Browsing by Author "Masikini, Malua"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Application on gold nanoparticles-dotted 4-nitrophenylazo graphene in a label-free impedimetric deoxynivalenol immunosensor(MDPI, 2015) Sunday, Christopher Edozie; Masikini, Malua; Wilson, Lindsay; Rassie, Candice; Waryo, Tesfaye T.; Baker, Priscilla; Iwuoha, Emmanuel I.In this paper, we report a new concept to construct a label-free electrochemical inhibition-based immunosensor for the detection of the mycotoxin deoxynivalenol (DON) in cereal samples. The electrochemical impedance spectroscopy of tris(bipyridine) ruthenium (II) chloride was used as a marker enhanced with gold nanoparticles-dotted 4-nitrophenylazo functionalized graphene (AuNp/G/PhNO2) nanocatalyst mediated in Nafion on a glassy carbon electrode. Under the optimized conditions, the formation of immunocomplexes inhibited electron flow and increased the charge transfer resistance of the sensing interface linearly. The change in impedance was proportional to DON concentrations in the range of 6–30 ng/mL with a sensitivity and detection limit of 32.14 ΩL/ng and 0.3 µg/mL, respectively, which compares favorably with the ELISA result. The proposed sensor had a stability of 80.3%, good precision and selectivity in DON standard solution containing different interfering agents, indicating promising application prospect for this strategy in designing impedimetric, electrochemiluminescent, voltammetric or amperometric sensors.Item An electrochemically active green synthesized polycrystalline NiO/MgO catalyst: Use in photo-catalytic applications(Elsevier, 2018) Fuku, X.; Matinise, N.; Masikini, Malua; Kasinathan, K.; Maaza, MalikFor many years, research scientists have aided communities in their tremendous efforts towards environmental remediation. Due to their high physical and chemical stability, metal oxide nanoparticles (NPs) have been used as metal catalysts to remedy this issue. This article reviews green approaches for the synthesis of metal oxide nanoparticles, in aqueous bio-reductive polyphenols from punica granatum peel extract and the degradation of organic pollutants. The bimetallic nanocomposite of face-centred cubic NiO/MgO pseudocapacitors were successfully prepared via the polyphenols of punica granatum peel extracts. X-ray diffraction spectroscopy (XRD) successfully provide evidence of polycrystalline face-centre cubic nanocomposite (high crystallinity index (Icry) > 1) while revealing their interplanar distance. The spherical and irregular particle distribution of the binary NiO/MgO nanocomposite (at different calcination temperatures) was assessed by high resolution-TEM. FTIR, GC–MS and EDS provided evidence of the proposed mechanism during coordination between polyphenols and metal precursors. The popular “egg box model” is referred to in the case of polyphenols-metal interaction. The unique feature of two consecutive chelation site per repeat that provides a favourable entropic contribution to the inter-chain association is produced by this model governed by electrostatic interactions. Based on the obtained results, new structural models of Ni2+/Mg2+-polyphenols (punicalagin) complexes were proposed. UV–vis and Cyclic voltammetry confirmed the growth and band gap energies of the nanocomposite. NiO/MgO nanocomposite was found to be excellent photocatalysts for the degradation of methylene orange and methylene blue under the illumination of artificial light irradiation. The experiments demonstrated that MB in aqueous solution was more efficiently photo-degraded (87%) than MO (73%) using NiO/MgO nanocomposite as photocatalysts within 10 min of exposure. Conclusively, the nanocomposite was found to be more efficient compared to other reported oxides.Item A fumonisins immunosensor based on polyanilino-carbon nanotubes doped with palladium telluride quantum dots(MDPI, 2015) Masikini, Malua; Tsegaye, Abebaw; Mailu, Stephen N.An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)- multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L−1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng−1 and 0.46 pg L−1 , respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg−1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2–4 mg L−1 ).