Three-dimensional hierarchically porous carbon nanozymes with peroxidase-like activities for sensitive detection of TAC

Antioxidants are effective in scavenging free radicals in the human body and the intake of antioxidant-rich foods in the daily diet can help prevent diseases. In order to classify antioxidant-containing beverages and control food quality, our project develops a rapid, widely applicable, and accurate method to determine the total antioxidant capacity (TAC) in beverages. 3D honeycomb-like nitrogen-doping carbon nanozymes were successfully prepared by the template-free and pyrolysis methods. A series of instruments were employed to investigate the morphology, composition and pore structure information of carbon nanozymes. Among them, NC-900 with its rich mesoporous structure was capable of rapidly transferring electrons to catalyze the oxidation of TMB by H 2 O 2 . NC-900 exhibited the best peroxidase-like activity at pH 4, reaction time of 10 min, and enzyme concentration of 26 µg/mL. The maximal reaction rate of NC-900 towards substrates TMB and its affinity for H 2 O 2 were higher than that reported carbon nanozymes. Using reductants such as AA as antioxidant models, the NC-900-based sensor was characterized by wide detection range, low detection limit and high selectivity. The successful use of this approach to assess TAC in commercial beverages broadened the conceivable applications of carbon nanozymes. The present method shows a broad application prospect of carbon nanozyme in food analysis and human health.