Highly sensitive colorimetric detection of copper ions based on regulating the peroxidase-like activity of Au@Pt nanohybrids

Abstract

In this study, a sensitive colorimetric method for the detection of copper ions (Cu²⁺) was proposed based on regulating the peroxidase-like activity of Au@Pt nanohybrids (Au@PtNHs). It was found that L-cysteine can inhibit the catalytic ability of Au@PtNHs; however, it loses the inhibition toward the catalytic ability of Au@PtNHs after being oxidized by oxygen through the catalysis of Cu²⁺. The above phenomena were combined to develop a colorimetric detection method for Cu²⁺ through measuring the colorimetric signal variation of the H₂O₂–TMB reaction. This method exhibited high sensitivity and selectivity toward Cu²⁺ over a variety of other metal ions. The detection limit of this method was 4.0 nM with a linear range of 20–500 nM. Moreover, 20 nM Cu²⁺ can be distinguished directly by the naked eye. Furthermore, the proposed method was applied to the analysis of real samples with good accuracy, which demonstrated the excellent application potential of the proposed method.