An integrated signal amplification strategy based on catalytic hairpin assembly and hybridization chain reaction for driving a CRISPR/Cas12a biosensor toward ultrasensitive detection of microRNAs.

A novel biosensing platform is proposed that integrates catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) cascade isothermal amplification with the CRISPR/Cas12a system, enabling ultrasensitive detection of microRNAs (miRNAs) targets. Within this platform, two modules are integrated: a target recognition and signal amplification module constructed by the cascade of CHA and HCR, and a signal transduction module in which the CRISPR/Cas12a system acts in concert with DNA probes loaded onto gold nanoparticles (AuNPs). This design achieves cascaded amplification from target recognition to signal output, thereby conferring high signal gain. Experimental results demonstrate that the proposed biosensor had high sensitivity toward the target miRNA, with a detection limit as low as 37 fM. Moreover, it shows remarkable single-base discrimination capability, effectively distinguishing sequences with single-nucleotide mismatches. Notably, the sensor maintains stable and reliable performance in complex biological matrices, including serum samples and lysates from various tumor cells. This strategy effectively couples signal amplification with the CRISPR system, achieving both high sensitivity and specificity, making it a useful tool for miRNA detection and early cancer screening.