Dual dye-labeled G-quadruplex aptasensor for detection of thallium(I) using ratiometric fluorescence resonance energy transfer

A fluorescent probe was developed for ratiometric detection of thallium ions in mineral water samples by modifying a G-rich aptamer (PS2.M 7) with a fluorescence donor (Cyanine-3, Cy-3) and a quencher (Cyanine-5, Cy-5). The probe had a random coil structure that changed into a G-quadruplex structure upon binding with Tl+. This change in structure decreased the distance between the donor and acceptor moieties, which resulted in fluorescence resonance energy transfer between Cy-3 and Cy-5. Under optimized conditions, the limit of detection and linear concentration range for Tl+ were 30.1 mu M (3 sigma) and 10 mu M-10 mM (R-2 = 0.9981), respectively. This simple and cost-effective fluorescence sensor provided satisfactory results for detection of thallium ions in spiked mineral water samples.

Automated summary

A fluorescent probe was developed for ratiometric detection of thallium ions in mineral water samples by modifying a G-rich aptamer. The probe changes its structure from a random coil to a G-quadruplex upon binding with Tl+, allowing for fluorescence resonance energy transfer between the donor and acceptor moieties. Under optimized conditions, the probe provided satisfactory results with a detection limit of 30.1 μM and a linear concentration range of 10 μM-10 mM.