Ultrasensitive detection of miRNA-155 using multi-walled carbon nanotube-gold nanocomposites as a novel fluorescence quenching platform

Multi-walled carbon nanotube-gold nanocomposites (MWCNT/AuNCs) were prepared and used as a novel fluorescence quenching platform for ultrasensitive detection of miRNA-155. In the designed system, fluorophore labeled DNA probe was introduced, and the fluorescence signal of them were effectively quenched due to the adsorption of them on MWCNT/AuNCs. Upon the addition of target miRNA-155, DNA-RNA heteroduplexes were formed and desorbed from MWCNT/AuNCs to yield a strong fluorescence signal. In the presence of duplex-specific nuclease (DSN), DNA-RNA heteroduplexes became a substrate for the enzymatic hydrolysis of DNA strands and triggered cyclic signal amplification. Under optimal conditions, MWCNT/AuNCs displayed 93.2% of the quenching efficiency to the fluorophore labeled DNA probe, paving the way for ultrasensitive miRNA-155 detection with a detection limit down to 33.4 fM. Meantime, the present strategy showed excellent selectivity for miRNA-155 detection against other miRNAs including miRNA-21, miRNA-141, and mutated miRNA-155 strands. Moreover, satisfactory results were obtained for miRNA-155 detection in human serum samples, illustrating that the proposed sensing platform is applicable in disease diagnosis.