Synthesis of CuInS2 Quantum Dots Modified with Alanine for Sensitive and Selective Detection of Pb2+ and Cysteine

In this study, a novel fluorescent probe based on CuInS 2 quantum dots modified with alanine (Ala-CuInS 2 QDs) was developed for the detection of lead ions and cysteine (Pb 2+ and Cys). Ala-CuInS 2 QDs were synthesized through a one-step hydrothermal method exhibiting uniform size, good stability and water solubility. The QDs were then utilized as an “on-off-on” fluorescence sensor to detect Pb 2+ and Cys in the ranges of 0–20 µM and 0–55 µM respectively, with detection limits of 0.29 µM and 0.66 µM. The mechanism of fluorescence quenching and recovery processes was also explored. Furthermore, Ala-CuInS 2 QDs have been successfully applied to detect Pb 2+ in tap and river water and detect cysteine in serum.