Screening of serine protease inhibitors with antimicrobial activity using iron oxide nanoparticles functionalized with dextran conjugated trypsin and in silico analyses of bacterial serine protease inhibition.

Plants produce a variety of proteins and peptides which are involved in their defense against pathogens. Serine protease inhibitors are a well-established class of inhibitors correlated with plant defense. Increased levels of protease inhibitors delay cell damage and expand the cell's life-span. Recently, the rapid emergence of antibiotic-resistant microbial pathogens has prompted immense interest in purifying novel antimicrobial proteins or peptides from plant sources. Usually, the purification of protease inhibitors is accomplished by salt-extraction, ultrafiltration and affinity chromatography. Here, we developed a novel approach based on iron oxide nanoparticles conjugated to dextran functionalized with trypsin beads that accelerate the quick screening and purification of antimicrobial peptides with serine protease inhibitor activity. The method described here also works for screening other inhibitors using particular protein kinases, and it is therefore a novel tool for use as the leading method in the development of novel antimicrobial agents with protease inhibitory activity. Finally, and no less important, molecular modelling and dynamics studies of a homologous inhibitor studied here with Escherichia coli trypsin and chymotrypsin are provided in order to shed some light on inhibitor-enzyme interactions.

High performance of catalytic sheet filters of V2O5-WO3/TiO2 for NOx reduction.

Nitrogen oxide (NOx) emissions in fuel from the stationary as well as from mobile sources primarily from power stations, industrial heaters, cogeneration plants, and diesel engines represent a major worldwide environmental problem. The selective catalytic reduction (SCR) of NOx with NH3 over catalyst based on V2O5-WO3/TiO2 (VWT) is the most effective benchmark technique to efficiently reduce NOx emissions from stationary and mobile sources. Among the different transition metals (Mn, Nb, Co, Cr, Cu, Ce) used in current research work, the manganese could make up the loss of SCR activity caused by the decrease of V2O5 loading (50%) in prepared VWT powder catalyst. The optimal loading of Mn is 3 wt% in case of 3V9WT powder catalyst, which shows the best catalytic performance. 3Mn3V9WT powder catalyst exhibits enhanced NO conversion performance, i.e., ~ 95-98% with NH3 leakage < 20 ppm, for the temperature window of 260-320 °C in comparison with all other metal-doped 3V9WT catalyst powder. Manganese is the best substitute (50%) to vanadium in VWT catalyst without compromising the NO conversion performance even in presence of SO2 (1000 ppm), i.e., > 94% for the temperature of 300-320 °C. The recovery of SCR activity of the 3Mn3V9WT catalyst after SO2 effect was good, i.e., ~ 94% at 320 °C for long interval of time, where NH3 leakage was < 5 ppm.

Ultra-light poly(lactic acid)/SiO2 aerogel composite foam: A fully biodegradable and full life-cycle sustainable insulation material.

In this study, a fully biodegradable ultra-light poly(lactic acid)/silicon dioxide (PLA/SiO2) aerogel nanocomposite with ultra-low thermal conductivity was successfully fabricated. PLA used was a produced from lactic acid, where the lactic acid has been produced from carbohydrates. The rheological properties of PLA were enhanced by diphenylmethane diisocyanate (MDI). The foaming properties, cell density, cell size uniformity, mechanical properties and thermal conductivity and thermal diffusivity of PLA were further improved by SiO2 aerogel, and finally the ultra-low density foamed material was prepared by supercritical CO2. The density of PLA foam can be as low as 0.02 g/cm3 and the thermal conductivity as low as 0.02628 W/m·K. The PLA-based composites can be used in many fields such as thermal insulation, vibration damping and packaging, and can be fully biodegradable and sustainable throughout their life cycle, which meets the global trend of energy saving and emission reduction.