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 30 ) and 1000 nm-magnetic particles (MM 1000 ) linked by single-strand RNA 1 complexes (MB 30 -RNA 1 - MM 1000 ) 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 30 -RNA 1 -MM 1000 , releasing MB 30 which caused transverse relaxation time (T 2 ) 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.