▎ 摘　　要

A novel, sensitive, nonenzymatic amperometric sensor for the reliable detection of extracellular H2O2 released from living cells was fabricated based on Fe3O4/reduced graphene oxide (Fe3O4/rGO) nanocomposites, which were prepared using a simple and cost-effective one-pot approach. Electrochemical performances of the Fe3O4/rGO nanocomposites modified glassy carbon electrode (GCE) were studied. The results demonstrated that this H2O2 sensor exhibited excellent electrocatalytic performance towards the reduction of H2O2 at a potential of -0.3 V in the wide linear concentration range from 0.001 to 20 mM with a high sensitivity of 387.6 mu A mM(-1) cm(-2) and a detection limit as low as 0.17 mu M (S/N = 3), which was lower than certain enzymes and noble metal nanomaterials-based biosensors. Moreover, good anti-interference property, reproducibility, and long-term stability of the enzymeless sensor were achieved. Because of these remarkable analytical advantages, a novel, effective approach for the detection of extracellular H2O2 released from HeLa cells stimulated by CdTe quantum dots (QDs) was established by the constructed sensor. Since H2O2 is a byproduct of several oxidative biological reactions, this work could be applied to study the downstream biological effects of various stimuli in pathophysiology, and may expand the application of Fe3O4-based nanomaterials in the field of electrochemical sensing and bioanalysis.