A simple and non-amplification platform for femtomolar DNA and microRNA detection by combining automatic gold nanoparticle enumeration with target-induced strand-displacement.

By combining the gold nanoparticle (AuNP) enumeration with target-induced strand-displacement reaction, we have developed a non-amplification platform for DNA and miRNA detection based on a deliberately designed sandwich-structured nanocomplex probe (SNC Probe). The proposed strategy can realize the sensitive detection of nucleic acids within 40min with the detection limit of 6.6 fM for HBV DNA and 13.5 fM for miRNA-141, respectively. The method presents reasonable ability to discriminate miRNA-141 from all the other members of miRNA-200 family. And it can also be used for direct detection of miRNA-141 in samples of extracted total small RNA from different cell lines which are reported to have altered levels of miRNA-141. Furthermore, the spike recovery (n = 3) of miRNA-141 in total small RNA extracts of Hela cells is found to be 92.8% for 20 p.M. and 94.7% for 100 p.M. with the standard deviation of 9.2% and 6.8%, respectively. As the only reagent involved in the assay, the SNC Probe presents a very good stability with a relative standard deviation of 3.3% amongst eight tests in 30 days, which greatly simplifies the assay procedure and presents the suitability for routine analyses. On the basis of these findings, this simple non-amplification assay platform can be expected to find assorted applications that can make the best use of the simplicity and sensitivity.