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 (Ko = 2.4 × 10−4 cms-1) resulting in improved biosensor efficiency. The immuno-sensor exhibit good sensitivity as 58.24 μA/cm2 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.