A third-generation biosensor for hydrogen peroxide based on the immobilization of horseradish peroxidase on a disposable carbon nanotubes modified screen-printed electrode

A screen-printed carbon nanotube (CNTs) based disposable third generation biosensor for hydrogen peroxide (H2O2) was constructed by mixing CNTs with a cellulose acetate binder on an epoxy substrate. The surface was covered with a layer consisting of horseradish peroxidase (HRP) crosslinked to bovine serum albumin with glutaraldehyde. The CNTs acted as both the electrode material and charge promoter to facilitate the direct electron transfer between immobilized HRP and the modified electrode. At a working potential of -300 mV (vs. Ag/AgCl), the biosensor displays an excellent electrocatalytic response to the reduction of H2O2 without the aid of a mediator. It has a fast (3 s) amperometric response and a linear calibration in the concentration range 0.005-0.1 mmol L-1, with a 0.85 mu M detection limit (at an S/N of 3). The biosensor can be easily produced, is stable and reproducible.