CRISPR/Cas13a assisted amplification of magnetic relaxation switching sensing for accurate detection of miRNA-21 in human serum.

Development of rapid and accurate detection of miRNAs in complex samples is of great significance for potential early diagnosis of disease. Herein, we report a magnetic relaxation switching (MRS)-based strategy for direct detection of miRNAs in complex samples via the assistance of signal amplification system of CRISPR/Cas13a which has the ability to specifically recognize target RNA. In the designed strategy, 30 nm-magnetic nanoparticles (MB) and 1000 nm-magnetic particles (MM) linked by single-strand RNA complexes (MB-RNA- MM) were employed as signal probe. After the target miRNAs (taking miR-21 as model) recognition by CRISPR/Cas13a system, the resulted trans-cleavage degrades the MB-RNA-MM, releasing MB which caused transverse relaxation time (T) signal change. The combination of CRISPR/Cas13a assisted signal amplification and the MRS assay achieved direct detection of miR-21 in the serum sample without extracting within 60min, with a detection limit of 0.22 pM. Moreover, the detection accuracy is confirmed by performing the detection of miR-21 using qRT-PCR. The CRISPR/Cas13a system assisted MRS assay successfully achieved accurate, simple, and rapid detection of miRNAs in complex samples, showing great potential for detection miRNAs in potential clinical applications.