title: In situ DNA-templated synthesis of silver nanoclusters for ultrasensitive and label-free electrochemical detection of microRNA.
abstract: On the basis of the use of silver nanoclusters (AgNCs) in situ synthesized by cytosine (C)-rich loop DNA templates as signal amplification labels, the development of a label-free and highly sensitive method for electrochemical detection of microRNA (miRNA-199a) is described. The target miRNA-199a hybridizes with the partial dsDNA probes to initiate the target-assisted polymerization nicking reaction (TAPNR) amplification to produce massive intermediate sequences, which can be captured on the sensing electrode by the self-assembled DNA secondary probes. These surface-captured intermediate sequences further trigger the hybridization chain reaction (HCR) amplification to form dsDNA polymers with numerous C-rich loop DNA templates on the electrode surface. DNA-templated synthesis of AgNCs can be realized by subsequent incubation of the dsDNA polymer-modified electrode with AgNO3 and sodium borohydride. With this integrated TAPNR and HCR dual amplification strategy, the amount of in situ synthesized AgNCs is dramatically enhanced, leading to substantially amplified current response for highly sensitive detection of miRNA-199a down to 0.64 fM. In addition, the developed method also shows high selectivity toward the target miRNA-199a. Featured with high sensitivity and label-free capability, the proposed sensing scheme can thus offer new opportunities for achieving sensitive, selective, and simple detection of different types of microRNA targets.
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, P.R. China.
authors.forename: Cuiyun
authors.initials: C
authors.lastname: Yang
authors.forename: Kai
authors.initials: K
authors.lastname: Shi
authors.forename: Baoting
authors.initials: B
authors.lastname: Dou
authors.forename: Yun
authors.initials: Y
authors.lastname: Xiang
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
mesh_terms: D015342:DNA Probes / Q000737:chemistry* / Q000235:genetics*; D055664:Electrochemical Techniques / Q000379:methods*; D006801:Humans; D035683:MicroRNAs / Q000097:blood / Q000737:chemistry / Q000235:genetics*; D012680:Sensitivity and Specificity; D012834:Silver / Q000737:chemistry; D013698:Templates, Genetic
chemical_list: D015342:DNA Probes; D035683:MicroRNAs; C531408:mirn199 microRNA, human; D012834:Silver
keywords: MicroRNA; electrochemical; label-free; serum; signal amplification; silver nanoclusters