Synthesis Of Porphyrin-based Metal Organic Framework Materials And Application In Food Detection

With the increasing improvement of people’s living standards,food safety is becoming increasingly important,and quantitative research with excellent performance is also particularly important for food and safety control.Fluorescent sensing technology has received widespread attention and application in recent years due to its advantages of simple operation,high sensitivity,and rapid response.Porphyrin is a multi dentate organic ligand that can provide two coordination atoms.It has a planar macrocyclic structure and strong fluorescence in solution.The metal organic framework material composed of porphyrin as an organic ligand not only has good fluorescence performance of porphyrin itself,but also has the advantages of porous materials.Its special pore structure can achieve pre concentration of the target analyte.This article focuses on food detection as an application direction,using porphyrins as organic ligands and metal zirconium clusters as inorganic nodes,to prepare metal organic framework materials PCN-224 and PCN-224（Zn）,which exhibit the fluorescence characteristics of porphyrins.PCN-224 itself has exposed carboxylic acid recognition sites,which can provide more ideas for sensor design.The material properties of PCN-224 and its derivatives were studied using characterization and analysis techniques.Based on the prepared PCN-224 and PCN-224（Zn）nanomaterials,a highly selective and sensitive fluorescent nanosensor was constructed for the detection of target analytes in food samples or other complex environments.The main research content of this article is as follows:Chapter 1:Introduction to metal organic framework materials and their synthesis,composite material design strategies,and their applications in the field of sensors.Chapter 2:A simple and effective high-sensitivity sensor PCN-224/H₂PO₄^-detects sulfite(SO₃^2-)in food.Fluorescent porphyrin-based MOFs（PCN-224）were synthesized,its synthesis conditions were optimized,and it was characterized by various means,and further it was used as an enhanced fluorescence sensor for SO₃^2-detection.The fluorescence peak of PCN-224 is located at 664 nm.In the presence of SO₃^2-,the acid-base reaction between H₂PO₄^-and SO₃^2-promoted the production of PO₄^3-,which formed a Zr-OP bond with PCN-224 and enhanced the fluorescence intensity of PCN-224 at 664 nm.Therefore,the sensing system PCN-224/H₂PO₄^-was constructed using H₂PO₄^-as an auxiliary agent.The fluorescence enhancement of PCN-224/H₂PO₄^-showed a good linear relationship in the range of 0.01-18μM,and the detection limit was as low as 3.8 n M.In addition,the constructed PCN-224/H₂PO₄^-sensor system can be successfully used for the detection of SO₃^2-in granulated sugar with recoveries ranging from 100.17%to 106.25%,proving that the PCN-224/H₂PO₄^-nanosensor can detect SO₃^2-in real samples Feasibility.Chapter 3:Based on the PCN-224 synthesized in the second chapter,PCN-224（Zn）was synthesized by doping Zn²⁺into PCN-224,its synthesis conditions were optimized,and it was characterized by various means.It acts as a fluorescence-enhanced sensor of GSH and optimizes its detection conditions.By reacting GSH with Zn²⁺in PCN-224（Zn）to generate Zn S precipitate,a small part of Zn²⁺was taken away from PCN-224 to restore the fluorescence at 610 nm to achieve the effect of detecting GSH.The sensor exhibited good linearity in the range of 0.01～6μM,and the detection limit was as low as 1.5 n M.The sensor can be successfully used for the detection of GSH in actual samples,and the recovery rate is between 99.58%and 100.45%,which proves the feasibility of PCN-224（Zn）sensor for detecting GSH in actual samples.Chapter 4:Summarize the advantages of the two fluorescent nanosensing systems constructed in this paper in food sample analysis and prospect their limitations and application prospects based on existing work progress.