Direct electrochemistry and electrocatalysis of hemoglobin immobilized on biocompatible poly(styrene-alternative-maleic acid)/functionalized multi-wall carbon nanotubes blends

In this study, we investigate the direct electron-transfer reactivity of immobilized hemoglobin (Hb) on a biocompatible poly(styrene-alternative-maleic acid) (PSMAC) copolymer/multi-walled carbon nanotubes (MWCNTs) blend for biosensor designs. The copolymer possesses good biocompatibility, uniformity, conformability and is ready for protein immobilization. On the other hand, electrochemical measurements show that the presence of MWCNTs provides a unique structure for interaction of Hb and copolymer and facilitate the direct electron transfer between the immobilized Hb and the surface conductivity. The immobilized Hb maintains its bioactivities and displays an excellent electrochemical behavior. The proposed method opens a way to develop biosensors by using nanostructured materials mixed with low electrical conductivity matrixes. The biosensor was used to catalyze the reduction of hydrogen peroxide. The electrocatalytic response showed a linear dependence on the H2O2 concentration ranging widely from 1.0 to 56.0 μM with a detection limit of 0.38 μM at 3σ.