FADH2-mediated radical polymerization amplification for microRNA-21 detection

For early diagnosis of disease, ultrasensitive mircoRNA-21 detection has considerable potential. In this paper, an ultra-sensitive fluorescence detection method for microRNA was developed by atom transfer radical polymerization (ATRP). This ATRP reaction was first initiated by using flavin mononucleotide (FADH2). The DNA probe 1 modified with amino group was fixed on the magnetic nanoparticle Fe3O4, and microRNA-21 was added to form the probe 1-microRNA-21. Another carboxy-modified DNA 2 forms a sandwich structure with the bound microRNA-21. Two terminally modified DNA types are used as microRNA probes, using complementary base pairing to form a stable super-sandwich structure between the DNA probe and the microRNA. Under optimal conditions, microRNA was detected in PBS buffer with a detection limit of 0.19 fM. And even in 10% of human serum, microRNA-21 can be detected with a detection limit of 47.8 fM. Results show that this method has high selectivity, efficiency and stability, which broad application prospect in microRNA ultra-sensitive detection.