S. Wang, Y. Zhou, Z. Li
The George Washington University,
Keywords: microfluidic, lab-on-a-chip, automation, immunoassay, point-of-care diagnostics
Summary:Immunoassays, such as enzyme immunoassay (EIA), radioimmunoassay (RIA), fluoroimmunoassay (FIA), chemiluminescent immunoassay (CLIA), and counting immunoassay (CIA), are widely used in clinical diagnostics, drug discovery, drug monitoring, and food testing for their high sensitivity and specificity. The ability of quantitative detection of trace molecules makes them suitable for early-stage disease screening and confirmation, and recovery monitoring. However, most such high-sensitive immunoassays require long incubation time and extensive liquid handling. Some automation systems minimize the hands-on time and improve the sensitivity compared to traditional procedures. Nevertheless, the increased cost, bulky instruments and special reagents make them less desirable in point-of-care (POC) settings. In this work, we present a low-cost, injection moldable microfluidic cartridge that adopts the standard reagents and materials used in traditional immunoassays. The dynamic control of the reagent flow by precise pneumatic pressure and micro geometry maximizes the receptor-ligand binding efficiency thus reducing the incubation time and reagent volume needed to achieve equivalent or better sensitivity compared to traditional immunoassay kits. We demonstrate that the microfluidic cartridge enables automated high-sensitivity FIA. Human anti-SARS-CoV-2 antibody (IgG) could be detected under 30 minutes at the sensitivity comparable to commercial immunoassays. The hands-on time is less than 1 minute, which makes this method well-suited for POC settings.