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 (MB30) and 1000 nm-magnetic particles (MM1000) linked by single-strand RNA1 complexes (MB30-RNA1- MM1000) 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 MB30-RNA1-MM1000, releasing MB30 which caused transverse relaxation time (T2) 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.
Keywords: CRISPR/Cas13a; Magnetic relaxation switching; Signal amplification; miRNA.
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