title: Label-Free Ag⁺ Detection by Enhancing DNA Sensitized Tb(3+) Luminescence.
abstract: In this work, the effect of Ag⁺ on DNA sensitized Tb(3+) luminescence was studied initially using the Ag⁺-specific RNA-cleaving DNAzyme, Ag10c. While we expected to observe luminescence quenching by Ag⁺, a significant enhancement was produced. Based on this observation, simple DNA oligonucleotide homopolymers were used with systematically varied sequence and length. We discovered that both poly-G and poly-T DNA have a significant emission enhancement by Ag⁺, while the absolute intensity is stronger with the poly-G DNA, indicating that a G-quadruplex DNA is not required for this enhancement. Using the optimized length of the G7 DNA (an oligo constituted with seven guanines), Ag⁺ was measured with a detection limit of 57.6 nM. The signaling kinetics, G7 DNA conformation, and the binding affinity of Tb(3+) to the DNA in the presence or absence of Ag⁺ are also studied to reveal the mechanism of emission enhancement. This observation is useful not only for label-free detection of Ag⁺, but also interesting for the rational design of new biosensors using Tb(3+) luminescence.
authors: Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada. kkleinke@uwaterloo.ca.
authors: Kimberly
authors: K
authors: Kleinke
authors: Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada. r.saran.bhatnagar@gmail.com.
authors: Runjhun
authors: R
authors: Saran
authors: Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada. liujw@uwaterloo.ca.
authors: Juewen
authors: J
authors: Liu
mesh_terms: D004247:DNA / Q000737:chemistry*; D021881:DNA, Catalytic / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D049449:Luminescence; D009690:Nucleic Acid Conformation; D012834:Silver / Q000032:analysis*; D013194:Staining and Labeling; D013725:Terbium / Q000737:chemistry*
chemical_list: D021881:DNA, Catalytic; D013725:Terbium; D012834:Silver; D004247:DNA
keywords: aptamers; biosensors; fluorescence; luminescence; silver; terbium