| Hypochlorous acid is an extremely important member of reactive oxygen species.It not only exists widely in nature as bleaching agent and disinfectant,but also participates in the regulation process of human life.However,the excessive utilization of hypochlorous acid will result in serious environmental pollution and have adverse effects on human health.Thus,developing a type of accurate,specific and rapid testing method for monitoring the concentration of hypochlorous acid in the water environment is of significant importance.Fluorescence detection technology can realize qualitative,quantitative and visual detection of various pollutants,which has attracted massive attention of researchers because of high sensitivity,excellent specificity,good repeatability and short response time.Fluorescent copper nanoclusters,which is a kind of easily synthesized,compatible with biological cells,ultrafine and stable fluorescent probe material,has the practical application potential to measure the level of substances existing in environmental and biological.In this work,a novel method for real-time,sensitive and selective detection of the hypochlorous acid concentration in the environment is designed,which is based on the fluorescence analysis technique as well as combined with the merits of fluorescent copper nanoclusters material.Firstly,a sort of copper nanoclusters probe with ascorbic acid as reducing agent and polyvinyl pyrrolidone as framework is synthesized in aqueous solution by adding a small amount of copper ions,and then the bright blue fluorescence can be observed.This kind of material exhibits the strengths such as good dispersibility in water with no precipitation for a long time,good quantum yield,salt tolerance,strong light stability and solid-state luminescence,which expand and facilitate its biological and environmental application.The copper nanoclusters showed a specific sensitive and rapid fluorescence quenching toward hypochlorous acid compared with other reactive oxygen species and ions that are found widely in the environment,and the limit of detection is calculated as 55 nM.The mechanism has been investigated and was attributed to the oxidation of reduced Cu on the surface of copper nanoclusters by hypochlorous acid.Surprisingly,when excessive iodide ions were present in the reaction system between the probe and hypochlorous acid,the fluorescence quenching degree of the probe was more obvious after adding hypochlorous acid,and the detection limit in this system is as low as 19 nM.We hypothesized and proved that the phenomenon is due to the product of reaction between hypochlorous acid and iodide could react with the reduced copper on the surface of the copper nanoclusters to produce surface defects,and there would be an internal optical filtering effect between the product and the probe.The combination of the above two factors leads to the improvement of the sensitivity of copper nanocluster-iodide-hypochlorous acid detection system,so iodide ions can be considered as the "sensitizer"of the system.In addition,owing to the certain action mechanism in the response process of the system,the addition order of excessive iodide and hypochlorous acid can impact the linear detection range and detection limit of the probe.Finally,the real-time,quantitative,highly sensitive and selective detection of hypochlorous acid in real water environment,which based on the excellent physical and chemical properties of the copper nanoclusters probe,is further realized. |
