Highly selective and sensitive determination of copper ion based on a visual fluorescence method

A novel ratiometric fluorescence sensor for rapid and on-site visual detection of Cu2+ was designed and synthesized by integrating yellow-emission rhodamine fluorophore (RL) and red-emission CdTe@SiO2 QDs. The as-prepared nanohybrid fluorescence sensor shows dual-emissions at 537 nm and 654 nm under a single excitation at 500 nm in the presence of Cu2+. Owing to the strong chelating ability of RL toward Cu2+, the yellow fluorescence of RL could be selectively enhanced while the red fluorescence of CdTe QDs is almost unchanged, leading to an obvious fluorescence color change from red to yellow, which could be used for visual and ratiometric detection of Cu2+. This nanohybrid sensor exhibits excellent selectivity, sensitivity and anti-interference to Cu2+ detection and the detection limit is as low as 8.4 nM. Additionally, a simple device test strip for rapid and on-site detection of Cu2+ has been designed by immobilizing the RL-CdTe@SiO2 QDs on a common filter paper. This simple and effective paper-based sensor has a visual detection limit of 0.5 mu M, showing its promising application for on-site and rapid sensing of Cu2+ in pollution water. (C) 2016 Elsevier B.V. All rights reserved.