Fluorescent oligonucleotide indicators for ratiometric microRNA sensing on metal-organic frameworks

Two kinds of Luminescent metal organic framework (LMOF) based probes were developed as fluorescent oligonucleotide indicators for ratio-metric microRNA (miRNA) sensing. One LMOF (AuNCs@ZIF-8) is ZIF-8 encapsulated with gold nanoclusters (AuNCs). Another LMOF (Zn(2)Ph(2)Da) is prepared by using 2, 2'-dithiodi-benzoic acid (dtba) and 1, 10-phenanthroline (phen) as ligands, and Zn2+ as metal center. Both of them possess fluorescence emission behavior and fluorescence quenching ability toward adsorbed fluorophore labeled miRNA aptamers. When target miRNAs hybridize with aptamers, the fluorescence of labeled fluorophores would recover. Meanwhile, the fluorescence intensity of LMOFs keeps unchanged. For enhancing miRNA detection sensitivity, novel fluorophore-labeled aptamers (SYBR-dsDNA-Aps) composed of miRNA aptamers and dsDNA fragments embedded with SYBR Green I molecules were designed and optimized. The detection of miR-21 and miR-155 in the blood serum of breast cancer bearing mice or inflammatory rats prove that prepared fluorescent oligonucleotide indicators could be promising choices for ratiometric miRNA sensing.