title: Silver ions-mediated conformational switch: facile design of structure-controllable nucleic acid probes.
abstract: Conformationally constraint nucleic acid probes were usually designed by forming an intramolecular duplex based on Watson-Crick hydrogen bonds. The disadvantages of these approaches are the inflexibility and instability in complex environment of the Watson-Crick-based duplex. We report that this hydrogen bonding pattern can be replaced by metal-ligation between specific metal ions and the natural bases. To demonstrate the feasibility of this principle, two linear oligonucleotides and silver ions were examined as models for DNA hybridization assay and adenosine triphosphate detection. The both nucleic acids contain target binding sequences in the middle and cytosine (C)-rich sequences at the lateral portions. The strong interaction between Ag(+) ions and cytosines forms stable C-Ag(+)-C structures, which promises the oligonucleotides to form conformationally constraint formations. In the presence of its target, interaction between the loop sequences and the target unfolds the C-Ag(+)-C structures, and the corresponding probes unfolding can be detected by a change in their fluorescence emission. We discuss the thermodynamic and kinetic opportunities that are provided by using Ag(+) ion complexes instead of traditional Watson-Crick-based duplex. In particular, the intrinsic feature of the metal-ligation motif facilitates the design of functional nucleic acids probes by independently varying the concentration of Ag(+) ions in the medium.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China.
authors.forename: Yongxiang
authors.initials: Y
authors.lastname: Wang
authors.forename: Jishan
authors.initials: J
authors.lastname: Li
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Jianyu
authors.initials: J
authors.lastname: Jin
authors.forename: Jinhua
authors.initials: J
authors.lastname: Liu
authors.forename: Kemin
authors.initials: K
authors.lastname: Wang
authors.forename: Weihong
authors.initials: W
authors.lastname: Tan
authors.forename: Ronghua
authors.initials: R
authors.lastname: Yang
mesh_terms: D006860:Hydrogen Bonding; D007477:Ions; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D007477:Ions; D015345:Oligonucleotide Probes; D009841:Oligonucleotides; D012834:Silver