Abstract
We report a ratiometric fluorescence nanosensor for selective and visual detection of Cd2+ using quencher displacement-induced fluorescence recovery of CdTe quantum dots (QDs)-based hybrid probe. In this design, the red emissive CdTe QDs (rQDs) embedded in silica sphere have been played the role of internal reference signal, while the green emissive CdTe QDs (gQDs) covalently bound on silica surface served as the specific recognition element. The complexation of 1,10-phenanthroline (Phen) with the ratiometric fluorescence probe resulted in the fluorescence quenching of gQDs while the fluorescence of the rQDs inner silica stayed constant. Upon exposure to different amounts of Cd2+, the fluorescence of gQDs could be selectively recovered to a certain extent due to the detachment of Phen ligands from gQDs surface. Based on the “off-on” green fluorescence of gQDs and the red background emitted by rQDs, a ratiometric fluorescence nanosensor for Cd2+ detection was successfully achieved in a wide concentration range of 0.5nM–2μM. More importantly, one can recognize for Cd2+ content by the naked eye with high resolution in a range of 2 nM–1μM. This nanosensor features to distinctly discriminate between Cd2+ and Zn2+, and succeeded in real tap water and rice samples.
Published Version
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