The Study On The New Analytical Methods For Sensitive Mirna Detection Based On Enzyme-catalyzed Signal Amplification Strategy

MiRNA is endogenous small non-coding RNA molecules (19-25nucleotides), which regulate gene expression post-transcriptionally. Researches have demonstrated that the expression of miRNA is strongly associated with the tumorgenesis and clinical treatment response, which make miRNA become an ideal class of biomarker. Thus, developing simple, sensitive and selective miRNA detection is of great importance in understanding biological functions of miRNA as well as in early diagnosis of cancers.We have developed two methods to quantatively detect miRNA based on isothermal exponential amplification reaction. G-rich DNA sequences can interact with hemin to fold into G-quadruplex. G-quadruplex DNAzyme, reveals a horseradish peroxidase (HRP) mimicking activity, and can catalyze the H2O2-mediated oxidation of2,2-azinobis (3-ethylbenzothiozoline)-6-sulfonic acid (ABTS2-) and with a color change. To use the property, we have developed a sensitive method for miRNA detection based on isothermal exponential amplification-assisted generation of catalytic G-quadruplex DNAzyme. The proposed assay can selectively detect miRNA with a low detection limtit of1fM.CuNC is the core/shell type molecular aggregate structure. The core is consisted of several to dozens of copper atoms and the shell is comprised of hydrophilic and biocompatible DNA. CuNCs have become a noval fluorescent quantum dots materials which can be applied to bioanalysis and clinical diagnosis due to the characteristics of high quantum yield、adjustable fluorescence emission wavelength and resistance to photobleaching and so on. Thus, we have designed a facile and label-free method for sequence-specific miRNAs detection using fluorescent dsDNA-templated copper nanoclusters as signal output. The proposed assay showed a low detection limit of1pM and with excellent selectivity.