Novel Au-anchored Fe-NC nanozyme enabled rapid and sensitive colorimetric detection of Cr(VI)

Abstract

Hexavalent chromium (Cr(VI)), as a high biologically toxic heavy metal ion, poses a great threat to environmental safety and human health. Herein, we report a facile and cost-effective colorimetric sensing platform for Cr(VI) detection based on Au nanoparticles-anchored Fe-NC nanozyme (AuNPs/Fe-NC) catalysis. The AuNPs/Fe-NC nanozyme shows comparable catalytic activity and kinetics to natural horseradish peroxidase (HRP), which could catalyze 3,3’,5,5’-tetramethylbenzidine (TMB) to its oxidized form with a blue color. In the presence of 8-hydroxyquinoline (8-HQ), the catalytic activities of prepared AuNPs/Fe-NC was inhibited, which weaken AuNPs/Fe-NC-catalyzed oxidation towards TMB. After Cr(VI) was introduced, this catalytic activity of AuNPs/Fe-NC nanozyme could be recovered, resulting in an increasing blue color. By monitoring the variation of UV-vis absorbance, Cr(VI) had been quantified analysis and shown excellent sensitivity with the detection limit as low as 0.25 μM, and the linear range was 1-165 μM. It also exhibited high selectivity for a series of metal cations, and had been successfully applied to the detection of Cr(VI) in tap water.