Substrate specificity-enabled terminal protection for direct quantification of circulating MicroRNA in patient serums
Li, JY (Li, Junyao)[ 1 ] ; Fu, WX (Fu, Wenxin)[ 1 ] ; Wang, ZY (Wang, Zhaoyin)[ 1 ]*（王兆寅）; Dai, ZH (Dai, Zhihui)[ 1,2 ]*（戴志晖）
[ 1 ] Nanjing Normal Univ, Jiangsu Collaborat Innovat Ctr Biomed Funct Mat, Jiangsu Key Lab Biofunct Mat, Schaal Chem & Mat Sci, Nanjing 210023, Jiangsu, Peoples R China
[ 2 ] Nanjing Normal Univ, Ctr Anal & Testing, Nanjing 210023, Jiangsu, Peoples R China
Currently, reported affinity pairings still lack in diversity, and thus terminal protection relying on steric hindrance is restricted in designing nucleic acid-based analytical systems. In this work, resistance to exonuclease is testified by group modification or backbone replacement, and the 3 '-phosphate group (P) reveals the strongest exonuclease I-resistant capability. Due to the substrate specificity of enzymatic catalysis, this 3 '-P protection works in a direct mode. By introducing DNA templated copper nanoparticles, an alkaline phosphatase assay is performed to confirm the 3 '-P protection. To display the application of this novel terminal protection, a multifunctional DNA is designed to quantify the model circulating microRNA (hsa-miR-21-5p) in serums from different cancer patients. According to our data, hsa-miR-21-5p-correlated cancers can be evidently distinguished from non-correlated cancers. Meanwhile, the effect of chemotherapy and radiotherapy on breast cancer is evaluated from the perspective of hsa-miR-21-5p residue in serums. Since greatly reducing the limitations of DNA design, this P-induced terminal protection can be facilely integrated with other DNA manipulations, thereby constructing more advanced biosensors with improved analytical performances for clinical applications.