CRISPR Cas12a-enabled biosensors coupled with commercial pregnancy test strips for the visible point-of-care testing of SARS-CoV-2

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has promoted the development of nucleic acid diagnosis technology. Several platforms with isothermal amplification methods have achieved sensitive and specific detection of SARS-CoV-2. However, they still suffer from complicated operations, delicate instruments, and unintuitive signal output modes. Here, a system consisting of CRISPR Cas12a-based biosensors and commercial pregnancy test strips (CRISPR-PTS) was established for the point-of-care testing of SARS-CoV-2. The target viral nucleic acids were finally reflected on the test strips through four steps, namely sample pretreatment, RT-RAA amplification, CRISPR Cas12a reaction, and separation-free hCG detection. This CRISPR-PTS assay possessed an outstanding sensitivity of as low as 1 copy per μL for SARS-CoV-2 detection and showed an excellent specificity in distinguishing the SARS-CoV-2 pseudovirus as well as other SARS-like viral clinical samples. In addition, the CRISPR-PTS assay performed well in practical applications, with 96.3% agreement versus RT-qPCR in spiked samples. With the advantages of low reagent cost, simple operation procedure, and visible signal output, CRISPR-PTS assay was expected to provide a strong supplement in the prevention and early diagnosis of infectious diseases in resource-limited situations.