A label-free fluorescent enhancement nanosensor for ultrasensitive and highly selective detection of miRNA-378 through signal synergy amplification.

For early detection and diagnosis of gastric cancer, a novel, highly sensitive detection of microRNA-378 was developed through rolling circle amplification and DNA-templated silver nanoclusters as a lable-free fluorescent probe. DNA-templated fluorescent silver nanoclusters (DNA/AgNCs) to make target signal cascade amplification were prepared and identified through their fluorescent spectrum. MiRNA-378 trigged rolling circle amplification to obtain the complementary sequence (cDNA) to combine with two DNA/AgNCs in the middle of a sandwich structure to induce the new fluorescent signal at a new wavelength. In the presence of microRNA-378, a large amount of RCA product cDNAs were hybridized with DNA/AgNCs as the fluorescence nanocluster beacon, resulting in fluorescence enhanced "turn-on" phenomenon. This study indicated that amplified fluorescence detection of microRNA-378 is a stable, low-cost, highly specific, and ultra-low as 1.07 fM detectability. The proposed approach of signal synergetic amplification facilitating the fluorescence detection microRNA shows great potential for potentially clinically diagnosis.