| Fisetin widely exists in plants, vegetables, fruits. It has anti-inflammatory, anti-tumor, anti-cancer, anti-viral, anti-radiation, anti-oxidation and anti-aging effect. Therefore, the determination of Fisetin plays an important role in clinical application.Copper ion is one of the indispensable trace element in organisms and also is a cofactor of ceruloplasmin. Copper has an effect on free radicals detoxification, catecholamine metabolism and melanin synthesis in biological body. Therefore, we propose a simple, sensitive method for determination of copper ion.In this paper we established quantitative tests of Fisetin and copper ion by synergistic sensitization effect of AgNPs and surfactants. At the same time, the interaction mechanisms are discussed using ultraviolet absorption spectroscopy, raman spectroscopy, fluorescence polarization, transmission electron microscopy, dynamic light scattering.The paper has four parts.The first part includes the analytical method of Fisetin, the analysis application of metal nanoparticles enhanced fluorescence effect and the analytical method of copper ion.In second part, we established a new method for selective determination of Fisetin by synergistic sensitization effect of AgNPs and cationic surfactant CTAB micelles. AgNPs was synthesized using sodium citrate reduction method and the average particle size of AgNPs is about 15nm. In suit synthesized CTAB micelles coated-AgNPs significantly enhanced fluorescence of Fisetin. Under optimum experimental conditions, the degree of fluorescence enhancement and Fisetin concentration have a good linear relationship, the linear range is from 5.0×10-8 to 1.0 ×10-6 mol L-1, detection limit (S/N = 3) is 1.5×10-9 mol L-1. Compared with the reported methods, this method has higher sensitivity and lower detection limit. And we have successfully used this method for the determination of Fisetin in actual sample. Mechanism researches have shown that CTAB micelles controlled the proper distance between Fisetin and metal fluorescence enhancement of AgNPs, Fisetin molecules solubilize in micelles, and combine with micelles coated-AgNPs, leading to the fluorescence enhancement of the system.The third part, the fluorescence intensity of Fisetin was enhanced by AgNPs and nonionic surfactant Triton X-100. AgNPs and nonionic surfactant Triton X-100 influence on the ability of hydroxyl radical scavenging. Researches found that:under the optimum experiment conditions, the degree of fluorescence enhancement has proportional to the Fisetin concentration, we established a sensitive new method for determination of Fisetin. Linear range is from 5.0×10-8 to 9.0×10-6 mol L-1, detection limit (S/N = 3) is 3.6×10-9 mol L-1, and this method has been successfully applied to the determination of Fisetin in actual sample. We found that AgNPs and Triton X-100 can enhance the ability of antioxidant activity and scavenging hydro xyl free radicals of Fisetin. Mechanism researches have shown that Triton X-100 and cationic surfactant CTAB has different interaction mode with AgNPs-Fisetin, nonionic surfactant micelles cause the aggregation of AgNPs by hydrophobic effect, Fisetin molecules solubilize in nonionic surfactant micelles, and interact with AgNPs, leading to fluorescence enhancement of the system.In the fourth part, Cu2+ has the fluorescence quenching effect of AgNPs-CTAB-Fisetin, we established a sensitive fluorescence analysis method for determination of Cu2+. Under the optimum experimental conditions, the degree of fluorescence quenching and Cu2+ concentration has a good linear relationship within a certain range, the linear range is from 7.0×10-8 to 1.0×10-6 mol L-1, detection limit (S/N = 3) is 2.1×10-8 mol L-1. Compared with the reported many methods, this method has higher sensitivity and lower detection limit. Mechanism studies show that the Cu2+ can significantly quenched the fluorescence of AgNPs-Fisetin-CTAB, Cu2+ interacts with 3-hydroxyl-4-carbonyl of Fisetin and they form a non-luminous complexe, leading to the fluorescence quenching of Fisetin.The main characteristic of this thesis:1. The study found that metal fluorescence enhancement effect of AgNPs and sensitization effect of CTAB micelles synergetic enhanced fluorescence of Fisetin. Fisetin molecules solubilized in CTAB micelles and coupled with CTAB micelles coated -AgNPs. CTAB micelles can control the proper distance between Fisetin and AgNPs.2. We studied Triton X-100 and CTAB have different interaction mode with Fisetin-AgNPs, and we also study the AgNPs and Triton X-100 have an effect on the ability of antioxidant activity and scavenging hydroxyl free radicals of Fisetin.3. Cu2+ can quench the fluorescence of Fisetin-AgNPs-CTAB, Cu2+ interacts with 3-hydroxyl-4-carbonyl of Fisetin and form a non-luminous complexe, leading to the fluorescence quenching of Fisetin. |
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