Rapid and Inexpensive point-of-use (POU) testing for SARS-CoV-2 quantification with membrane-based in-gel loop-mediated isothermal amplification (mgLAMP) system

Abstract

The quantification of SARS-CoV-2 in wastewater affords the ability to monitor the prevalence of infections among the population and provide early detection of contamination via wastewater-based epidemiol. (WBE). But widespread WBE for SARS-CoV-2 quantification would rely on the availability of specialized equipment and personnel for environmental (i.e., wastewater) sample prepn., processing, and anal. that are currently prioritized to meet the demand for clin. samples analyses. Here we demonstrated the usage of our portable membrane-based in-gel loop-mediated isothermal amplification (mgLAMP) system for abs. quantification of SARS-CoV-2 in wastewater samples within a 1h-timeframe for point-of-use (POU) testing and data management, which was compared with the performance of golden std. reverse-transcription quant. polymerase chain reaction (RT-qPCR) method. The limit of detection (LOD) of mgLAMP for SARS-CoV-2 quantification in Milli-Q water was obsd. to be down to 1 copies/mL, and that in surface water collected from Kathmandu, Nepal was down to 50 copies/mL. Both were 100-fold lower than that of RT-qPCR in corresponding matrixes. A 3D-printed portable device integrating incubation and illumination was manufd. to simultaneously allow the POU operation and anal. of 9 mgLAMP assays. Quant. result of the virus concn. can be sent back to a smart phone or stored in an online database. Compared to alternative detection methods, our platform has a very high level of tolerance against inhibitors due to the restriction effect of the hydrogel matrix, which allows for the highly sensitive detection in either clin. samples or environmental samples. Addnl. merits of our detection platforms are portability, cost-effectiveness, user-friendliness and versatility, allowing for water environmental and clin. POU testing applications in low-resource settings.