Electrochemical and Electrocatalytic Properties of Platinum Electrode Modified With Gold-CNT Nanocomposite

Dopamine (DA) is an important neurotransmitter in the mammalian central nervous, hormonal and renal system [1]. It can cause Parkinson’s disease (when in low amount) and other similar diseases [2]. Epinephrine, (EP) on the other hand belongs to the group of substances known as catecholamine neurotransmitters which include norepinephrine and dopamine [3]. They are mainly important for message transfer in the mammalian central nervous system (CNS). Changes in concentration of epinephrine in the body can result in many diseases such as Alzheimer’s disease and aging effect. Therefore, various analytical methods to detect these analytes have been developed in the past. Some examples of these methods are the liquid chromatography, mass spectrometry, gas chromatography methods, and capillary electrophoresis mass spectrometry method. These methods require several derivatization procedures which are time consuming and very expensive. It is also known that with a bare electrode the oxidation peaks of DA and AA are at nearly same potential, which results in the overlapped voltammetric responses making their discrimination very difficult. Thus, motivation to this work is to fabricate sensitive, specific and selective sensors that would discriminately detect DA and EP in the presence of other interfering species such as ascorbic and uric acids. An electrochemical method was employed since it provides a simple, cost effective and quick way of analyzing biologically and environmentally important molecules.

In this study, the electron transfer and electrocatalytic properties of gold nanoparticle catalysts supported on MWCNTs/platinum modified electrode were described. The Pt-MWCNT-Au and Pt-MWCNT-AuO and the other modified electrodes were successfully characterised with FESEM, HRTEM, XRD, EDX, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The MWCNT-Au based electrodes demonstrated fastest electron transport and current response towards DA and EP compared to the other electrodes studied, with a relatively high catalytic rate constant, high sensitivity and nano molar (10^-9 M) limit of  detection. The electrode can detect DA and EP without interference from ascorbic acid (AA) signal. The electrode demonstrated good potential towards DA detection in real drug sample analysis.

REFERENCES:

1. N.Q. Jia, Z.Y. Wang, G.F. Yang, H.B. Shen and L.Z. Zhu,  Electrochem. Commun., 9, pp 233, 2007

2. Q. Wang, N. Jiang and N. Li, Microchemical Journal, 68, pp 77, 2001

3. P. Hernandez, O. Sanchez, F. Paton and L. Hernandez, Talanta, 46, pp 985, 1998