A novel biosensing mechanism based on a poly(N-butyl benzimidazole)-modified gold electrode for the detection of hydrogen peroxide

A novel mechanism to detect hydrogen peroxide (H₂O₂) using a poly(N-butyl benzimidazole) (PBBI)-modified gold (PBBI/Au) electrode is proposed. Synthetic PBBI was oxidized using a mixture of acetic acid (AcOH) and H₂O₂ to form PBBI N-oxide (PBBINO). The structure of PBBINO was verified by Fourier transform infrared spectroscopy (FT-IR) and the degree of oxidation was measured by X-ray photoelectron spectroscopy (XPS). Moreover, the oxide could be reduced electrochemically back to PBBI. Based on this reaction, a novel enzyme-free PBBI/Au electrode was developed to detect H₂O₂ in the presence of AcOH electrochemically. The biosensor detected H₂O₂ linearly over concentrations ranging from 25μM to 10mM with a detection limit of 6.25μM in phosphate buffer solution (PBS) mixed with AcOH at pH 6.4. In addition, at an applied potential of -0.5V, the sensor characteristics could be tuned using AcOH over a pH range of 3.7-6.4. The sensitivity of the probe could be enhanced from 35.1 to 419.4μAmM^-1cm^-2 by modifying the surface morphology of the PBBI/Au electrode from a smooth plane to a granular, three-dimensional configuration. Furthermore, it was not influenced by interfering compounds and showed high thermal stability.