In situ synthesized H2O2 self-supplying composite peroxidase mimic CuO2@S/Cu-NC for portable detection of histamine and seafood freshness monitoring

The application of peroxidase-like nanozymes in on-site detection was often restricted due to the cumbersome operation caused by necessary step of adding H 2 O 2 . Herein, a novel composite peroxidase mimic CuO 2 @S/Cu-NC with self-supplying H 2 O 2 function was prepared by in situ synthesis of the copper peroxide nanodots (CuO 2 ) on the S/N co-doping carbon-based copper nanozyme (S/Cu-NC). The CuO 2 could produce H 2 O 2 in acidic environment, and the in situ formed H 2 O 2 could immediately bind to the active sites of S/Cu-NC, resulting in the greatly accelerated catalytic reaction efficiency. Because of the property of H + -induced H 2 O 2 production of CuO 2 @S/Cu-NC, the changes of pH value could affect its peroxidase-like activity. Therefore, a sensitive and convenient method for histamine sensing was established. Furthermore, a convenient test swab was designed for the portable histamine detection and visual monitoring the of seafood freshness, which showed great potential of multifunctional nanozyme in the field of food monitoring.