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

A high-sensitive nonenzymatic hydrogen peroxide (H 2 O 2 ) biosensor based on cuprous iodide and graphene (CuI/Gr) composites has been explored for the detection of H 2 O 2 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 H 2 O 2 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 H 2 O 2 reduction with CuI/Gr nanocomposites deposited on graphite electrode. Hence, the as-prepared nonenzymatic H 2 O 2 biosensor could be used to detect H 2 O 2 release from different kinds of living cells under stimulation while eliminating the interference of ascorbic acid .