Cu-doped and 2-propylimidazole-modified nanoceria (CeO2@Cu-PrIm) oxidase-like nanozyme for total antioxidant capacity assay of fruits

The precise and sensitive quantification of total antioxidant capacity (TAC) is indispensable for evaluating the quality of foods rich in antioxidants. In this investigation, a novel nanozyme exhibiting robust oxidase activity was synthesized via a sonochemical doping process utilizing copper ions and the modification of 2-propylimidazole onto nanoceria. Subsequently, a CeO2@Cu-PrIm/ox-TMB assay system was successfully formulated, furnishing a practical and highly sensitive analytical tool for TAC determination. The colorimetric sensor exhibited a linear response over a concentration range of 1 μM to 70 μM, accompanied by a limit of detection (LOD) of 1.26 μM under meticulously screened conditions. This assay displayed substantial practical utility for TAC analysis in fruits, attributed to its exceptional accuracy and selectivity. This research endeavor may offer a novel direction for the design of nanozymes and colorimetric biosensors possessing heightened oxidase activity, thereby advancing the field of analytical chemistry and food science. Schematic depicting the reaction system of CeO2@Cu-PrIm/ox-TMB assay for the determination of TAC.