A sensitive fluorescence sensor based on a glutathione modified quantum dot for visual detection of copper ions in real samples.

Copper (Cu), as a heavy metal, accumulates in the human body to a certain extent, which can induce various diseases and endanger human health. Rapid and sensitive detection of Cu is highly desired. In present work, a glutathione modified quantum dot (GSH-CdTe QDs) was synthesized and applied in a "turn-off" fluorescence probe to detect Cu. The fluorescence of GSH-CdTe QDs could be rapidly quenched in the presence of Cu through aggregation-caused quenching (ACQ), resulting from the interaction between the surface functional groups of GSH-CdTe QDs and Cu and the electrostatic attraction. In the range of 20-1100 nM, the Cu concentration showed a good linear relationship with the fluorescence decline of the sensor, and the LOD is 10.12 nM, which was lower than the U.S. Environmental Protection Agency (EPA) defined limit (20 μM). Moreover, aiming to attain visual analysis, colorimetric method was also used for rapidly detecting Cu by capturing the change in fluorescence color. Interestingly, the proposed approach has successfully been applied for the detection of Cu in real samples (i.e., environment water, food and traditional Chinese medicine) with satisfactory results, which provides a promising strategy for the detection of Cu in practical application with the merits of being rapid, simple and sensitive.