A homogeneous fluorescence sensing platform with water-soluble carbon nanoparticles for detection of microRNA and nuclease activity

Based on the high efficiency of fluorescence quenching and the different affinities of water-soluble carbon nanoparticles (CNPs) towards single-stranded DNA (ssDNA) and double-stranded DNA/RNA hybrid, a novel, rapid and cost-effective assay for detection of microRNA and nuclease activity was developed. The fluorescein-labeled ssDNA probe (FAM-P) could be adsorbed on the surface of CNPs through π-π stacking interaction giving rise to fluorescence quenching. By introduction of microRNA complementary to the DNA probe, the double-stranded DNA/miRNA hybrid could be formed and released from the surface of CNPs resulting in the fluorescence recovery. Thus, microRNA was successfully detected in homogenous fashion without any amplification or enzyme-involving reactions. Moreover, we demonstrated that the nuclease activities of RNase H and DNase I could also be sensitively monitored by using CNPs based on the fluorescence changing of the DNA probe. So, the CNPs provide an excellent homogeneous sensing platform for studying molecular diagnosis and therapeutics.