Biofunctionalized tungsten trioxide-reduced graphene oxide nanocomposites for sensitive electrochemical immunosensing of cardiac biomarker

We demonstrate the fabrication of a facile and efficient biosensing platform for electrochemical detection of human cardiac biomarker Troponin I (cTnI) using Tungsten trioxide-reduced graphene oxide (WO3-RGO) nanocomposite as a matrix. The in-situ hydrothermal method was employed for the synthesis of the WO3-RGO nanocomposite. Raman spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FE-SEM) were employed to investigate structural and morphological behavior. The WO3-RGO nanocomposite was further functionalized with 3-aminopropyl tri-ethoxy saline (APTES) for the activation of amino groups (-NH2) that can covalently bind to the antibodies of cTnI. This immunosensor was further studied using contact angle measurement, Fourier transform infrared spectroscopy (FT-IR) and electrochemical techniques. The synergistic behavior between RGO and WO3 nanorods has allowed the immunosensor to exhibit enhanced heterogeneous electron transfer rate constant (K-o = 2.4 x 10(-4) cms(-1)) resulting in improved biosensor efficiency. The immuno-sensor exhibit good sensitivity as 58.24 mu A/cm(2) per decade in an extended linear detection range 0.01-250 ng/mL with the stability up to 30 days. Besides this, the fabricated immuno-sensor exhibits good reproducibility and excellent selectivity towards the detection of the cTnI biomarker. Furthermore, the validation of immunosensor with cardiac patient samples demonstrates the clinical application of this nano-biosensing platform for the detection of other biomarkers too. (C) 2018 Published by Elsevier B.V.