Speedy, Specific, Synchronous Sensing Platforms with Ruthenium Complexes for Multiplexed MicroRNA Detection

Inspired by our previous study on Ru­(II)-based compounds for the construction of a sensing platform toward detection of microRNA-185 (miR-185), we herein report new analytical platforms based on two additional Ru­(II) compounds, Ru 2 and Ru 3, with larger aromatic ring structures and richer hydrogen bond donor/acceptor sites in comparison to the previously reported Ru 1, as simultaneous detection agents for miR-221/222, which work together to promote the occurrence and development of breast cancer. Molecular simulation docking was first used to predict the nucleic acid sequence binding affinity toward Ru­(II) compounds to guide the experiment. The experimental results reveal that Ru 2 and Ru 3 can form a P-DNA@Ru sensing platform with the introduction of carboxyfluorescein (FAM)/5-carboxy-X-rhodamine (ROX) tagged single-chained probe DNA (P-DNA), to realize the discernment of the complementary P-DNA sequence of miR-221/222, giving the limit of detection (LOD) at the nanomolar level with a specific and speedy response. The detection mechanism was verified by binding capacity, luminescence decay, and fluorescence anisotropy (FA), as well as the polyacrylamide gel electrophoresis (PAGE) technique. Furthermore, the formed P-DNA@Ru 2/3 systems could be prepared for the simultaneous and synchronous detection of miR-221/222 sequences, improving the detection efficiency in a time-efficient manner and satisfying the speedy diagnosis requirements of current medical practive.