An enzymatic biosensor for hydrogen peroxide based on CeO2 nanostructure electrodeposited on ITO surface.

In this study, an enzymatic biosensor for amperometric detection of hydrogen peroxide was developed based on the direct electrochemistry of myoglobin (Mb) on a porous cerium dioxide (CeO2) nanostructured film. The developed film accomplished with large surface area was electrodeposited on an indium tin oxide (ITO) substrate. Surface morphological studies revealed that the formed CeO2 film has a large specific surface area with a unique nanostructure on the ITO surface. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to demonstrate the electrochemical behavior of Mb immobilized on the fabricated film, which exhibited facile, direct electrochemistry and good electrocatalytic performance without any electron mediator. The electrode displayed a pair of quasi-reversible reduction-oxidation peaks at -0.3 and -0.2V, respectively, due to the Mb [Fe(3+)/Fe(2+)] redox couple, which is a surface-controlled electrochemical process with one electron transfer. This reagent-less biosensor showed good stability and high sensitivity for detecting H2O2 without any influence of intermediate compounds. This protein-based biosensor was capable of detecting H2O2 as low as 0.6μM with linearity up to 3mM and a response time of ~8s, compared to those of other modified electrodes. Hence, porous CeO2 is a possible candidate material for fabricating enzymatic sensors or devices.