BE-CATCH: Bioamplifier-Equipped CRISPR-Cas12a Transduction System Coupled with Commercial Pregnancy Test Strips to Harness Signal-on Point-of-Care Detection.

Repurposing existing commercial diagnostic equipment to enable portable analysis of diverse targets is driving the development of affordable point-of-care testing (POCT). Interestingly, we found that goat antimouse IgG could replace human chorionic gonadotropin (hCG) to make the T line of pregnancy test strips (PTS) appear red color and accordingly synthesized a novel signal output probe, which eliminated the intricate hCG covalent coupling steps, and could meet the multiple needs of expanded POCT. Given this, we introduced a novel separation-free universal POCT strategy termed bioamplifier-equipped CRISPR-Cas12a transduction system coupled with PTS to harness signal-on detection (BE-CATCH). Specifically, target inputs were converted and amplified by the multiplied strand displacement amplification-based bioamplifier, thereby activating Cas12a's trans-cleavage activity. Then, the activated Cas12a would cleave the connector indiscriminately, which ultimately kept the signal output probe in a free state; thus, the inputs could be translated into a colorimetric signal on the PTS. This strategy not only provided boosted sensitivity and specificity but also enhanced user-friendliness by maintaining the signal-on detection mode. We also demonstrated the versatility of the BE-CATCH strategy through selectively detecting miR-155 and flap endonuclease 1. Given its broad adaptability, the BE-CATCH strategy could provide an appealing option to broaden the application of PTS in biomedical diagnostics.