Impedance-Based Neutralizing Antibody Detection Biosensor with Application in SARS-CoV-2 Infection

Although safe and efficacious coronavirus disease 2019 (COVID-19) vaccines are available, real protective immunity is revealed by the serum COVID-19 neutralizing antibody (NAb) concentration. NAbs deactivate the virus by attaching to the viral receptor-binding domain (RBD), which interacts with angiotensinconverting enzyme 2 (ACE2) on the human cell. This paper introduces inexpensive, rapid, sensitive, and quantifiable impedance-based immunosensors to evaluate the NAb. The sensor limit of detection is experimentally determined in different buffer dilutions using bovine IgG-anti-bovine IgG interaction. The dominance of AC electrokinetic transport and molecular diffusion in the sensor is investigated using scaling analysis and numerical simulations. The results demonstrated that the sensor detection mechanism is mainly based on the diffusion of the biomolecules onto the electrode surface. After evaluating the sensor working principles, viral RBD buffers, including different NAb concentrations, are applied to the sensor, immobilized with the human ACE2 (hACE2). Results demonstrate that the sensor is capable of NAb detection in the analytical measuring interval between 45 ng/mL and 185 ng/mL. Since the present sensor provides fast test results with lower costs, it can be used to assess the NAb in people's blood serum before receiving further COVID vaccine doses.

Automated summary

This study introduces inexpensive, rapid, sensitive, and quantifiable impedance-based immunosensors to evaluate the concentration of neutralizing antibodies (NAb) against the coronavirus. The sensor detection mechanism is mainly based on the diffusion of biomolecules onto the electrode surface. The results demonstrate that the sensor is capable of detecting NAb in the range of 45 ng/mL to 185 ng/mL. Due to its fast test results and lower costs, this sensor can be used to assess NAb in people's blood serum before receiving further COVID vaccine doses.