Label-free Immunosensor Based on a One-Step CTAB Intercalated Graphene Nanocomposite for Hepatitis C Virus Detection

A new label-free immunosensor containing cetyltrimethylammonium bromide (CTAB) intercalated-graphene oxide (GO) on a polythiophene (PTh) film one-step electrosynthetized is described for detection of hepatitis C antibodies (Anti-HCV). This electroactive film also acted as a substrate for immobilizing the biorecognition element. The ability of the biosensor to bind Anti-HCV was monitored by the square wave voltammetry (SWV) technique through the decrease in anodic peaks. The intercalation of GO nanosheets between CTAB and PTh was very stable, achieving a variation coefficient of approximately 0.65% for redox peaks after 30 cycles, and was also demonstrated as a diffusion-controlled process with excellent electrochemical reversibility. The immunosensor exhibited a linear response range from 0.2 to 8 ng∙mL−1, good reproducibility (square R equal to 0.993, low relative error < 1%), and a limit of detection at 0.07 ng∙mL−1 of Anti-HCV, achieving the clinical range for HCV diagnostic. Furthermore, this approach shows promise for constructing a practical and accurate immunosensor for HCV diagnostic and screening in chronic phases and monitoring other HCV biomarkers utilizing this technology.