Cost-effective Biosensor for SARS-CoV-2 Detection Using Zinc Oxide Nanorods and Gold Nanoparticles Functionalized with RBD Antibodies.

Electrochemical biosensors offer a cost-effective alternative for point-of-care diagnostics. Zinc oxide nanorods (ZnONRs) are promising materials for biosensor development due to their favorable physicochemical properties, which provide a suitable microenvironment for biomolecule adsorption. Monoclonal antibodies conjugated with gold nanoparticles (AuNPs) can further enhance biosensor performance by combining the unique properties of AuNPs with the specific selectivity of antibodies. This study proposes a biosensor based on ZnONRs functionalized with anti-RBD antibodies conjugated with AuNPs for the detection of SARS-CoV-2 in saliva samples. Among the four monoclonal antibodies tested (C1, C2, C3, and C4), C3 demonstrated the best electrochemical performance. The cost of the biosensor was estimated at $7.60, with a test response time of 6 minutes. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to characterize the biosensor, and the detection limit was found to be 1.7 μg mL⁻¹, highlighting the potential of these materials for the development of a simple, rapid, and accessible diagnostic method.