Ultra-sensitive impedimetric biosensor for HCV detection in patient samples coupled with double-noble nanoparticles on carbon ink-patterned paper electrode.

An ultra-sensitive impedimetric paper-based biosensor for the rapid detection of hepatitis C virus (HCV) core antigen in human serum, integrating double-noble Silver–AuNPs onto a carbon ink-patterned paper electrode is presented. The sensing interface is developed by immobilizing anti-HCV core antibodies onto a silver–gold nanoparticle (Ag–AuNP)-modified electrode surface, which serves as the biorecognition layer. This configuration enables label-free detection of antigen–antibody interactions using electrochemical impedance spectroscopy (EIS). Sensor performance was systematically optimized with respect to antigen concentration (0.1 ng/mL–500 µg/mL), incubation temperature, reaction time, and operational stability under repeated measurements. The optimized platform achieved a low limit of detection of 10.21 ng/mL and a limit of quantification of 34.05 ng/mL, with a wide linear dynamic range suitable for clinically relevant HCV core antigen levels. Analytical validation using HCV-positive clinical serum samples demonstrated high diagnostic accuracy and specificity against non-HCV samples. The proposed Silver–AuNPs based impedimetric immunosensor offers a low-cost, portable, and time-efficient alternative to conventional laboratory assays, with strong potential for point-of-care screening and large-scale surveillance of HCV infection, particularly in resource-limited settings.