Rapid and quantitative detection of COVID-19 markers in micro-liter sized samples

Xiaotian Tan; Cory Lin; Jie Zhang; Maung Kyaw Khaing Oo; Xudong Fan

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.04. 20.052233 doi: bioRxiv preprint In this work, we present a microfluidic ELISA technology for rapid (15-20 minutes), quantitative, and sensitive detection of SARS-CoV-2 biomarkers using SARS-CoV-2 specific IgG and viral antigen -S protein, both of which are spiked in serum, as a model system. We also characterized various humanized monoclonal IgG and identified one with a high binding affinity towards SARS-CoV-2 S1 protein that can serve as the calibration standard of anti-SARS-CoV-2 S1 IgG in serological analyses. Furthermore, we demonstrated that our microfluidic ELISA platform can be used for rapid affinity evaluation of monoclonal anti-S1 antibodies. The microfluidic ELISA device is highly portable and requires only 10 L of samples for each channel, which can be easily collected from a drop of fingertip blood. Therefore, our technology will greatly facilitate rapid and quantitative analysis of COVID-19 patients and vaccine recipients at point-ofcare.