Direct electrochemistry and electrocatalysis of hemoglobin incorporated in composite film based on diblock weak polyelectrolyte PHAEMA-b-PDMAEMA and multi-walled carbon nanotubes

Abstract

Abstract The new composite films composed of diblock weak polyelectrolyte poly(2-hydroxyethyl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate) (PHEMA-b-PDMAEMA, noted as PHD in the later content) and multi-walled carbon nanotubes (MWCNTs) were applied to immobilize hemoglobin (Hb) for biosensor fabrication. The characterization of Hb/PHD/MWCNTs films were demonstrated by ultraviolet–visible (UV–vis) spectra, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and typical amperometric response ( i – t ) measurements. The immobilized Hb maintains its bioactivities and displays an excellent electrochemical behavior. The modified electrode exhibited good electrocatalytic activity to the reduction of hydrogen peroxide (H 2 O 2 ). The linear response range of the H 2 O 2 biosensor was from 1.0 × 10 −6 to 1.5 × 10 −3 M with a detection limit of 3.5 × 10 −7 M. The apparent Michaelis–Menten constant of Hb on the PHD/MWCNTs film was estimated to be 0.51 mM. These results indicated that the composite films have potential applicability of new types third-generation biosensors or bioreactors based on direct electrochemistry of the proteins.