Rapid and quantitative detection of SARS-CoV-2 IgG antibody in serum using optofluidic point-of-care testing fluorescence biosensor.

The COVID-19 pandemic brings unprecedented crisis for public health and economics in the world. Detecting specific antibodies to SARS-CoV-2 is a powerful supplement for the diagnosis of COVID-19 and is important for epidemiological studies and vaccine validations. Herein, a rapid and quantitative detection method of anti-SARS-CoV-2 IgG antibody was built based on the optofluidic point-of-care testing fluorescence biosensor. Without complicated steps needed, the portable system is suitable for on-site sensitive determination of anti-SARS-CoV-2 IgG antibody in serum. Under the optimal conditions, the whole detection procedure is about 25 min with a detection limit of 12.5 ng/mL that can well meet the diagnostic requirements. The method was not obviously affected by IgM and serum matrix and demonstrated to have good stability and reliability in real sample analysis. Compared to ELISA test results, the proposed method exhibits several advantages including wider measurement range and easier operation. The method provides a universal platform for rapid and quantitative analysis of other related biomarkers, which is of significance for the prevention and control of COVID-19 pandemic.