Mesoporous silica stabilized Cu-Fe bimetallic nanozymes for total antioxidant capacity assay of fruit foods.

Total antioxidant capacity (TAC) is currently considered as a vital indicator of food quality in antioxidant ability and attracts much attention for human healthcare. It is thus of great significance to realize the accurate and rapid detection of TAC in foods. Herein, we have constructed a preferable hybrid nanozyme based on the mesoporous silica-stabilized CuO composited Fe3O4 nanoparticles (Fe3O4@MSNs@CuO, FMC NPs), which possess the enhanced peroxidase (POD)-like activity via cascade response for specific and sensitive determination of TAC in fruit foods. The results showed the hybrid nanozyme displayed a remarkable POD-like activity, excellent selectivity and sensitivity, and the limit of detection (LOD) of the colorimetric sensor was 6.13 mM with the concentration range from 10 to 45 mM. Therefore, the fabricated hybrid nanozyme can be regarded as an effective biosensor for the evaluation of antioxidant quality in fruit foods in future. KEY POINTS: • The stabilized bimetallic nanozyme was constructed for TAC analysis in fruits. • The hybrid nanozyme possessed the enhanced POD-like activity by cascading effects. • The nanozyme was an effective biosensor for antioxidant quality evaluation in fruits.