Preparation of CdTe quantum dots for detecting Cu(II) ions

Although copper is needed by the human body, excessive copper can cause diarrhea, vomiting, and neurological disorders. In this study, CdTe semiconductor quantum dots (QDs) with different emission wavelengths were fabricated and used for detection of copper ions. By controlling the temperature, nucleation and growth of the crystals in the aqueous phase were separated, which improved the optical properties of QDs. They were characterized with Fourier-transform infrared (FT-IR), Transmission electron microscope (TEM) and X-ray diffraction (XRD). After being coated by the sol-gel method, the QDs were used to detect Cu(II) ions. There was a good linear relationship between the concentration of Cu(II) ions and the quenching efficiency of fluorescent probes over the range 0–1 mg L−1, and the detection limit was 1.18 μg L−1 (n = 10). Ratiometric fluorescent probes were also fabricated, which exhibited better Cu(II) ion detection, with a detection limit as 0.13 μg L−1 (0.002 μmol/L) that was far lower than the detection standard of copper ions in water.