A ratiometric fluorescent nanoprobe based on CdSe quantum dots for the detection of Ag+ in environmental samples and living cells

With the widespread application of Ag + in modern life and industry, the potential hazardous effects of Ag + to environment and humans have attracted great concerns. Thus, effective and rapid strategies for Ag + detection are highly desirable. In this paper, a novel ratiometric fluorescence sensor using CdSe quantum dots (QDs) has been constructed for sensitive and selective detection of Ag + , which is based on the formation of Ag 2 Se QDs. CdSe QDs were initially prepared and showed single wavelength emission at 510 nm. When Ag + exists, a rising peak appeared at 650 nm and the emission at 510 nm declined, exhibiting distinct ratiometric fluorescence emission ( I 650 / I 510 ) characteristic with a linear response over the Ag + concentration range of 0.01–4 μM. Significantly, the fluorescence changed from green to red. The detection limit of the constructed sensor is 1.4 nM. Furthermore, the sensing assay can be successfully applied to detect Ag + in real water samples and living cells.