Colorimetric determination of biothiols with AuNPs@MoS2 NSs as a peroxidase mimetic enzyme

Abstract

AuNPs@MoS₂ NSs with high peroxidase-like activity were prepared and used for the colorimetric determination of biothiols. The synergistic effect between gold nanoparticles (AuNPs) and MoS₂ nanosheets (MoS₂ NSs) accelerated the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂ to form the blue oxidized TMB (oxTMB) with an absorption peak at 652 nm. However, the AuNPs@MoS₂ NS-catalyzed TMB oxidation could be inhibited by biothiols, resulting in an absorbance decrease. Under the optimized experimental conditions, the signal responses to homocysteine (Hcy), glutathione (GSH), and cysteine (Cys) were linear in the range from 1.0 to 100 μmol L⁻¹, and the limit of detection of these biothiols was 0.93, 0.71, and 0.73 μmol L⁻¹, respectively. The suggested method was successfully applied for the determination of Hcy in human serum samples with a recovery of 97.7–101.2%, indicating the potential application of this method for biothiol sensing in real samples.