The assessment of interaction kinetics between specific monoclonal antibody and immobilized SARS-CoV-2 nucleoprotein

The emergence of SARS-CoV-2 has posed significant global health challenges. The nucleocapsid protein (N-protein) is a structural part of the SARS-CoV-2 virus and an important immunogenic target of specific antibodies, which are developed in the organism during the infection by this virus. Artificially designed specific (monoclonal and polyclonal) antibodies are also used for therapeutic and bioanalytical purposes, therefore, the assessment and characterization of newly designed antibodies is an important analytical issue. This study reports an electrochemical biosensing system for the assessment of the interaction between newly designed specific antibody and SARS-CoV-2 recombinant N-protein, against which the antibody was designed, and which was used as a target in biological recognition part of the biosensing system. The biosensing system was applied for the determination of the interaction kinetics between immobilized N-protein and a newly derived monoclonal antibody (mAb) 16D9 (mAb-16D9). Cyclic voltammetry was employed to evaluate the kinetics of the interaction between the recombinant N-protein and mAb-16D9. The binding constant (Kc) was determined to be 50.99 μg/mL, demonstrating a strong affinity, while the limit of detection was 4.3 × 10⁻⁴ μg/mL, highlighting sufficient affinity of mAb-16D9 towards N-protein, which determined good sensitivity of the developed biosensors. These findings highlight the potential application of the here-reported electrochemical biosensor for rapid testing of antigen-antibody interaction kinetics and the characterization of newly designed antibody.