A novel label-free electrochemical immunosensor based on AgNPs@Co(II)MOFs@PtNPs composite for the detection of rabies virus antibodies

Utilizing efficient diagnostic methods to assess antibody levels in unexposed individuals and vaccinated populations is of significant importance for the prevention and control of rabies virus (RV). In this study, we developed a novel label-free electrochemical immunosensor based on AgNPs@Co( II )MOFs@PtNPs composite materials for the rapid detection of RV antibodies. The RV nucleocapsid protein (NP) antigen and its nanobodies were firstly prepared using genetic engineering techniques as reagent materials. Next, a bimetallic composite of AgNPs@Co( II )MOFs@PtNPs was synthesized via a mixed solvothermal method, with cobalt-based metal-organic frameworks (Co-MOFs) serving as the substrate. This composite was deposited onto the surface of a glassy carbon electrode, where the RV-NP antigen was covalently attached to the Co-MOF surface, enabling specific binding with RV antibodies. The antigen-antibody interaction resulted in detectable changes in the current, facilitating the sensing process. Finally, the developed immunosensor exhibited a linear detection range for RV NP antibodies from 7.576 × 10 −11  mol/L to 3.788 × 10 −5  mol/L, with a correlation coefficient (R 2 ) of 0.9965 in differential pulse voltammetry, and the limit of detection was defined as 4.508 × 10 −10  mol/L. Furthermore, the newly immunosensor demonstrated excellent repeatability, stability, specificity, and clinical applicability, making it a promising, precise, and cost-effective tool for the early screening of RV antibodies.