A Label-Free Oligonucleotide Based Thioflavin-T Fluorescent Switch for Ag+ Detection with low Background Emission

Abstract

A novel fluorescent Ag(+) sensor was developed based on the label-free silver (I) specific oligonucleotide (SSO) and Thioflavine T (ThT) monomer-excimer switch. C-rich SSO which contain C-C mismatched base pairs can selectively bind to Ag(+) ions and the formed duplexes which constructed by C-Ag(+)-C structure are thermally stabilized without largely altering the double helical structure. ThT give very weak fluorescent in bulk solution and/or in the presence of SSO. However ThT shows high fluorescence in the presence of SSO and Ag(+) at the same time mainly because ThT excimer, which has the high quantum yield, formed and stabilized in the minor or major groove. Based on the discovery, we developed the novel Ag(+) sensor. Under the optimum condition, the selectivity of this system for Ag(+) over other metal ions in aqueous solution is remarkably high, and Ag(+) can be quantified over the dynamic range of 30-450 nM, with a limit of detection of ~16 nM and a linear correlation coefficient of 0.995.

Metal ion coordination delays amyloid-β peptide self-assembly by forming an aggregation–inert complex

“…S1 and S2). With pFTAA we observed the typical sigmoidal aggregation kinetic traces (50,51), while the monitoring of aggregation by ThT is interfered by interactions of Ag(I) and ThT (52,53) (Fig. S1), which makes ThT unsuitable for aggregation kinetics in the presence of Ag(I) (Supporting information text, page S4).…”

Selective recognition of ds-DNA cavities by a molecular rotor: switched fluorescence of thioflavin T

“…6 In the course of elucidating the fluorescence mechanisms to develop sensing of fibril formation and native protein binding, less attention has been paid to another biopolymer: nucleic acid. [26][27][28][29] Because of the coexistence of nucleic acids and functional proteins in a cell, it is very important to have an insight into the emission resulting from ThT binding to DNA and RNA. This would be very helpful in determining the factors that contribute to the ThT emission for use of the dye as an in vivo diagnostical tool and even its biological functions such as extending the induced lifespan.…”

A label-free fluorescent molecular switch for a DNA hybridization assay utilizing a G-quadruplex-selective auramine O

“…26-fold, curve b) in the presence of dsDNA, which might be caused by the excimer formation similar to the observations made by our lab and others for the dye Thioflavin T (ThT) and dsDNA. [30][31][32] The fluorescence of AO increased to a most remarkable extent (ca. 240-fold, curve a) in the presence of the G-quadruplex, showing a strong interaction with the aid of K + .…”