Gold nanoparticle-decorated MoSe₂ nanosheets as highly effective peroxidase-like nanozymes for total antioxidant capacity assay

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.