The porous chitosan–sodium dodecyl sulfate–carbon nanotube nanocomposite: direct electrochemistry and electrocatalysis of hemoglobin

Abstract

A novel biosensor is developed based on immobilization of hemoglobin (Hb) on chitosan–sodium dodecyl sulfate–carbon nanotube composite modified glassy carbon electrode (Hb/CS–SDS–CNT/GCE). The surface morphologies of the modified electrode were characterized by SEM, and direct electrochemistry of Hb on Hb/CS–SDS–CNT/GCE was investigated by cyclic voltammetry (CV) and electron impedance spectroscopy (EIS). UV-vis spectroscopic results indicated that Hb molecules in the composite film retained the native structure. The results indicate that Hb immobilized on the surface of the modified electrode could keep its bioactivity, exhibiting a surface-controlled electrochemical process. The kinetic parameters for the electrode reaction, such as the formal potential (E°), the electron transfer rate constant (k_s), the apparent coverage (Γ), and Michaelis–Menten constant (K_m) are evaluated. Moreover, the immobilized Hb also displayed its good electrocatalytic activity for the reduction of hydrogen peroxide with a low detection limit of 4.2 μM and good stability and reproducibility. The results demonstrate that porous CS–SDS–CNT composite can improve the Hb loading with retention of its bioactivity, and greatly promote the direct electron transfer, which can be attributed to its high specific surface area, uniform ordered porous structure, suitable pore size and biocompatibility.