Evaluation of the Growth-Inhibitory Spectrum of Three Types of Cyanoacrylate Nanoparticles on Gram-Positive and Gram-Negative Bacteria.

The development of novel effective antibacterial agents is crucial due to increasing antibiotic resistance in various bacteria. Poly (alkyl cyanoacrylate) nanoparticles (PACA-NPs) are promising novel antibacterial agents as they have shown antibacterial activity against several Gram-positive and Gram-negative bacteria. However, the antibacterial mechanism remains unclear. Here, we compared the antibacterial efficacy of ethyl cyanoacrylate nanoparticles (ECA-NPs), isobutyl cyanoacrylate NPs (iBCA-NPs), and ethoxyethyl cyanoacrylate NPs (EECA-NPs) using five Gram-positive and five Gram-negative bacteria. Among these resin nanoparticles, ECA-NPs showed the highest growth inhibitory effect against all the examined bacterial species, and this effect was higher against Gram-positive bacteria than Gram-negative. While iBCA-NP could inhibit the cell growth only in two Gram-positive bacteria, i.e., Bacillus subtilis and Staphylococcus aureus, it had negligible inhibitory effect against all five Gram-negative bacteria examined. Irrespective of the differences in growth inhibition induced by these three NPs, N-acetyl-L-cysteine (NAC), a well-known reactive oxygen species (ROS) scavenger, efficiently restored growth in all the bacterial strains to that similar to untreated cells. This strongly suggests that the exposure to NPs generates ROS, which mainly induces cell growth inhibition irrespective of the difference in bacterial species and cyanoacrylate NPs used.

Selective monoallylation of anilines to N-allyl anilines using reusable zirconium dioxide supported tungsten oxide solid catalyst.

The monoallylation of aniline to give N-allyl aniline is a fundamental transformation process that results in various kinds of valuable building block allyl compounds, which can be used in the production of pharmaceuticals and electronic materials. For decades, sustainable syntheses have been gaining much attention, and the employment of allyl alcohol as an allyl source can follow the sustainability due to the formation of only water as a coproduct through dehydrative monoallylation. Although the use of homogeneous metal complex catalysts is a straightforward choice for the acceleration of dehydrative monoallylation, the use of soluble catalysts tends to contaminate products. We herein present a 10 wt% WO3/ZrO2 catalyzed monoallylation process of aniline to give N-allyl anilines in good yields with excellent selectivity, which enables the continuous selective flow syntheses of N-allyl aniline with 97-99% selectivity. The performed detailed study about the catalytic mechanism suggests that the dispersed WO3 with the preservation of the W(vi) oxidation state of 10 wt% WO3/ZrO2 with appropriate acidity and basicity is crucial for the monoallylation. The inhibition of the over allylation of the N-allyl anilines is explained by the unwilling contact of the N-allyl aniline with the active sites of WO3/ZrO2 due to the steric hindrance.

Synthesis of Fluoride-Containing High Dimensionally Structured Nb Oxide and Its Catalytic Performance for Acid Reactions.

High dimensionally structured niobium oxide (HDS-NbO) containing fluoride (F-) was prepared by a hydrothermal synthesis. F- could be introduced into HDS-NbO by replacing lattice oxygen up to a solid F-/Nb ratio of 0.55. The introduction of an appropriate amount of F- promoted the crystal growth of HDS-NbO, while niobium oxyfluoride having the hexagonal tungsten bronze structure (HTB-Nb(F,O)x) was concomitantly formed by excess F- addition. HAADF-STEM analysis suggested that the number of micropores (hexagonal and heptagonal channels) in HDS-NbO was increased by the introduction of an appropriate amount of F-. The catalytic activity for Brønsted acid reactions was evaluated by Friedel-Crafts alkylation. The catalytic activity was significantly increased by the introduction of F-, while excess introduction of F- significantly decreased the activity. Catalytic activity for the Lewis acid reaction in the presence of water was evaluated by the transformation of pyruvaldehyde into lactic acid. The catalytic activity was changed by the introduction of F- in a manner similar to that observed in the Friedel-Crafts alkylation. On the basis of the results obtained, we propose that the local catalyst structure around the micropores of HDS-NbO is crucial for the acid reactions.