Electrooxidation of dopamine at N -(l,3-dimethylbutyl)- N′ -phenyl- p -phenylenediamine/multiwalled carbon nanotubes nan

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nanocomposite-modified electrode has been prepared by functionalizing multiwalled carbon nanotubes (MWCNTs) with N-(1,3-dimethylbutyl)-N9-phenyl-p-phenylenediamine (p-PDA). The physical characterization of the prepared composite has been done using infrared spectroscopy and ultraviolet-visible spectroscopy. The morphologies of the prepared p-PDA/MWCNTs/ionophore film have been characterized using scanning electron microscopy and transmission electron microscopy. The electrochemical studies of the prepared composite electrode have been investigated by cyclic voltammetry technique. We observed that the p-PDA/MWCNTs/ionomer composite has better electrochemistry, film adhesion with homogeneous dispersion at the electrode surface and an electrocatalytic activity toward the oxidation of dopamine (DA) in 0.1 M phosphate buffer solution (pH 7.0) at a potential of 50 mV. The linear range and detection limit for the detection of DA was found to be 62–625 and 5 lM respectively. The modified electrode also exhibited several attractive features such as simple preparation, fast response, good stability and repeatability.

I. INTRODUCTION

Dopamine (DA) is a monoamine neurotransmitter found in mammalian brain and is essential for the normal functioning of the central nervous system.1 It is one of the most important neurotransmitters and plays a significant role in the functioning of central nervous system, as also the renal and hormonal systems. Abnormal levels of DA causes neurological disorders such as Parkinson’s disease, schizophrenia, Alzheimer’s disease2–4 and Huntington’s chorea.5 DA is widely applied to the treatment of circulatory collapse syndrome, which is a medical emergency, caused by myocardial infarction, trauma, renal failure, recent cardiac surgery, or congestive cardiac failure.6,7 Therefore, it is important to develop a sensor for the detection of DA. DA is an electroactive compound but its electroactivity suffers on conventional electrodes. Moreover, interferences from various other metabolic analytes like ascorbic acid (AA), which is essential for skin, connective tissues and immune system and uric acid (UA), which is the final oxidation product of the urine metabolism, present in real samples impose further limitations on the effectiveness of electrodes. Hence, there is a need to develop modified electrodes to improve the speed of electron transfer, sensitivity, detection limit and to lessen the electrocatalytic oxidation/reduction potential. a)

Address all correspondence to this author. e-mail: [email protected], [email protected] DOI: 10.1557/jmr.2013.87 J. Mater. Res., Vol. 28, No. 13, Jul 14, 2013

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Various reports are available detailing the ongoing attempts for modification of electrode with materials having good electroactivity like metal nanoparticles,8,9 conductive polymers,10–13 carbon nanotubes.14,15 Among these, carbon nanotubes (CNTs) have attracted much attention due to their high chemical stability, high surface area, unique electr