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Effect of surface modification on the peroxidase-like behaviors of carbon dots
- Shi, Jing, Yin, Tianxiang, Shen, Weiguo
- Colloids and surfaces 2019 v.178 pp. 163-169
- biocompatibility, carbon quantum dots, catalytic activity, citric acid, electron transfer, ethyleneimine, hydroxyl radicals, oxidation
- Carbon dots (CDs) have drawn much attention in recent decades due to their outstanding biocompatibility and environmental friendliness. In this work, the surface modifications of peroxidase-like carbon dots were carried out to show the influence of surface structure on the catalytic activity. Poly(ethyleneimine) and citric acid modified CDs, i.e. PEI-CDs and CA-CDs, were obtained and used in the catalytic oxidation of two different substrates 3,3',5,5'-tetramethylbenzidine (TMB) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The catalytic activity of CA-CDs for TMB is greater than that of unmodified CDs while the catalytic activity of PEI-CDs for ABTS is greater than that of unmodified CDs. These results may be ascribed to that TMB shows stronger affinity to negatively charged CA-CDs and ABTS shows stronger affinity to positively charged PEI-CDs. These results clearly suggested that the surface charge plays an important role in the catalytic activity of nanoenzyme. Furthermore, the mechanism of peroxidase-like activity of all CDs was investigated and both the generation of hydroxyl radical and enhanced electron transfer were involved in the catalytic process.