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 (WO 3 -RGO) nanocomposite as a matrix. The in-situ hydrothermal method was employed for the synthesis of the WO 3 -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 WO 3 -RGO nanocomposite was further functionalized with 3-aminopropyl tri-ethoxy saline (APTES) for the activation of amino groups (‒NH 2 ) 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 WO 3 nanorods has allowed the immunosensor to exhibit enhanced heterogeneous electron transfer rate constant (K o  = 2.4 × 10 −4 cms -1 ) resulting in improved biosensor efficiency. The immuno-sensor exhibit good sensitivity as 58.24 μA/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. [ABSTRACT FROM AUTHOR]