Fig. 2

A hypothetical Cas13-based microfluidic biosensor for cancer diagnosis. First, the blood of NSCLC patients, containing materials derived from the tumor, enters directly into the entry well. After the isolation of the nucleic acids, they are followed into wells containing reagents for the detection of DNA mutations or quantifying overexpressed NSCLC-associated RNAs. Cas13 is activated by direct targeting of RNAs and subsequent matching of the target RNA sequence with the crRNA spacer sequences. This leads to cleavage of the target RNA and fluorescent reporter RNAs. On the other hand, after amplification of tumor DNAs with RPA, the T7 promoter sequence is added to the 5'-end of the RPA forward primer, and RPA amplicons are transcribed with T7. By binding to mutation-containing transcripts, Cas13 cleaves fluorescent reporter RNAs to provide the detectable signals