A colorimetric sensor for detecting thiourea based on inhibiting peroxidase-like activity of gold–platinum nanoparticles

Abstract

In this study, gold–platinum nanoparticles (Au@PtNPs) with peroxidase-like activity were synthesized. In the absence of thiourea (TU), the Au@PtNPs can catalyze the decomposition of hydrogen peroxide, and oxidize 3,3′,5,5′-tetramethylbenzidine dihydrochloride (TMB, colorless) into oxidized 3,3′,5,5′-tetramethylbenzidine dihydrochloride (oxTMB, blue). The peroxidase-like activity of the Au@PtNPs is inhibited in the presence of TU, and TMB cannot be oxidized to oxTMB effectively, and no blue color could be observed. Based on this finding, a novel colorimetric sensor for detecting TU is proposed. The absorbance response curve showed a good linearity for the concentration of TU in the range of 10 nmol L⁻¹ to 10 μmol L⁻¹ with a correlation coefficient of R² = 0.999, and the limit of detection is 9.57 nmol L⁻¹. The colorimetric sensor possesses excellent selectivity, anti-interference ability, and application value in actual samples.