A sensitive and specific method for microRNA detection and in situ imaging based on a CRISPR–Cas9 modified catalytic hairpin assembly

We report here a method for the molecular detection of miRNAs in exosomes and imaging in living cells based on CRISPR-Cas9 and catalytic hairpin assembly. With the cascade signal amplification of catalytic hairpin assembly and high specific recognition of CRISPR-Cas9, the detection method showed a sensitivity of 23.5 fM and was applied for accurate exosomal miR-21 detection and in situ miR-21 imaging.