We previously screened a whole-cell lipase EC 3.1.1.3 from the novel strain Aspergillus niger GZUF36, which exhibited 1,3-selectivity in the synthesis of 1,3-diacylglycerol via glycerolysis. However, the mechanism of lipase selectively in catalyzing the sn-1,3 position remains ambiguous. This work was performed to investigate the 1,3-selective mechanism of lipase using glycerolysis to synthesize 1,3-diacylglycerol (1,3-DG) as a model reaction by changing solvent(s) and water activity (a), and addition of salt hydrate pair. The measured diacylglycerol yield was also used to examine lipase activity. Results indicated that not only organic solvent and a have strong effect on the sn-1,3 selectivity, but also ions of salt hydrate pair also affected selectivity. Lipase conformation was altered by hydrophobic interactions of the solvent, a, or ions of salt hydrate, resulting in distinct sn-1,3 selectivity of the lipase. The salt hydrate pair changed the lipase conformation and selectivity not only by a but also by static interactions, which was rarely reported. These parameters also affected lipase activity. The lipase displayed the highest selectivity (about 88%) and activity in solvents of t-butanol and n-hexane (1:29, v/v) at a 0.43. The results demonstrated that the sn-1,3 selectivity and activity of the lipase from A. niger GZUF36 may be improved by control of some crucial factors. This work laid a foundation for the application of lipase in the synthesis of 1,3-DG and other structural and functional lipids.

A facile and simple one-step solvothermal method has been developed to synthesize polyethyleneimine (PEI)-modified magnetic nanoparticles. Characterization of morphology, surface charges, crystal structure, and magnetic property confirmed the efficiency of this facile synthesis route. Lipase immobilized on the PEI-modified magnetic nanoparticles was used to synthesize vitamin A palmitate from vitamin A acetate and palmitic acid. The reuse of immobilized lipase can be extended to eight times by removing water during esterification with a conversion rate above 80 % for 12 h.

The concept of complementary resistive switching (CRS) has been proposed as a potential solution for mitigating the unwanted sneak path current intrinsic to large-scale crossbar memory arrays. In this study, CRS devices based on egg albumen are fabricated using non-inert Al layers as the top electrodes (TE). The Al/Albumen/indium tin oxide (ITO) single sandwich structure achieves stable and reproducible CRS behavior without requiring a forming process. The application of a compliance current leads to an evolution from CRS to bipolar resistive switching (BRS). Furthermore, the BRS analog switching feature enables the emulation of synaptic functions, like paired-pulse facilitation (PPF) and paired-pulse depression (PPD). Our systematic and in-depth analyses demonstrate that the CRS is due to the interfacial Schottky barriers originating from the Al electrode oxidation. Consequently, the resistance switching behavior in the albumen-based cells with inert Pt top electrodes can further validate this model. These findings provide significant insight into the role of non-inert electrodes and contribute to a comprehensive understanding of the CRS mechanism, which may facilitate the development of high-performance CRS biodevices.