Gold nanoparticle-decorated MoSe, 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 pM and limit of detection was 0.41 pM. 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.