Department of Chemistry

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Department of Chemistry

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Browsing Department of Chemistry by Author "Adekunle, Abolanle S."

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    Electrochemical determination of serotonin in urine samples based on metal oxide nanoparticles/MWCNT on modified glassy carbon electrode
    (Published by Elsevier B.V, 2017-01-11) Fayemi, Omolola E.; Adekunle, Abolanle S.; Ebenso, Eno E.
    The electrochemical response of serotonin on the modified electrode based on multiwalled-carbon-nanotube (MWCNT) doped respectively with nickel, zinc and iron oxide nanoparticles coating on glassy carbon electrode (GCE) at physiological pH 7 was determined using cyclic voltammetry (CV) and square wave voltammetry (SWV). The modified GCE/MWCNT-metal oxide electrodes exhibited excellent electrocatalytic activity towards the detection of serotonin at large peak current and lower oxidation potentials compared to other electrodes in- vestigated. The dynamic range for the serotonin determinationwas between 5.98 × 10 −3 μM to 62.8 μMwithde- tection limits 118, 129 and 166 nM for GCE/MWCNT-NiO, GCE/MWCNT-ZnO and GCE/MWCNT-Fe 3 O 4 sensors respectively. GCE-MWCNT-NiO was the bestelectrode in terms of serotonin currentresponse, electrode stability, resistance to fouling and limit of detection towards the analyte.The developed sensors were found to be electro- chemicallystable, reusable, economically effective due to theirextremely low operational cost, and have demon- strated good limit of detection, sensitivity and selectivity towards serotonin determination in urine samples. © 2017 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
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    Phthalocyanine Doped Metal Oxide Nanoparticles on Multiwalled Carbon Nanotubes Platform for the detection of Dopamine
    (Springer publishing, 2017-03-03) Mphuthi, Ntsoaki; Adekunle, Abolanle S.; Fayemi, Omolola E.; Olasunkanmi, Lukman O.; Ebenso, Eno E.
    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 (0.75μM) which compared favourably with literature, good sensitivity (1.45μA/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.