Cobalt-Doped Carbon Quantum Dots with Peroxidase-Mimetic Activity for Ascorbic Acid Detection through Both Fluorometric and Colorimetric Methods
Cheng Li, Jinjin Zeng, Ding Guo, Lei Liu, Liwei Xiong, Xiaogang Luo, Zhiyuan Hu, Fengshou Wu
Abstract
system. The change of fluorescence was linear with the concentration of AA (0.6-1.6 mM) with the LOD of 18 μM. Furthermore, the Co-CQDs exhibited high oxidase-like catalytic behavior, which could convert transparent 3,3',5,5'-tetramethylbenzidine (TMB) into blue ox-TMB by dissolved oxygen. After adding ascorbic acid to the Co-CQDs/TMB system, the blue color of the solution faded due to the reduction of blue ox-TMB to colorless TMB. Based on this phenomenon, the Co-CQDs were capable of detecting AA (10-400 μM) with the LOD of 0.27 μM. The fluorometric and colorimetric assays based on the Co-CQDs for the AA detection were then successfully applied in fresh fruits. Furthermore, the high biocompatibility of the Co-CQDs against HeLa cells was verified by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Thus, the Co-CQDs could be used as a powerful tool for the detection of AA in real samples through a dual-mode method.