Highly efficient fluorescence resonance energy transfer sensing of microRNA-155 at attomolar level with high specificity in cancer cells using carbon dots and MnO2 nanosheets as the energy donor-acceptor platform

MicroRNAs (miRNAs) are small non-coding RNAs of 18-25 nucleotides derived either from hairpin or double-stranded RNA precursors [1]. Sensitive, selective and rapid detection of microRNA in cell lines and biological fluids can provide critical information for clinical diagnosis and cancer treatment. Nanomaterial biosensors based on FRET phenomenon have the potential applications in research and clinical practice for DNA hybridization and tumor markers detection [2,3]. Here, fluorescence resonance energy transfer (FRET) sensing platform for sensitive detection of microRNA was developed using C-dots and MnO2 nanosheets as the energy donor-acceptor pairs. The C-dots with miRNA-155 probe, quenched with MnO2 nanosheets and restored fluorescence due to the strong affinity between probe and target miRNA-155. The fluorescence intensity possesses a logarithmic correlation to the miRNA-155 concentration in the two ranges from; 0.15 to 1.65 attomolar and from 1.65 to 20 attomaolr, respectively, and calculated detection limit was 0.1 attomolar. Furthermore, the presented assay showed high specificity, and was able to discriminate between complementary target miRNA-155 and single-base mismatch miRNA. In addition, this assay revealed good sensitivity and specificity with MCF-7 Breast cancer cells concentrations from 1000 to 45000 cells/mL with correlation coefficient of 0.9937 and detection limit of 600 cells/mL (6 cells in 10 μL of injected sample. Furthermore, with analysis of human serum samples which have been spiked with standard micro-RNA concentration the accuracy of the sensing assay-for the measuring of miRNA in human serum samples has been successfully demonstrated with satisfactory results.