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

Abstract

Hexavalent chromium (Cr(VI)), as a highly biologically toxic heavy metal ion, poses great threats to environmental safety and human health. Herein, we report a facile and cost-effective colorimetric sensing platform for Cr(VI) detection based on Au nanoparticle-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 can catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) to its oxidized form, exhibiting a blue color. In the presence of 8-hydroxyquinoline (8-HQ), the catalytic activity of the prepared AuNPs/Fe–NC was inhibited, which weakened the AuNPs/Fe–NC-catalyzed oxidation of TMB. After Cr(VI) was introduced, the catalytic activity of AuNPs/Fe–NC nanozyme was recovered, resulting in an enhanced 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 toward a series of metal cations and was successfully applied to the detection of Cr(VI) in tap water.