CRISPR/Cas12a-Enabled Amplification-Free Colorimetric Visual Sensing Strategy for Point-of-Care Diagnostics of Biomarkers.

CRISPR/Cas12a-based biosensors have garnered significant attention in the field of point-of-care testing (POCT), yet the majority of the CRISPR-based POCT methods employ fluorescent systems as report probes. Herein, we report a new CRISPR/Cas12a-enabled multicolor visual biosensing strategy for the rapid detection of disease biomarkers. The proposed assay provided vivid color responses to enhance the accuracy of visual detection. In the existence of the target, the -cleavage activity of CRISPR-Cas12a was activated. The report probe modified with magnetic beads (MBs) and horseradish peroxidase (HRP) was cleaved, and HRP was released in the supernatant. As a result, HRP mediated the etching of gold nanobipyramids (AuNBPs) under hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine and generated a vivid color response. The proposed method has been verified by the detection of the breast cancer 1 gene (BRCA1) as a proof-of-principle target. According to the different colors of AuNBPs, our experimental results have demonstrated that as low as 30 pM BRCA1 can be detected with no more than 60 min. Additionally, the proposed sensor has been successfully applied in the analysis of BRCA1 in human serum samples with satisfactory results, which indicates great potential for the sensitive determination of biomarkers and the POCT area.