Since the first case of a novel coronavirus disease (COVID-19) in Wuhan, China at the end of 2019, the causative agent named severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) has been spreading around the world causing immense public health and socioeconomic problems. This tremendous spread of the COVID-19 is attributed to the fact that the disease can often be asymptomatic or its symptoms can be misinterpreted as due to the flu. To enable timely response and effectively prevent the virus transmission, frequent self-testing methods that can specifically identify SARS-CoV-2 by distinguishing from influenza viruses are needed. However, the current diagnostic methods (e.g., RT-qPCR) demands a bulky and expensive thermal cycler with a prolonged assay time and painstaking steps by trained technicians with sophisticated laboratory instruments, which limits their use in point-of-care (POC) settings. In this work, we report a fully-integrated POC toolkit for multiplex molecular diagnosis of SARS-CoV-2, influenza A and B viruses from saliva. The paper-based device was physically programmed with a built-in capillary flow regulation by creating integrated timers on flow paths. The sequential routing of the capillary flow on paper with controlled delays enables to run a sequence of chemical reactions and internally generate heat to drive those reactions to autonomously extract, amplify, and detect the viral RNA. Using our assay, we could identify SARS-CoV-2 and influenza A and B viruses at concentrations as low as 5 copies/μL visually from a colorimetric analysis. The capability to autonomously perform a traditionally labor-intensive genetic assay on a disposable platform will enable frequent, on demand self-testing, a critical need for POC testing to positively identify COVID-19 infections.

Multiplex and colorimetric assay of SARS-CoV-2, influenza A and B viruses using point-of-care toolkit

ACS Fall 2021

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