Fe₃O₄@Ag@Pt nanoparticles with multienzyme like activity for total antioxidant capacity assay

A simple and reliable total antioxidant capacity (TAC) assay is essential for food safety evaluation and human health monitoring. Herein, a trimetallic nanozyme (Fe₃O₄@Ag@Pt) was synthesized and exhibited OXD-, POD- and SOD-like activities, which could generate a synergistic catalytic system. Fe₃O₄@Ag@Pt can catalyze oxygen to produce various reactive oxygen intermediates, and the endogenous product H₂O₂ could be captured and further dissociated efficiently into •OH, due to its strong substrate binding affinity. Since antioxidants can compete with TMB and lead to an antioxidant concentration-dependent color change, a colormetric sensing platform was constructed with a detection limit of 1.97 μM, 5.06 μM, and 8.99 μM for GSH, AA and Trolox, respectively. The proposed Fe₃O₄@Ag@Pt based assay was suitably employed to quantify TAC in fruit samples, beverages and cells with the aid of spike recovery and reference method validation, which hold vast promise as an analytical platform for food safety and biomedical diagnosis.