Preparation of polyaniline-TiO2 nanotube composite for the development of electrochemical biosensors

The significant and novel aspect of this work lies in the preparation of a polyaniline (PANI)-TiO2 nanotube (TNT) composite which can provide excellent biocompatibility, good electrical conductivity, low electrochemical interferences and high signal-to-noise ratio for the development of electrochemical biosensors. Using a hydrothermal method, TiO2 nanoparticles were initially transformed into TNTs, on which aniline was then polymerized by oxidative polymerization to form an intimate and uniform PANI-TNT composite. After being characterized by different spectroscopic techniques, the PANI-TNT composite was used to immobilize glucose oxidase (GOD) for the construction of an electrochemical biosensor. The direct electrochemistry and electro-catalytic performance of the biosensors based on PANI-TNTs and TNTs was studied by cyclic voltammetry. The direct electrochemistry of GOD on PANI-TNTs modified electrodes was achieved and the heterogeneous electron transfer rate constant (ks) for GOD was estimated to be 9.3 s−1. Furthermore, the redox currents of GOD at PANI-TNT modified biosensor were improved by ∼55% compared to that at TNT modified biosensor. The PANI-TNT modified GOD biosensor exhibited good sensitivity (11.4 μA mM−1), wide dynamic range (10-2500 μM) and low limit of detection (0.5 μM), which are attributed to the improved properties of the composite.