Hand-powered centrifugal micropipette-tip with distance-based quantification for on-site testing of SARS-CoV-2 virus.

This paper proposed a hand-powered centrifugal micropipette-tip strategy, termed HCM, for all-in-one immunoassay combined with a distance-based readout for portable quantitative detection of SARS-CoV-2. The target SARS-CoV-2 virus antigen triggers the binding of multiple monoclonal antibody-coated red latex nanobeads, forming larger complexes. Following incubation and centrifugation, the formed aggregated complexes settle at the bottom of the tip, while free red nanobeads remain suspended in the solution. The HCM enables sensitive (1 ng/mL) and reliable quantification of SARS-CoV-2 within 25 min. With the advantages of free washing, free fabrication, free instrument, and without the optical device, the proposed low-cost and easy-to-use HCM immunoassay shows great potential for quantitative POC diagnostics for SARS-CoV-2.