Xiaoyan Pei,Dazhen Xiong,Jing Fan,Zhiyong Li,Huiyong Wang,Jianji Wang
In recent years, carbon nanodots (CDs) have attracted increasing attention in many applications because of their superior optical and chemical properties. To manipulate CDs properties for their smart applications, CDs with CO 2 switchable luminescence property have been designed and prepared in the present work. It is found that fluorescence of the polyamine-functionalized CDs can be switched “off” and “on” in DMSO-water mixture by alternatively bubbling and removal of CO 2 . 13 C NMR spectra suggest that the mechanism behind the fluorescence “on-off” results involves the reversible acid-base reaction of the functionalized CDs with CO 2 and the formation of hydrophilic polyammonium bicarbonates. Due to the poor solubility of polyammonium bicarbonates in DMSO-water mixture, the formation of the polyammonium bicarbonates precipitation, by CO 2 bubbling, decreases the concentration of the functionalized CDs in aqueous DMSO, leading to the switch off of the fluorescence. When CO 2 is removed by N 2 bubbling, the precipitation is returned to the DMSO-water mixture, and thereby the fluorescence is switched on again. Based on this novel CO 2 -switchable photoluminescence property, the functionalized CDs have been used for the quantitative detection of CO 2 and SO 2 in aqueous solution and in the air.
Lignin is a plentiful and readily accessible renewable resource. Vanillylamine is a crucial raw material used to synthesize pharmaceuticals and high-value furan compounds that can be acquired by aminating lignin-derived vanillin (Van). However, effectually achieving the biocatalytic synthesis of vanillylamine has remained challenging. In this study, a dimethyl sulfoxide (DMSO)-H 2 O (1:9, vol/vol) bioreaction medium was constructed, and a recombinant E. coli ATA1012 carrying ω-transaminase from Caulobacter sp. D5 was used as the ω-transaminase biocatalyst to acquire the effectual biocatalytic synthesis of vanillylamine. Under optimized bioreaction conditions (37 ℃ and pH 7.5) by supplementary of isopropylamine (IPA) (Van/IPA = 1:5, mol/mol), 80–100 mM Van could be effectually converted by ATA1012 whole cells in DMSO-H 2 O (1:9, vol/vol) within 12 h, yielding 91.2 %–95.4 % vanillylamine, with >99 % selectivity. An efficient amination process was developed using ATA1012 with superior transaminase catalytic activity and substrate tolerance to effectively convert Van to vanillylamine in a DMSO-H 2 O medium.
危险品化学品经营许可证（带存储）