Layer-by-layer assembly of hemoglobin and DNA functionalized carbon nanotubes on glassy carbon electrode: Direct electrochemistry and electrocatalysis

Abstract

Layer-by-layer assembly of hemoglobin (Hb) with DNA functionalized singlewall carbon nanotubes (DNA-SWCNTs) was achieved on glassy carbon electrode surface based on the electrostatic attraction between positively charged Hb and negatively charged DNA-SWCNTs hybrids. Cyclic voltammogram of (Hb/DNA-SWCNTs)n films modified electrodes showed a pair of well-defined and quasireversible redox peaks for Hb Fe(III)/Fe(II), indicating that direct electrochemistry of Hb was achieved. The dependence of the formal potential on solution pH indicated that oneproton transfer was coupled to each electron transfer in the direct electron transfer reaction. Additionally, Hb in the multilayer films retained its bioactivity and showed excellent electrocatalytic activity toward H2O2, suggesting that such multilayer films could be used as reagentless biosensors. The electrocatalytic current values were linear with increasing concentration of H2O2 in a wide range of 1-80μM, with a low detection limit of 0.2μM. The layer-bylayer assembly of enzymes with DNA-SWCNTs hybrids provided a general and useful way to construct sensitive biosensors without using mediators. On the other hand, this would be used as an easily prepared experimental model to fabricate functional nanostructured biointerfaces.