Optical biosensors for rapid profiling of SARS-CoV2 binding and neutralizing antibodies in dried blood spot samples

Precise monitoring of SARS-CoV2 neutralizing (NAbs) is of great importance for evaluating the vaccines safety and investigating the dynamics of immune response and epidemiology of COVID-19. Current mainstream diagnostic methods for SARS-CoV2 NAbs requires strict biosafety level-3 operating environment, which is time- and labor-consuming, and requires regular venous sampling for blood collection, which is invasive and harmful for intensive sampling and large-scale immunological and epidemiologic investigation. Bio-layer interferometry (BLI) technique (Fig. 7A), integrated with dried blood spot (DBS) self-sampling [FDA2020, J Pharm Biomed Anal 2020], enables us to establish a rapid optical biosensor for monitoring of SARS-CoV2 NAbs in whole blood in a less strict operating environment. BLI technique is a powerful tool for identifying the interaction between antibodies and proteins, but its use for sensitive quantification is challenging due to its rather limited signal readout, specifically for low target concentration. The use of an appropriate enhancer, being a bio-enhancer or a nano-enhancer, can solve this issue and results in effective signal amplification. At CenBRAIN, we are currently able to detect SARS-CoV2 NAbs within 7.5 min with sufficient clinical validity and utility [Fig. 7B], as validated by using a batch of human sera from healthy volunteers who recently received the local vaccines. In addition, this method has been well applied for detection of SARS-CoV2 IgG binding antibodies (BAbs) against RBD or full spike protein within 13 min. In the next step, we will evaluate the feasibility of using dried blood spots as an easy and alternative sample matric, to replace the regular venous blood for both SARS-CoV2 NAbs and BAbs rapid detection. Related Publications: FDA2020, J Pharm Biomed Anal 2020
Figure 7. Brief introduction of the automated optical Octet K2 device at CenBRAIN and the detection process for SARS-CoV2 NAbs detection in human serum with a sample-to-result time of 7.5 min.