Rapid and Low-Cost Paper-Based Lateral Flow Assays for Detection of Liquid-Borne Pathogens

Abstract

At-home diagnostic tests are extremely useful for rural testing, providing point-of-care detection of harmful pathogens without requiring extensive time, effort, and money to bring the samples back to the lab bench. These tests, commonly called rapid antigen tests but more precisely under the category of lateral flow assays (LFAs), hold exciting potential for the future of accessible healthcare. The research presented in this document has focused on the development of a protocol for the detection of liquid-borne pathogens using paper microfluidics and a smartphone-based fluorescence microscope. This work was first published for the detection of norovirus from wastewater samples and achieved high sensitivity using the particulometry method, or the direct counting of immunoagglutination using anti-norovirus antibodies conjugated to fluorescent particles. This protocol was then further developed for the detection of SARS-CoV-2 from clinical mouthwash samples. Using the same samples, the next work explored a novel technique for indirect measurement of virus presence using the flow behavior of the liquid through the paper channel. Finally, in a progression from antibody-antigen immunoassays, the next project worked to detect perfluorooctanoic acid (PFOA) using the flow rate profile and pre-loaded reagents. With the potential of increasing general education and accessibility of diagnostic healthcare, collectively these investigations contribute to the development of rapid and low-cost diagnostic tools for at-home and point of care use.