Ce(Ⅲ) Induced Type Copper Nano Clusters Strong Fluorescence System Construction And Application In Trace Pollutants Detection

Copper nanoclusters（CuNCs）are widely used due to their excellent water solubility,good biocompatibility,and low toxicity.The results found that CuNCs synthesized using sulfhydryl small molecules have unique aggregation-induced luminescence properties.At the same time,carbon quantum dots（CQDs）have highly abundant hydrophilic functional groups in their structure,such as carboxyl,amino and so on.CQDs with different sizes,structures and properties can be obtained by selecting carbon sources and modifiers,controlling the differences in synthesis conditions and process technology.In this paper,glutathione-capped copper nanoclusters（GSH-CuNCs）were synthesized by a simple one pot method and according to the aggregation-inducing effect,trivalent cerium ions(Ce³⁺)were used to enhance their fluorescence emission,and a strong fluorescence system was constructed to realize for p-nitrophenol（p-NP）.Then,nitrogen-doped carbon quantum dots（N-CQDs）were synthesized by hydrothermal method,and ratio-type fluorescent probes were constructed with GSH-CuNCs.Based on the sensitivity of the mixed fluorescent probe to the change of pH,a pH-responsive ratiometric fluorescence system was constructed to achieve specific detection of organophosphorus pesticides（OPs）.The following is the specific content:（1）Application of CuNCs-based Strong fluorescence system in the detection of p-NPFirstly,GSH-CuNCs were synthesized by a simple one-pot method.Secondly,morphology and structure of GSH-CuNCs were characterized by TEM,XPS,Fourier infrared spectroscopy,etc,indicating the successful synthesis of the material.Finally,it was found that trivalent cerium(Ce³⁺)could induce the aggregation of GSH-CuNCs and which increased the fluorescence intensity by 41.7 times.As a result,a strong fluorescence system was established.After a series of optimization of conditions,the trace detection of p-NP was realized,and good linearity was obtained from 0.5 to 500μM（R²=0.9961）,and the detection limit was as low as 0.17μM.Finally,in order to verify the feasibility of the fluorescence platform based on GSH-CuNCs-Ce³⁺,we studied the recovery rate of p-NP in tap water,river water and landfill leachate.At the three spiked levels（10,50 and 200μM）,the spiked recovery rate of p-NP ranges from95.6%to 106.0%,and the relative standard deviation（RSD）is less than<1.8%.The results show that the fluorescence analysis method based on the rapid response and strong anti-interference ability of the GSH-CuNCs-Ce³⁺hybrid system.It has excellent sensitivity for p-NP detection and shows great potential in routine monitoring of p-NP in conventional water bodies.（2）Application of a pH sensor-oriented ratiometric fluorescence system constructed by CuNCs and N-CQDs in the detection of OPsFirst,N-CQDs were synthesized by a simple hydrothermal method,and their fluorescence properties were tested with a fluorescence spectrometer.Owing to the excitation wavelengths of N-CQDs and GSH-CuNCs are the same,and two different emission peaks can be obtained at the same excitation wavelength,so a ratio fluorescence system is constructed.After verification,the constructed ratio fluorescence system has a linear fluorescence intensity change between pH 3-5.It is known that the presence of OPs residues can significantly reduce the acetylcholinesterase（ACh E）activity in plant or animal tissues.Because ACh E can catalyze acetylcholine（ATCh）to produce thiocholine and acetic acid,the formation of acetic acid will change the pH value of the solution,causing the fluorescence intensity of the fluorescent probe to increase or quench.Thereby establishing pH-directed fluorescence the system was used for quantitative detection of OPs,and good linearity was obtained from 0.25 to 200μM（R²=0.9965）,and the detection limit was as low as 0.08μM.In order to verify the feasibility of detection based on this method,the actual samples were measured in six kinds of boxed juice drinks.At the three spiked concentration levels（5,10,and 50μM）,the enhanced recovery rate of malathion ranges from 96%to 106.0%,and the relative standard deviation（RSD）is less than<1.3%.The results show that this fluorescence system has excellent sensitivity for the detection of malathion,and can be used to detect OPs in common fruit juice drinks which has application potential.In summary,we have prepared CuNCs and N-CQDs with aggregation-induced luminescence properties,and successfully used them for the detection of p-NP and OPs.First of all,the fluorescence intensity of cuncs was enhanced dozens of times by using the aggregation induced property of cuncs,and the determination of p-NP was realized.Secondly,using N-CQDs,a ratio-based fluorescence system that can change the fluorescence intensity due to the influence of pH in the solution was constructed,and based on this,a method for detecting OPs was provided.The research not only established a detection strategy based on aggregation-induced luminescence mechanism and broadened the comprehensive application of CuNCs and CQDs,but also provided a reliable and sensitive method for detecting p-NP and OPs.