Research On Detection Of Copper Ions And Fish Freshness Based On Quantum Dots

In recent years,due to the advantages of quantum dots with wide excitation,narrow emission,tunable size,controllable luminescence and continuous absorption curve,quantum dots as a new type of fluorescent nanosensor show rapid identification and high sensitivity compared with traditional detection methods.It has the advantages of simple operation and good selectivity,and has a wide range of application prospects in the field of detection.Aiming at the problems of heavy metal Cu²⁺and fish freshness detection in the field of food safety,MPA-InP/ZnS quantum dots with low toxicity,high sensitivity and high selectivity were synthesized and improved,and used as fluorescent probes for spectral analysis and mechanism.The main research work is as follows:（1）This paper briefly introduces the research status of Cu²⁺detection and fish freshness detection,introduces the importance and practical application value of Cu²⁺detection and fish freshness detection,and summarizes the current difficulties and challenges encountered in Cu²⁺detection and fish freshness detection.The development history and research status of quantum dots are reviewed,the types and functionalization methods of quantum dots are introduced,and the current fluorescence response mechanism of quantum dots is summarized.Combining the above-mentioned characteristics of Cu²⁺detection and fish freshness detection,a new functional quantum dot was designed,and a fluorescence method based on the new functional quantum dot was proposed.（2）A highly sensitive and selective fluorescent probe based on thiopropionic acid（MPA）-terminated InP/ZnS quantum dots（MPA-InP/ZnS QDs）was designed to detect trace amounts of Cu in water,and based on this Probe-synthesized PVA/MPA-InP/ZnS QDs thin films.In the presence of Cu²⁺,the carboxyl groups on the surface of MPA-InP/ZnS QDs combine with Cu²⁺,that is,a static quenching effect occurs,and the fluorescence of MPA-InP/ZnS QDs and PVA/MPA-InP/ZnS QDs films is significantly reduced.quenched.Finally,further application of MPA-InP/ZnS quantum dot probes and PVA/MPA-InP/ZnS QDs films to the detection of trace Cu²⁺in real water and beverage samples has good feasibility.（3）A visualized fluorescent probe based on MPA-InP/ZnS quantum dots and sodium roseate（SR）was designed for real-time non-destructive monitoring of fish freshness.In the MPA-InP/ZnS QDs-SR system,the fluorescence of MPA-InP/ZnS QDs is quenched by SR due to the combined effect of internal filtering effect（IEF）and static quenching effect（SQE）.When ammonia was added,the IEF and SQE were weakened,and the fluorescence of the fluorescent probe recovered,and the color of the fluorescent probe solution changed from colorless to bright orange-red under ultraviolet light（365 nm）.The visualized fluorescent probe has a good linear relationship between the fluorescence intensity and total color change（ΔE）at room temperature（25°C）and refrigerated temperature（4°C）and the volatile base nitrogen（TVB-N）of fish meat.It has potential application value in monitoring fish freshness.