A graphene oxide/conducting polymer nanocomposite for electrochemical dopamine detection: origin of improved sensitivity and specificity†
Neuromodulatory dopamine (DA) acts as an essential signaling molecule in the central nervous system (CNS), and its dysfunction has been implicated in neurological disorders such as Parkinson's disease and schizophrenia. Due to its inherent redox properties, DA can be detected electrochemically by monitoring changes in current as the molecule is oxidized. Many electrode materials for electrochemical detection have been developed to monitor DA, but properties such as sensitivity and specificity must be optimized. We describe a conducting polymer (CP) nanocomposite of poly(3,4-ethylendioxythiophene) (PEDOT) doped with GO nanosheets, and report its superior DA detection performance over bare glassy carbon electrode (GCE) substrates. The GO/PEDOT electrode exhibits favorable electrical properties such as lowered impedance and increased charge storage capacity. The nanocomposite demonstrates improved sensitivity to the oxidation of DA at its surface. Meanwhile, interference from competing analyte, ascorbic acid (AA), is minimized. Mechanistic studies indicate that electrostatic interactions drive the increased sensitivity toward DA, and improved electrocatalysis of AA oxidation by the nanocomposite enables the selective discrimination of DA signals from those of AA. The described performance of the GO/PEDOT nanocomposite accentuates its promise for improving detection capabilities of electrochemical biosensors for the accurate and reliable detection of DA signals in biological samples.