▎ 摘　　要

A non-enzymatic and highly electrocatalytic H2O2 biosensor was proposed by using a novel electrode composed of hemin-capped biomineralized gold nanoparticles (Hem@AuNPs), reduced graphene oxide (rGO) and chitosan (CS). Owing to the excellent electrocatalytic activity of Hem@AuNPs and great conductivity of rGO, this developed biosensor is capable of ultrasensitive measuring H2O2 in real-time. In addition, the introduction of CS resulted in a film on the electrode, which can enhance the stability by protecting the biosensor from external disturbances. Taking advantages of the peroxidase-like activities of the nanohybrids, the developed electrode exhibited outstanding electrochemical performance toward H2O2 with high selectivity, fast response, superior sensitivity and good stability. More importantly, the lower determination limit of 9.3 nM and wider linear ranges of 5 orders of magnitude enable this biosensor to detect H2O2 releasing from living Hela cells accurately. This work provides tremendous potential for real-time monitoring the secretion of H2O2 in living cells.