A Prussian blue nanoparticles-based fluorescent nanoprobe for monitoring microRNA-92a and microRNA-21

Since microRNA-92a (miR-92a) and microRNA-21 (miR-21) are crucial biomarkers for colorectal cancer (CRC), monitoring miR-92a and miR-21 in serum is very significant for the early diagnosis of CRC. In this work, we developed a simple and sensitive fluorescent biosensor for the detection of miR-92a and miR-21 based on the quenching ability of Prussian blue nanoparticles (PBNPs) to fluorophores. Carboxyl fluorescein (FAM)-modified ssDNA (P-92a) and Cyanine 5 (Cy5)-modified ssDNA (P-21) were completely complementary to miR-92a and miR-21 separately. They were adsorbed on PBNPs surface by the binding of PO 4 3− in DNA and Fe 3+ in PBNPs to fabricate the P-92a + P-21@PBNPs sensing system. The fluorescence responses from P-92a + P-21@PBNPs show good selection to miR-92a and a great linear process with the miR-92a concentration ranging from 1 to 30 nM (Δ F = 10.978 c miR-92a + 71.457). Meanwhile, the fluorescence responses from P-92a + P-21@PBNPs is linearly relative to miR-21 from 3 to 30 nM; the linear equation is Δ F = 5.7560 c miR-21 + 48.729. Furthermore, the detections of miR-92a and miR-21 added in serum samples were achieved. In summary, this method is sensitive, highly specific, time-saving, cost-effective and applicable for the detection of miR-92a and miR-21. Therefore, this present sensor was expected to be used in clinical applications, which lays a potential foundation for an early diagnosis of cancer. Graphical abstract