| MicroRNAs (miRNAs) are a class of small, endogenous noncoding RNAs with a length of about 22 nt and proceeded from large hairpin precursors by Dicer enzyme.MiRNAs can inhibit the expression of target gene by forming RNA induced silencing complex (RISC). Numerous researches showed that miRNA plays important role in a various of biological processes, such as cell differentiation, apoptosis and immunological response, etc. An increading evidence shown that daberrant expression level of miRNA has a close relationship with the initiation of cancer as well as tumor stage. Recent researches indicated that miRNA can be used as biomarkers for diagnosis and prognosis and as target for the discovery of new drugs.Duplex-specific nuclease (DSN) is a kind of nuclease isolated from hepatopancreas of king crab Paralithodes Camtschaticus. DSN exhibits unique substrate specificity and hydrolyzes only dsDNA or DNA in DNA/RNA hybrids, regardless of nucleotide sequence, and does not cleave single-stranded (ss) DNA or RNA at all. In addition, DSN can discriminate single-base mismatch within a certain base length, which endows DSN a more charming property. Thus, DSN is a promising tool in fields of biomedical, biological science applications and bioanalysis.The unique properties of DSN can be used for signal amplification in miRNA detection, which can overcome many shortcomings brought by the characteristics of miRNA, such as sequence homology among family members, short length, and low abundance in total RNA samples. We designed gold nanoparticle aggregation colorimetric method and chemiluminiscence resonance energy transfer (CRET) method for miRNAs detection, incorporating the unique properties of DSN with the advantages of large extinction coefficient of gold nanoparticles and the CRET effect based on polydopamine nanoparticles (PDA), respectively. Our methods are simple, cost-effective, and can detect miRNA at the level of pM, which also can analyze miRNA in cell lysis directly. |
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