A novel nonenzymatic biosensor for evaluation of oxidative stress based on nanocomposites of graphene blended with CuI

•A novel nonenzymatic H2O2 electrochemical biosensor was constructed based on the CuI/Gr composites.•The biosensor has low detection limit and high sensitivity for H2O2 detection.•SECM imaging study further illustrates the electrochemical catalytic capability for H2O2 reduction.•The H2O2 biosensor is used to detect H2O2 released from living cells.

A high-sensitive nonenzymatic hydrogen peroxide (H2O2) biosensor based on cuprous iodide and graphene (CuI/Gr) composites has been explored for the detection of H2O2 released by living cells and monitoring the oxidative stress of cells under excellular stimulation. The biosensor properties were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), amperometric i-t curve, and the redox-competition mode of scanning electrochemical microscopy (SECM). Our observations demonstrate that the CuI/Gr nanocomposites modified glassy carbon electrode (GCE) exhibits excellent catalytic activity for H2O2 with relatively low detection limit and a wide linear range from 0.5 μM to 3 mM. Moreover, the redox-competition mode of SECM imaging study further illustrates the improved electrochemical catalytic capability for H2O2 reduction with CuI/Gr nanocomposites deposited on graphite electrode. Hence, the as-prepared nonenzymatic H2O2 biosensor could be used to detect H2O2 release from different kinds of living cells under stimulation while eliminating the interference of ascorbic acid.

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