CRISPR/Cas12a-based fluorescence biosensor for detection of exosomal miR-21 derived from lung cancer

Exosomes-derived miRNA-21 (miR-21) is intimately correlated with the lung cancer and can be used as a biomarker for early diagnosis of lung cancer. Due to the low abundance, high homology and complex matrix of miR-21 in the exosomes, accurate determination of exosomal miR-21 remains challenging. Combination of CRISPR technology with biosensors improves the detection specificity and sensitivity. This article reports a CRISPR/Cas12a-based fluorescence bioassay for the detection of exosomal miR-21 derived from lung cancer by coupling the state-of-the-art technologies including strand displacement reaction (SDR), terminal deoxynucleotidyl transferase (TdT), magnetic nanoparticles (MNPs). This biosensor exhibits high sensitivity (161 fM), and high specificity (against mismatched sequences) for the determination of miR-21. Furthermore, this method has been successfully used to detect the exosomal miR-21 in blood, and the results show that the biosensor is able to accurately distinguish cancer patients from healthy people. It is anticipated that the fabricated biosensor has great potentials for early diagnosis of lung cancer.