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    Acetylsalicylic acid assisted hydrothermal growth of NiO, CuO and Co3O4 nanostructures and their application in the electro-catalytic determination of nalbuphine hydrochloride
    (ELSEVIER SCIENCE SA, 2017) Kalwar, Nazar Hussain; Tunesi, Mawada Mohamed; Soomro, Razium Ali; Amir, Md.; Avci, Ahmet; Hallam, Keith Richard; Kilislioglu, Ayben
    This study describes the hydrothermal synthesis of NiO, CuO and Co3O4 nanostructures using acetylsalicylic acid (ASA) as a growth-controlling/directing agent. The as-synthesised nanostructures were shown to possess unique structural features and distinct morphologies, portraying the efficiency of ASA as a suitable growth modifier. The formed metal oxide nanostructures, when used for electrode modification purposes, exhibited excellent electrocatalytic capabilities against the oxidation of nelbuphine hydrochloride (NAL) in aqueous buffer solution. The modified electrodes exhibited distinct electrochemical characteristics, with CuO-based electrodes exhibiting a superior signal sensitivity and lower over-potential value compared to the NiO and Co3O4 nanostructures. The study further explores the variation in the observed electro-catalytic oxidation signal referenced to the distinct morphologies of the metal oxides nanostructures. The CuO-based electrode was selected for the sensitive quantification of NAL in aqueous solution over the linear range 0.001-2.25 mu M. The electrode demonstrated excellent working linearity, with signal sensitivity achieved down to 1 x 10(-4) mu M. Moreover, the successful quantification of NAL in complex matrices, such as human urine and clinical waste water, further reflected the analytical capability of the proposed sensor.
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    Functionalised CuO nanostructures for the detection of organophosphorus pesticides: A non-enzymatic inhibition approach coupled with nano-scale electrode engineering to improve electrode sensitivity
    (ELSEVIER SCIENCE SA, 2018) Tunesi, Mawada Mohamed; Kalwar, Nazar; Abbas, Malik Waseem; Karakus, Selcan; Soomro, Razium Ali; Kilislioglu, Ayben; Abro, Muhammad Ishaq
    This study explores the potential of a newly-developed indium tin oxide (ITO) based electrode for the development of an electro-catalytic inhibition sensor system for organophosphorus pesticides. The sensor relies on the redox signal inhibition of pralidoxime chloride (PAM) immobilised over the pimelic acid functionalised CuO nanostructures grown in-situ over an ITO substrate. The in-situ growth enabled on-pot modification and functionalisation of ITO electrodes with the formation of uniform nanostructures possessing high surface area and excellent interface contact. The versatility of the proposed electrode was evident from its excellent electrochemical characteristics evaluated in comparison to bare and slurry-driven glassy carbon electrodes (GCEs). The high structural uniformity and greater surface coverage achieved by in-situ growth provided a uniform surface environment for electrode-analyte interaction, leading to good inhibition signal sensitivity and repeatability. The developed sensor was successful in detecting chlorpyrifos, fenthion and methyl parathion within the concentration range of 0.01-0.16 mu M with signal sensitivity reaching down to 1.6 x 10(-9), 2.5 x 10(-9) and 6.7 x 10(-9) M respectively. Moreover, the proposed sensor demonstrated excellent applicability when tested for chlorpyrifos from vegetable extracts using a standard addition method. (c) 2018 Elsevier B.V. All rights reserved.
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    Tartaric acid assisted in-situ growth of CuO nanostructures over ITO substrate for the electrocatalytic detection of Sudan I
    (ELSEVIER SCI LTD, 2018) Tunesi, Mawada Mohamed; Kalwar, Nazar Hussain; Soomro, Razium Ali; Karakus, Selcan; Jawaid, Sana; Abro, Muhammad Ishaq
    The study explores the potential of newly developed ITO based electrode for the electro-catalytic detection of Sudan I. The ITO based electrode utilizes a dense layer of 2D CuO nanostructures as an effective electron-transfer facilitator which promotes the electro-catalytic sensing of Sudan I in aqueous solution. The in-situ growth of CuO nanostructures was achieved using simple hydrothermal route with the assistance of tartaric acid utilized as an effective template. The in-situ grown layer comprises of 2D CuO nanostructures with morphological features similar to flowers composed of sharp-flake like features. The electro-catalytic oxidation of Sudan I over the described electrode system demonstrated low-over potential value and excellent working stability with good analytical linearity in the range of 0.001-1.56 mu M. The ITO based electrode was found highly selective and sensitive towards Sudan I with limit of detection determined to be 1.2 x 10(-4) mu M (S/N = 3).