CoOOH nanoflake as supporter of CRISPR-Cas12a system for facilitated imaging of miRNA-21 in cells

The aberrant expression of miRNA-21 in cells is frequently associated with the occurrence and metastasis of tumors. The CRISPR-cas12a system has been developed for in vitro detection of miRNA due to its distinctive signal amplification characteristics. But its intricate composition and challenges in cellular delivery have limited its application in cell imaging. In this study, we designed an electrostatic adsorption-based probe by combining positively charged cobalt hydroxyl oxide (CoOOH) nanoflakes with negatively charged CRISPR-cas12a system which allows for detection and intracellular imaging of miRNA-21. This method involves using ascorbic acid to reduce CoOOH nanoflakes into Co²⁺, which subsequently releases the active form of CRISPR-Cas12 for detecting miRNA-21. The probe has a linear detection range for miRNA-21 from 0.5 pM-50 pM and 100 pM-20 nM, with a detection limit of 0.32 pM. It also shows good selectivity, accuracy, good reproducibility and biocompatibility for miRNA-21 analysis. In subsequent cell experiments, the probe exhibits low cytotoxicity and remarkable cell imaging capabilities. Therefore, this probe offers an innovative approach for miRNA-21 analysis.