Excellent fluorescence detection of Cu ²⁺ in water system using N-acetyl-L-cysteines modified CdS quantum dots as fluorescence probe

Abstract

View of the negative influence of metal ions on natural environment and human health, fast and quantitative detection of metals ions in water systems is significant. Ultra-small grain size CdS quantum dots (QDs) modified with N-acetyl-L-cysteines (NALC) (NALC-CdS QDs) are successfully prepared via a facile hydrothermal route. Based on the changes of fluorescence intensity of NALC-CdS QDs solution after adding metal ions, the fluorescence probe made from the NALC-CdS QDs is developed to detect metal ions in water systems. Among various metal ions, the fluorescence of NALC-CdS QDs effectively quenched by the addition of Cu²⁺, the probe shows high sensitivity and selectivity for detecting Cu²⁺in other interferential metal ions coexisted system. Importantly, the fluorescence intensity of NALC-CdS QDs changes upon the concentration of Cu²⁺, the probe displays an excellent linear relationship between the fluorescence quenching rate and the concentration of Cu²⁺in ranging from 1 to 25<i>μ</i>M. Besides, the detected limitation of the probe towards Cu²⁺as low as 0.48<i>μ</i>M. The measurement of Cu²⁺in real water sample is also carried out using the probe. The results indicate that NALC-CdS QDs fluorescence probe may be a promising candidate for quantitative Cu²⁺detection in practical application.