title: Intra-molecular G-quadruplex structure generated by DNA-templated click chemistry: "turn-on" fluorescent probe for copper ions.
abstract: A novel homogenous fluorescent sensor for signal-on detection of Cu(2+) has been developed based on intra-molecular G-quadruplex formed by DNA-templated click reaction and crystal violet (CV) as label-free signal reporter. The clickable DNA probe consists of two G-rich strands (A and B) bearing azide and alkyne group, respectively, and a template strand (C) locating two proximate reactants by pairing with A and B. The sequences of A and B are derived from asymmetric split of the G-quadruplex sequence (TTAGGG)4. In the presence of Cu(2+), the whole G-quadruplex sequence A-B is generated by chemical ligation of A and B via copper ion-catalyzed alkyne-azide cycloaddition, then released from template by toehold strand displacement, and consequently forming a stable intra-molecular G-quadruplex, which binds with CV to generate a strong fluorescent signal. Oppositely, weak fluorescence was obtained without Cu(2+) because of unstable intermolecular G-quadruplex formed by A and B and lack of lateral loop connection. Therefore, the Cu(2+) can be sensitively and specifically detected by the fluorescence of the CV-stained G-quadruplex with a low detection limit of 65nM and a linear range of 0.1-3µM. This method rationally integrated the DNA-templated synthesis and G-quadruplex structure-switch, presenting a simple and promising approach for biosensor development.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China; Yunnan Academy of Tobacco Science, Kunming 650106, PR China.
authors.forename: Qinpeng
authors.initials: Q
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Lifen
authors.initials: L
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Yijia
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China. Electronic address: yanhuang.hnu@gmail.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Binbin
authors.initials: B
authors.lastname: Xiang
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China. Electronic address: niezhou.hnu@gmail.com.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Nie
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Shouzhuo
authors.initials: S
authors.lastname: Yao
mesh_terms: D057930:Click Chemistry / Q000379:methods*; D003300:Copper / Q000032:analysis* / Q000737:chemistry; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure; D005456:Fluorescent Dyes / Q000032:analysis / Q000138:chemical synthesis*; D054856:G-Quadruplexes; D007477:Ions; D054802:Molecular Imprinting / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D007477:Ions; D003300:Copper; D004247:DNA
keywords: Click chemistry; Copper ion; Crystal violet (CV); DNA-templated organic synthesis (DTS); G-quadruplex