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 Cu 2+ , the probe shows high sensitivity and selectivity for detecting Cu 2+ in other interferential metal ions coexisted system. Importantly, the fluorescence intensity of NALC-CdS QDs changes upon the concentration of Cu 2+ , the probe displays an excellent linear relationship between the fluorescence quenching rate and the concentration of Cu 2+ in ranging from 1 to 25 μM. Besides, the detected limitation of the probe towards Cu 2+ as low as 0.48 μM. The measurement of Cu 2+ 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 Cu 2+ detection in practical application.
The excessive use of nitro compounds and antibiotics has made them the main pollutants in the water environment. It is necessary and challenging to find an effective method to monitor them. Herein, a novel Cd(II) metal–organic complex (MOC) with one‐dimensional structure [Cd(L)2(H2O)2]·8H2O [HL = 2,4‐bis (triazol‐1‐yl) benzoic acid] has been synthesized and characterized. The complex can be used as a fluorescence sensor to detect nitroimidazole antibiotics and p‐nitrophenol in aqueous solutions. The limit of detection (LOD) of p‐nitrophenol and nitroimidazole antibiotics (metronidazole, ornidazole, dimethylimidazole) are 0.04, 0.02, 0.07, and 0.08 μM, respectively. The complex still maintains high reproducibility after five cycles. In summary, due to the strong stability, high sensitivity, and excellent selectivity of the synthesized complex, it provides a convenient method for the development of analytical platforms for detecting water pollutants.
Quantum dots nanomaterials have attracted extensive interest for fluorescence chemical sensors due their attributes, such as excellent optical characteristics, quantum size effects, interface effects, etc. Moreover, the fluorescence properties of quantum dots can be adjusted by changing their structure, size, morphology, composition, doping, and surface modification. In recent years, quantum dots nanomaterials have been considered the preferred sensing materials for the detection of heavy metal ions and pesticide residues by the interactions between quantum dots and various analytes, showing excellent sensitivity, selectivity, and interference, as well as reducing the cost of equipment compared with traditional measurement methods. In this review, the applications and sensing mechanisms of semiconductor quantum dots and carbon-based quantum dots are comprehensively discussed. The application of semiconductor quantum dots, carbon quantum dots, graphene quantum dots, and their nanocomposites that are utilized as fluorescence sensors are discussed in detailed, and the properties of various quantum dots for heavy metal ion and pesticide residue determination are also presented. The recent advances in and application perspectives regarding quantum dots and their composites are also summarized.
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