title: Target-catalyzed hairpin assembly and intramolecular/intermolecular co-reaction for signal amplified electrochemiluminescent detection of microRNA.
abstract: Herein, a new electrochemiluminescence (ECL) strategy for enzyme-free microRNA-21 (miR-21) amplified detection was designed based on target-catalyzed hairpin assembly by combining the signal-amplification capability of both intramolecular and intermolecular ECL co-reaction. In this strategy, two hairpin DNA probes of H1 and H2 were designed as capture probes and detection probes, respectively. To be specific, the capture probes of H1 were immobilized on the multilayer interface of AuNPs and thiosemicarbazide (TSC) assembly on the single-walled carbon nanohorns decorated electrode, while the detection probes of H2 was anchored on the nanocarriers of gold nanoparticals functionalized reduced graphene oxide (Au-rGO) which were tagged with the self-enhanced ruthenium complex (PEI-Ru(ΙΙ)) in advance. Based on the target-catalyzed hairpin assembly, target miR-21 could trigger the hybridization of H1 and H2 to further be released for initiating the next hybridization process to capture a large number of H2 bioconjugates on the sensing surface. Herein, the TSC was used not only as a coupling reagent to attach the AuNPs via Au-S and Au-N bonds but also as a novel intermolecular coreactant to enhance the ECL intensity, and the PEI-Ru(ΙΙ) as emitters exhibited enhanced ECL efficiency. Therefore, a strong ECL signal was achieved by the dual amplification strategies of target recycle and the intramolecular/intermolecular co-reaction of PEI-Ru(ΙΙ) and TSC. The designed protocol provided an ultrasensitive ECL detection of miR-21 down to the sub-femtomolar level with a linear response about 6 orders of magnitude (from 1.0 × 10(-16)M to 1.0 × 10(-11)M) with a relatively low detection limit of 0.03 fM (S/N=3).
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Yu
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Ji-Peng
authors.initials: JP
authors.lastname: Wang
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Lin-Ru
authors.initials: LR
authors.lastname: Hong
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Ya-Qin
authors.initials: YQ
authors.lastname: Chai
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China. Electronic address: yuanruo@swu.edu.cn.
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China. Electronic address: yingzhuo@swu.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhuo
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D055029:Inverted Repeat Sequences / Q000235:genetics*; D008163:Luminescent Measurements / Q000295:instrumentation*; D035683:MicroRNAs / Q000032:analysis* / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D012663:Semicarbazides / Q000737:chemistry*
chemical_list: C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D012663:Semicarbazides; C005151:thiosemicarbazide
keywords: Electrochemiluminescence; Intermolecular co-reaction; Intramolecular co-reaction; Target recycle; microRNA-21