A novel electrochemical biosensor for the determination of dopamine and ascorbic acid based on graphene oxide /poly(aniline-co-thionine) nanocomposite

In this paper, we fabricated a sensitive and stable ascorbic acid (AA) and dopamine (DA) amperometric biosensor using nanobiocomposite derived from poly(aniline-co-thionine) (P(ANI-co-THI)) modified graphene oxide (GO). A simple one-step electrochemical deposition method was used to deposit P(ANI-co-THI) on GO/GCE to prepare graphene oxide/poly(aniline-co-thionine) (GO/P(ANI-co-THI)) composite modified electrode. The GO/P(ANI-co-THI) nanocomposite was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectroscopy. The electrochemical performance was evaluated by differential pulse voltammetry (DPV) in 0.2 M PBS solution (pH = 7). The modified electrode displayed excellent electrocatalytic activity toward AA (typically at - 0.09 V vs. SCE) and DA (typically at 0.176 V vs. SCE) and the oxidation peak current of AA and DA increased to 2.9 and 2.6-times of that at GO/GCE, respectively. Response to DA was linear in the concentration range of 0.002 to 0.5 mM with a detection limit of 2 mu M. Response to AA was linear in the concentration range of 0.5 to 5 mM with a detection limit of 242 mu M. Furthermore, the GO/P(ANI-co-THI)-based electrochemical sensor also exhibited high selectivity, good reproducibility and stability,wide detection range and low detection line.