Uda Hashim
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Uda Hashim
Official Name
Uda, Hashim
Alternative Name
Hashimb, U.
Hashim, Uda
Hashim, U.
Uda, Hashim
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Scopus Author ID
22633937800
Researcher ID
CVC-6955-2022

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  • Publication
    A Point-of-Care immunosensor for human chorionic gonadotropin in clinical urine samples using a cuneated polysilicon nanogap Lab-on-Chip
    ( 2015)
    S. R. Balakrishnan
    ;
    Uda Hashim
    ;
    Subash Chandra Bose Gopinath
    ;
    Prabakaran A/L Poopalan
    ;
    H. R. Ramayya
    ;
    M. Iqbal Omar
    ;
    R. Haarindraprasad
    ;
    P. Veeradasan
    Human chorionic gonadotropin (hCG), a glycoprotein hormone secreted from the placenta, is a key molecule that indicates pregnancy. Here, we have designed a cost-effective, label-free, in situ point-of-care (POC) immunosensor to estimate hCG using a cuneated 25 nm polysilicon nanogap electrode. A tiny chip with the dimensions of 20.5 × 12.5 mm was fabricated using conventional lithography and size expansion techniques. Furthermore, the sensing surface was functionalized by (3-aminopropyl)triethoxysilane and quantitatively measured the variations in hCG levels from clinically obtained human urine samples. The dielectric properties of the present sensor are shown with a capacitance above 40 nF for samples from pregnant women; it was lower with samples from non-pregnant women. Furthermore, it has been proven that our sensor has a wide linear range of detection, as a sensitivity of 835.88 μA mIU-1 ml-2 cm-2 was attained, and the detection limit was 0.28 mIU/ml (27.78 pg/ml). The dissociation constant Kd of the specific antigen binding to the anti-hCG was calculated as 2.23 ± 0.66 mIU, and the maximum number of binding sites per antigen was Bmax = 22.54 ± 1.46 mIU. The sensing system shown here, with a narrow nanogap, is suitable for high-throughput POC diagnosis, and a single injection can obtain triplicate data or parallel analyses of different targets.