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  • Küçük Resim
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    Enzyme-free colorimetric sensing of glucose using L-cysteine functionalized silver nanoparticles
    (SPRINGER INTERNATIONAL PUBLISHING AG, 2019) Adnan, Sumaira; Kalwar, Nazar Hussain; Abbas, Malik Waseem; Soomro, Razium Ali; Saand, Mumtaz Ali; Awan, Fazli Rabbi; Avcı, Ahmet; Pehlivan, Erol; Bajwa, Sadia
    The study demonstrates an efficient, simple and on-site viable approach for sensitive determination of blood glucose using colorimetric sensing approach. The devised colorimetric sensor works based on cysteine functionalized silver nanoparticles. The as-synthesized Ag NPs were elaborately characterized using advanced analytical techniques such as ultra-violet visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy and X-ray diffraction. The detection of glucose was carried under ambient air conditions where change in the optical characteristics of Ag NPs and subsequent interaction between glucose and functional moiety (i.e. surface bind cysteine) of Ag NPs was considered as the signal response. This interaction led to direct detection of glucose in the concentration range between 0.01 to 0.17 mu M with limit of detection up to 1 x 10(-4) mu M. It is worthwhile mentioning that success of the assay lies in application of the developed colorimetric sensor in real blood glucose measurements, which also proved its capability for field based analysis. In addition its simple design, low cost, and more reliability signifies the usefulness of colorimetric sensor and it can be extended monitor other biologically important molecules.
  • Küçük Resim Yok
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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.