Fluorescence sensing platform based on ruthenium(II) complexes as high 3S (sensitivity, specificity, speed) and "on-off-on" sensors for the miR-185 detection.

Inspired by the enormous importance attributed to the biological function of miRNA, we pour our attention into the design and synthesis of four ruthenium(II) complexes and evaluate their applications as miR-185 detection agents by spectroscopic measurements. It was found that all complexes can form sensing platform for the detection of the complementary target miR-185 through the introduction of carboxyfluorescein (FAM) labeled single stranded DNA (P-DNA), giving the detection limits of 0.42nM for Ru 1, 0.28nM for Ru 2, 0.32nM for Ru 3, 0.85nM for Ru 4, all with instantaneous detection time in 1min. The results of the binding constant, fluorescence anisotropy (FA) and polyacrylamide gel electrophoresis experiments (PAGE) revealed that the ruthenium(II) complexes prefer to bind P-DNA other than hybrid duplexes DNA@RNA upon recognition, resulting in the detection of miR-185. These results provide useful suggestions in the new type of metal-based miRNA detection agents.