Ultra-sensitive aptasensor based on a GQD nanocomposite for detection of hepatitis C virus core antigen

In the present study, by using the aptamer proximity binding assay strategy, a novel electrochemical aptasensor is described for ultrasensitive detection of hepatitis C virus (HCV) core antigen. The immobilization surface is prepared by the modification of a glassy carbon electrode (GCE) with a graphene quantum dots (GQD). GQD were introduced as a novel and suitable substrate for aptamers through π-π stacking interactions, the richness of hydrophilic edges as well as hydrophobic plane in GQD which enhances the aptamer absorption on the electrode surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed at each stage of the chemical modification process to confirm the resulting surface changes. EIS technique was used as an efficient alternative detection system for HCV core antigen measurement with detection limit 3.3 pg mL^-1 and two linear concentration range 10-70 pg mL^-1 and 70-400 pg mL^-1. Moreover, the fabricated aptasensor could accurately detect HCV core antigen concentration in human serum samples. Such an aptasensor opens a rapid, selective and sensitive route for HCV core antigen detection and provides a promising strategy for potential applications in clinical diagnostics.