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Published March 28, 2023 | Supplemental Material + Submitted
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HCR Lateral Flow Assays for Amplified Instrument-Free At-Home SARS-CoV-2 Testing


The lateral flow assay format enables rapid, instrument-free, at-home testing for SARS-CoV-2. Due to the absence of signal amplification, this simplicity comes at a cost in sensitivity. Here, we enhance sensitivity by developing an amplified lateral flow assay that incorporates isothermal, enzyme-free signal amplification based on the mechanism of hybridization chain reaction (HCR). The simplicity of the user experience is maintained using a disposable 3-channel lateral flow device to automatically deliver reagents to the test region in three successive stages without user interaction. To perform a test, the user loads the sample, closes the device, and reads the result by eye after 60 minutes. Detecting gamma-irradiated SARS-CoV-2 virions in a mixture of saliva and extraction buffer, the current amplified HCR lateral flow assay achieves a limit of detection of 200 copies/μL using available antibodies to target the SARS-CoV-2 nucleocapsid protein. By comparison, five commercial unamplified lateral flow assays that use proprietary antibodies exhibit limits of detection of 500 copies/μL, 1000 copies/μL, 2000 copies/μL, 2000 copies/μL, and 20,000 copies/μL. By swapping out antibody probes to target different pathogens, amplified HCR lateral flow assays offer a platform for simple, rapid, and sensitive at-home testing for infectious disease. As an alternative to viral protein detection, we further introduce an HCR lateral flow assay for viral RNA detection.

Additional Information

The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. We thank M. Schwarzkopf and K. S. Lee for performing preliminary studies. We thank M. E. Bronner for reading a draft of the manuscript. We thank M. Schwarzkopf, K. S. Lee, L. M. Hochrein, G. Shin, B. J. Wold, and R. F. Ismagilov for helpful discussions. We thank G. Shin of the Molecular Technologies resource within the Beckman Institute at Caltech for providing HCR reagents. This work was funded by the Shurl and Kay Curci Foundation, by the Richard N. Merkin Institute for Translational Research at Caltech, by the National Aeronautics and Space Administration (Translational Research Institute for Space Health; NNX16AO69A), and by the National Institutes of Health (NIBIB R01EB006192 and NIGMS training grant GM008042 to S.J.S.). Competing Interest Statement. Patents, pending patent applications, and the startup company Molecular Instruments.

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Submitted - 20220918-508442v1full.pdf

Supplemental Material - media1.pdf

Supplemental Material - media2.mp4

Supplemental Material - media3.mp4


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October 9, 2023
December 22, 2023