Direct electrochemistry and electrocatalysis of hemoglobin on polypyrrole-Fe3O4/dodecyltrimethylammonium bromide-modified carbon paste electrode and its biosensing for hydrogen peroxide

Abstract

A novel hydrogen peroxide (H₂O₂) biosensor was successfully constructed, based on the immobilization of hemoglobin (Hb) on polypyrrole (PPy)-Fe₃O₄ and dodecyltrimethylammonium bromide (DTAB) composite ?lm-modified carbon paste electrodes (CPE). The PPy-Fe₃O₄ composites were synthesized in the suspension solution of Fe₃O₄ nanoparticles via in situ chemical oxidative polymerization under the direction of cationic surfactant cetyl trimethyl ammonium bromide. Spectroscopic and electrochemical examinations illustrated that the PPy-Fe₃O₄/DTAB composites were a biocompatible matrix for immobilizing Hb, which revealed high chemical stability and excellent biocompatibility. The thermodynamic, dynamic, and catalytic performance of the biosensor were analysed using cyclic voltammetry (CV). The results indicated that the PPy-Fe₃O₄/Hb/DTAB/CPE exhibited excellent electrocatalytic activity in the reduction of H₂O₂ with a high sensitivity (104 μA mM^{? 1}). The catalytic reduction currents of H₂O₂ were linearly related to H₂O₂ concentration in the range from 2.5 μM to 60 μM with a detection limit of 0.8 μM (S/N = 3). With such superior characteristics, this biosensor for H₂O₂ can be potentially applied in determination of other reactive oxygen species as well. These results indicated that PPy-Fe₃O₄/DTAB composites are a promising matrix for bioactive molecule immobilization.