Graphene Oxide based Label Free Ultrasensitive Immunosensor for Lung Cancer Biomarker, hTERT

摘要

We report the fabrication of ultrasensitive Graphene Oxide (GO) based electrochemical immunosensor to detect human telomerase reverse transcriptase (hTERT), a lung cancer biomarker. The immuno-electrode-has been fabricated by covalent immobilization of rabbit anti-hTERT antibodies (Ab) onto GO films on ITO coated glass. The Fourier Transform Infrared (FTIR) spectroscopic studies confirms the presence of diverse organic functional groups (-COOH, -CHO, -OH) of GO, and the binding (anti-hTERT) onto GO/ITO electrode. Interestingly, Scanning Electron Micrographs (SEM) also reveals clear visual surface modification of the GO film by anti-hTERT antibodies and hTERT antigen (Ag). The electrochemical Differential Pulse Voltammetry (DPV) results show that the GO based immunosensor exhibits specificity and low detection upto 10 ag mL-1 (10×10-18 g mL-1) in wide detection range (10 ag mL-1-50 ng mL-1) for hTERT. The immunosensor showed ability to detect hTERT in spiked sputum samples upto 100 fg mL-1 in dynamic detection range of 100 fg mL-1-10 ng mL-1. The enhanced performance of Ab/GO/ITO is attributed to fast electron transfer and efficient loading of Ab on large surface area provided by GO network. The low level detection of hTERT warrants the realization of point-of-care device for early detection of lung/oral cancer through oral fluids.