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

Abstract

In this study, a novel fluorescent probe based on CuInS₂ quantum dots modified with alanine (Ala-CuInS₂ QDs) was developed for the detection of lead ions and cysteine (Pb²⁺ and Cys). Ala-CuInS₂ 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 Pb²⁺ 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-CuInS₂ QDs have been successfully applied to detect Pb²⁺ in tap and river water and detect cysteine in serum.

Keywords: CuInS2 quantum dots; Cysteine; Fluorescent probe; Lead ions.