CRISPR/Cas13a-based colorimetric biosensing platform for point-of-care detection of viral nucleic acids

Rapid and accurate diagnosis is important in preventing and effectively combating infectious disease outbreaks. The CRISPR/Cas13a-based Specific High-sensitivity Enzymatic Reporter UnLOCKing (SHERLOCK) platform possesses the advantages of high efficiency, good specificity and sensitivity, and it has been widely adopted in molecular diagnostics. However, the traditional SHERLOCK platform requires dual-labeled RNA probes for fluorescence detection or lateral flow assay, which entail tedious modification procedures and sophisticated optical instruments, limiting its broad applications. Herein, we developed a rapid, sensitive, and label-free point-of-care (POC) platform for colorimetric assays of dengue virus (DV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with the SHERLOCK method. The adoption of the SHERLOCK-mediated guanine-quadruplex (G4)/hemin DNAzyme-based colorimetric strategy produced cascade signal amplification detection with improved analytical performance. Moreover, it exhibited high sensitivity and specificity for detection in cell-cultured DV samples, and DV and SARS-CoV-2 clinical samples, as well as accurate identification of the four DV serotypes. Hence, the proposed colorimetric biosensing platform has great potential for rapid, accurate, and specific POC detection of viral infections in field-deployable assay.