Application Of Fluorescent Polymer Nanoparticles In The Detection Of Sulfite?Copper Ions And Glutathione

This study is subordinate to the National Natural Science Foundation of China-the project of the Youth Science Foundation-?The Preparation of Semiconductor Quantum Dots and Their Application in the Field of Food Analysis??31772058?.With the rapid expansion of food-stuff industry,more and more new technologies are applied to food processing.The degree of industrialization of food processing has gradually deepened.However,The deepening of the degree of food processing industrialization has also brought some problems that can not be ignored,such as food additives have been used in large amounts in many parts of the world.In most countries there are laws safeguarding the health of public by limiting the use of additives,but there are still some producers using additives illegally.In addition,there are some producers claimed that there are some nutrients in their products but doesn't exist actually.In order to cooperate with the laws to better combat these illegal producers,researchers have developed more and more methods to detect toxic or harmful substances and nutrients in foods.Fluorescent polymer are also called conjugated polymers?CPs?,because of its unique fluorescence properties,fluorescent polymer are favored by many researchers in recent years.Researchers have developed numerous detection methods and analysis methods base on the function of fluorescent signal amplification-one of the most important properties of fluorescent polymer.The sensitivity of these methods is much higher than methods that developed by the fluorescent molecule.The conjugated polymers nanoparticles?CPNs?sensor that made of conjugated polymers are still inherit all kinds of excellent properties of conjugated polymers,such as high fluorescence intensity,large cross section,and strong resistance to photobleaching.In this study,we first optimized the preparation method of CPNs,and then made the polymer,Poly[{9,9-dihexyl-2,7-bis?1-cyanovinylene?fluorenylene}-alt-co-{2,5-bis?N,N?-diphenylamino?-1,4-phenylene}]?PFBD?,into two kinds of CPNs under optimized method?hanging drop method?,namely PFBD CPNs and NPG@PFBD CPNs.We established a kind of detection method for SO₃^2-based on PFBD CPNs.At first,we add 1,4-benzoquinone to the PFBD CPNs colloid system?water system?.1,4-benzoquinone,namely BQ,is a kind of quenching agent that can quench the fluorescence of PFBD CPNs,then SO₃^2-is added to the system,BQ can be reduced to phenol?H₂Q?since that SO₃^2-has strong reducibility.However,H₂Q can not quench the fluorescence of PFBD CPNs,therefore the fluorescence of PFBD CPNs will be restored,namely turn-on.The restored fluorescence intensity of PFBD CPNs is proportional to the concentration of of SO₃^2-in a certain range.We developed a method for SO₃^2-detection.The detection range of the optimized method for SO₃^2-is10-300?M and the detection limit is 4?M.We then developed detection methods of Cu²⁺and glutathione?GSH?based on NPG@PFBD CPNs.Firstly,Cu²⁺is add to the NPG@PFBD CPNs system,Cu²⁺can be capturedby the NPG that located on the surface of NPG@PFBD CPNs.Then,the PET process between NPG@PFBD CPNs and Cu²⁺will lead to fluorescence quenching,the quenching mechanism can be described by the Stern-Volmer equation.This quenching process are used to establishing the detection method of Cu²⁺,linear range of the method for the detection of Cu²⁺is 0.01-10 M.At the end,we developed a detection method for GSH by adding GSH to the NPG@PFBD CPNs/Cu²⁺system.The mechanism of this process is that the-SH which come from GSH can combine Cu²⁺strongly,Cu²⁺that combined with NPG@PFBD CPNs/Cu²⁺can be captured by GSH and then the PET process between NPG@PFBD CPNs and Cu²⁺were blocked,the fluorescence intensity of NPG@PFBD CPNs therefore be restored,the recovery degree is proportional to the concentration of GSH in a certain range.The detection limit of GSH of the detection method we have established is 90nM,and the linear range is 0.25-30?M.