A New Amperometric Biosensor Based on HRP/Nano-Au/L-Cysteine/Poly(o-Aminobenzoic acid)-Membrane-Modified Platinum Electrode for the Determination of Hydrogen Peroxide

The third generation amperometric biosensor for the determination of hydrogen peroxide (H₂O₂) has been described. For the fabrication of biosensor, o-aminobenzoic acid (oABA) was first electropolymerized on the surface of platinum (Pt) electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase (HRP) absorbed by nano-scaled particulate gold (nano-Au) was immobilized on the electrode modified with polymerized o-aminobenzoic acid (poABA) with L-cysteine as a linker to prepare a biosensor for the detection of H₂O₂. Amperometric detection of H₂O₂ was realized at a potential of +20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10⁻⁶ to 3.55×10⁻³ mol·L⁻¹ to H₂O₂ with a sensibility of 0.0177 A·L⁻¹·mol⁻¹ and a detection limit (S/N=3) of 4.3×10⁻⁷ mol·L⁻¹. The biosensor demonstrated a 95% response within less than 10 s.