Investigation on the synergy mechanism of mixed inhibitors – Mannich base and Na2WO4 on Fe surface by molecules dynamic simulation

Chiral carbon dots - a functional domain for tyrosinase Cu active site modulation via remote target interaction

The nano-hybrid enzyme is an ideal catalytic system that integrates various advantages from biocatalysis and nanocatalysis into homogeneous and heterogeneous catalysis. However, great efforts are still needed to fully understand the interactions between nanoparticles and enzymes. Here, we show chiral carbon dots (CDs) as a new functional domain for tyrosinase Cu active site modulation via remote target interaction. Three kinds of chiral CDs (LCDs-1/-2/-3; DCDs-1/-2/-3) were fabricated by thermal treatment of citric acid and L/D-aspartic acid. Then a series of CDs/tyrosinase composites (namely, nano-hybrid-enzymes) were prepared, demonstrating good regulation of enzyme catalytic kinetics. Especially, we find that LCDs-1 is an irreversible inhibitor with great inhibition effect while the others are all reversible inhibitors. Furthermore, it is suggested by both experiments and all-atom molecular dynamics simulations that the joint effect of LCDs-1 and tyrosinase makes LCDs-1 serve as a new functional domain, which has a distinguished ability to control the conformational changes of the key sites of the active center of the tyrosinase (e.g., H60) and thus the escaping behavior of copper ions and the catalytic activity. This work opens a new route for nano-hybrid-enzyme design and enzyme activity regulation with chiral carbon materials as functional domains via remote target interaction.

Electrochemical and thermodynamic properties of 1-phenyl-3-(phenylamino)propan-1-one with Na2WO4 on N80 steel

The corrosion inhibition effect and adsorption behaviour of 1-phenyl-3-(phenylamino)propan-1-one (PPAPO) on N80 steel in hydrochloric acid solution have been investigated by Fourier transform infrared (FTIR), electrochemical method and scanning electron microscopy. The corrosion inhibition mechanism of PPAPO mixed with Na2WO4 was interpreted from the thermodynamic point of view. The results indicated that PPAPO mixed with Na2WO4 acted as a mixed-type inhibitor. The inhibition film formed on N80 steel surface can increase the charge transfer resistance and prevent the occurrence of corrosion reaction, thereby reducing the corrosion rate of metal surface. The inhibition efficiency was up to 96.65%; the inhibitor PPAPO with Na2WO4 showed good synergistic effect on N80 corrosion behaviour in HCl solution. The adsorption behaviour of inhibitors on N80 steel surface was in accordance with the Langmuir adsorption model and mainly belonged to chemisorption. The adsorption process of PPAPO on N80 surface was spontaneous and irreversible endothermic reaction.