We report a colorimetric method for glucose detection based on Au nanoparticle-decorated WSe2 (Au@WSe2) hybrid nanostructures. These hybrid structures are easily synthesized by simply stirring HAuCl4 precursor with WSe2 nanosheets in aqueous solution. Owing to strong synergistic catalytic effects of Au nanoparticles and WSe2 nanosheets, the Au@WSe2 hybrid nanostructures exhibit enhanced peroxidase-like activity (about 2-fold higher compared to WSe2 nanosheets alone) for 3,3’,5,5’-tetramethylbenzidine oxidation by H2O2. Based on the highly catalytical property, the colorimetric method for glucose detection is established by coupling glucose oxidase (GOx). The detection limit of glucose is 3.66 µM. Moreover, the proposed colorimetric method is applicable to glucose detection in serum samples and is promising for applications in biomedical fields.

A visual colorimetric detection strategy is reported for total antioxidant capacity (TAC) assay by using 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation as chromogenic substrate based on gold nanoparticle-decorated MoSe2 nanosheets (Au@MoSe2). Au@MoSe2 nanostructures exhibit high peroxidase-like activity and can catalyze H2O2 to oxidize TMB. Based on inhibition effect of ascorbic acid (AA) on TMB oxidation, a facile and sensitive colorimetric method was developed for AA detection. Under optimal conditions, the proposed method showed a sensitivity for AA in a concentration range from 2 to 120 µM and limit of detection was 0.41 µM. Furthermore, the method was employed for TAC assay in actual samples, including commercial beverages and vitamin C tablets. This work represents a model in nanostructure design and will lead to further development of TAC assay in evaluation of antioxidant food quality.

Organophosphorus pesticides can prevent or eliminate various pathogenic bacteria, insects, and weeds, and thus they are widely applied in agricultural production. However, illegal use and issues with organophosphorus pesticide residues contribute to global environmental pollution and pose a threat to public health safety. In this study, we developed a sensitive glyphosate (Glyp) fluorescence detection method using papain-stabilized gold nanoclusters (papain-AuNCs) as the fluorescence probe and a tyrosinase (TYR)/dopamine (DA) fluorescence-quenching system. The TYR catalyzed the oxidized conversion of DA into DA chrome, which served as an electron acceptor to quench the fluorescence of papain-AuNCs. However, Glyp inhibited the activity of TYR, thereby preventing DA oxidization and leading to the fluorescence recovery of papain-AuNCs. Under the optimum conditions, the fluorescence intensities of papain-AuNCs exhibited a good linear relationship with the concentration of Glyp in the range of 0.04–0.4 ng·mL−1, and the limit of detection for Glyp was 0.035 ng·mL−1. Furthermore, a paper-based sensor was constructed using the proposed system, which enabled on-site visual and semiquantitative detection of Glyp residues in tap-water samples. Overall, our strategy provides new opportunities for detection of organophosphorus pesticides and evaluation of environmental security.