Application of Graphite Screen Printed Electrode modified with Zinc Oxide Nanoparticle/Graphene for Voltammetric determination of Dopamine

Dopamine is a unique neurotransmitter as it possesses both excitatory and inhibitory classification. The abnormality in the amount of dopamine produced in the central nervous system is a sign of an underlying condition of a neurological disorder in the human body. The lower level of dopamine has been strongly related to illness such as Parkinson’s disease, restless leg syndrome, attention deficit hyperactivity disorder (ADHD), schizophrenia, and HIV infection. In the past few decades, various analytical methods have been established and described for the detection of dopamine [1]. Among many techniques, electrochemical method is a more suitable approach in evaluating the low concentration of dopamine under physiological conditions. Lately, SPE have been successfully used as the electrochemical sensor for various researches due to their disability, the simplicity of the apparatus, minimum sample preparation and obtaining of fast results. But, the use of the SPEs for determination of dopamine has been rarely reported, since the unmodified electrodes are unable to discriminate signals of dopamine [2]. Therefore, various inorganic and organic materials have been used to modify these electrodes. Among the nanostructure materials, zinc oxide (ZnO) with many extraordinary properties, including wide direct band gap, large exciton binding energy, nontoxicity, chemical and photochemical stability, high electrochemical activities and easy preparation has been introduced as one of the most promising candidates to modified electrodes [3]. Graphene (GR), which is a flat monolayer of carbon atoms tightly packed into a two dimensional honeycomb lattice, has drawn a great interest due to its unique structure, outstanding electrical, thermal, optical and mechanical properties and high specific 13th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 22- 23 Nov, 2017 73 surface area [4]. According to above mention, a sensitive and selective electrochemical sensor based on zinc oxide nanoparticles and graphene nanocomposite (ZnO/GR) for detection of dopamine (DA) has been successfully developed in present work. The electrochemical characteristics and catalytic behavior of prepared electrodes for the determination of dopamine were systematically investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimum conditions, the ZnO/GR/SPE exhibits linear response to dopamine in the range 0.5-100 μM, with detection limit (S/N = 3) calculated to be 0.1 μM. Finally, the developed sensor was successfully applied to the detection of dopamine in dopamine injection and urine samples with satisfactory results. The ZnO/GR nanocomposite show promising applications in the development of electrochemical sensors for chemical or biomolecules determinations.