CRISPR-Cas-based colorimetric strategies for nucleic acids detection

Accurate and facile detection of nucleic acids is significant for diagnosis and prognosis of diseases. Compared with traditional methods, CRISPR-based diagnosis shows high sensitivity and specificity, hopefully becoming the next-generation molecular diagnosis approach. Various signal output modes have been integrated with CRISPR-Cas to achieve ultrasensitive detection of nucleic acid biomarkers. Among these signal modes, colorimetric signal attracts great attention due to its simplicity, which will contribute to the point-of-care testing of nucleic acid biomarkers. Therefore, different CRISPR-based colorimetric strategies have been designed, aiming to realize facile and ultrasensitive nucleic acid biomarkers detection. In this review, the working mechanism of four CRISPR-Cas systems is first introduced, followed by summarizing the research progress of CRISPR-Cas-based colorimetric strategies, including UV/blue light-based colorimetry, lateral flow strip-based colorimetry, AuNPs-based colorimetry in solution and enzyme-based colorimetry. Furthermore, the challenges and perspectives in this field are discussed to promote the development of CRISPR-Cas-based colorimetry in practical application.