Abstract
The electrocatalytic properties of metal oxides (MO = Fe3O4, ZnO) nanoparticles doped phthalocyanine (Pc) and functionalized MWCNTs, decorated on glassy carbon electrode (GCE) was investigated. Successful synthesis of the metal oxide nanoparticles and the MO/Pc/MWCNT composite were confirmed using UV-Vis, EDX, XRD and TEM techniques. Successful modification of GCE with the MO and their composite was also confirmed using cyclic voltammetry (CV) technique. GCE-MWCNT/ZnO/29H,31H-Pc was the best electrode towards DA detection with very low detection limit (0.75 μM) which compared favourably with literature, good sensitivity (1.45 μA/μM), resistance to electrode fouling, and excellent ability to detect DA without interference from AA signal. Electrocatalytic oxidation of DA on GCE-MWCNT/ZnO/29H,31H-Pc electrode was diffusion controlled but characterized with some adsorption of electro-oxidation reaction intermediates products. The fabricated sensors are easy to prepare, cost effective and can be applied for real sample analysis of dopamine in drug composition. The good electrocatalytic properties of 29H,31H-Pc and 2,3-Nc were related to their (quantum chemically derived) frontier molecular orbital energies and global electronegativities. The better performance of 29H,31H-Pc than 2,3-Nc in aiding electrochemical oxidation of DA might be due to its better electron accepting ability, which is inferred from its lower ELUMO and higher χ.
Highlights
Dopamine (DA) is a neurotransmitter in mammalian brain tissues that belongs to the family of inhibitory/catecholamine neurotransmitters
Shaidarova et al.[27] has reported determination of dopamine using electrode modified by a polyaniline film with an inclusion of copper (II) tetrasulfophthalocyanine
Fe3O4/29H, 31H-Pc system[34] and they have been considered as electrophotographic materials due to their absorption ability in the ultraviolet and visible region[35]
Summary
Carbon Nanotubes Platform for the received: 06 October 2016 accepted: 19 January 2017 Published: 03 March 2017 detection of Dopamine. The modified electrode resolved the overlapped voltammetric responses of ascorbic acid, dopamine and uric acid in to three well-defined cyclic voltammetric peaks These studies have employed metal nanoparticles (Cu, Ni, Co, or Fe) to doped Pc. in this work, metal oxide nanoparticles (ZnO and Fe3O4) are used because: (a) there is paucity of literature on the use of MO doped Pc for DA detection, (b) synthesis route for MO nanoparticles are shorter and cheaper compared with their metal nanoparticles counterparts, (c) devices based on metal oxides nanostructures are cost-effective, highly sensitive due to the large surface-to-volume ratio of the nanostructure and show excellent selectivity[8] and this is of paramount importance to the present study because of interferences from other molecules (d) the need to explore the electron transfer mechanism of MO modified electrodes which is fundamental to their application in sensors[12], (e) study in our group have shown that MWCNT-Fe2O3 modified electrode gave excellent separation of DA signal from AA even at AA concentration 1000 times that of DA12, (f) the detection of many analytes at trace concentration using MO modified electrodes have been reported[12,31].
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