atomic-level distance modulation strategy of catalytic sites and the reversed hydrogen adsorption-distance relationship can shew new insights for optimal design of highly efficient catalysts.
PubMed: 37395826
DOI: 10.1007/s40820-023-01142-1 -
Bioelectrochemistry (Amsterdam,... Oct 2023We investigated the bioelectrochemical properties of an FAD-dependent glucose dehydrogenase from Trichoderma virens (TvGDH) and its electrochemical behaviour when...
We investigated the bioelectrochemical properties of an FAD-dependent glucose dehydrogenase from Trichoderma virens (TvGDH) and its electrochemical behaviour when immobilized on a graphite electrode. TvGDH was recently shown to have an unusual substrate spectrum and to prefer maltose over glucose as substrate, and hence could be of interest as recognition element in a maltose sensor. In this study, we determined the redox potential of TvGDH, which is -0.268 ± 0.007 V vs. SHE, and advantageously low to be used with many redox mediators or redox polymers. The enzyme was entrapped in, and wired by an osmium redox polymer (poly(1-vinylimidazole-co-allylamine)-{[Os(2,2'-bipyridine)Cl]Cl}) with formal redox potential of +0.275 V vs. Ag|AgCl via poly(ethylene glycol) diglycidyl ether crosslinking onto a graphite electrode. When the TvGDH-based biosensor was tested with maltose it showed a sensitivity of 1.7 μA mMcm, a linear range of 0.5-15 mM, and a detection limit of 0.45 mM. Furthermore, it gave the lowest apparent Michaelis-Menten constant (K) of 19.2 ± 1.5 mM towards maltose when compared to other sugars. The biosensor is also able to detect other saccharides including glucose, maltotriose and galactose, these however also interfere with maltose sensing.
Topics: Glucose 1-Dehydrogenase; Hypocrea; Graphite; Maltose; Glucose; Biosensing Techniques; Electrodes; Oxidation-Reduction; Polymers; Enzymes, Immobilized
PubMed: 37269684
DOI: 10.1016/j.bioelechem.2023.108480 -
Microscopy (Oxford, England) Nov 2023Biological nanoparticles, such as bacterial outer membrane vesicles (OMVs), are routinely characterized through transmission electron microscopy (TEM). In this study, we...
Biological nanoparticles, such as bacterial outer membrane vesicles (OMVs), are routinely characterized through transmission electron microscopy (TEM). In this study, we report a novel method to prepare OMVs for TEM imaging. To preserve vesicular shape and structure, we developed a dual fixation protocol involving osmium tetroxide incubation prior to negative staining with uranyl acetate. Combining osmium tetroxide with uranyl acetate resulted in preservation of sub-50 nm vesicles and improved morphological stability, enhancing characterization of lipid-based nanoparticles by TEM.
Topics: Microscopy, Electron; Coloring Agents; Osmium Tetroxide; Bacterial Outer Membrane; Microscopy, Electron, Transmission; Staining and Labeling; Osmium
PubMed: 37148329
DOI: 10.1093/jmicro/dfad027