Using Cds Fluorescence Technology In Application Research Of Protein Detection In Food

Protein is the material foundation of life, it is also constitute an important part of the biological somatic tissue, and is a raw material of biological development and repair tissue. Protein plays a critical role in maintaining acid-base in human body, pass genetic information, regulating metabolism, catalytic various reaction in organisms, and etc. Its separation and the qualitative and quantitative analysis is the most important work in biochemistry and other biological disciplines, such as food inspection, clinical examination, diagnose disease, biological medicine separation,purification and quality inspection. With the progress of analysis methods unceasing, the determination method of protein content in food also procress to accurately and quickly.Utilization of fluorescence reagent or organic dyes with protein reaction, and the determination of combined with fluorescence spectrophotometry quantitative determinate protein content has a great development. This method has many characteristics, such as high sensitivity, wide linear range, low detect limit, simple and fast operation and so on, so it applies the conventional application. But as a new fluorescent reagent emergence of quantum dots, it played an important role in promoting this method research, Quantum dots have many advantages, such as broad excitation spectra and the continuous distribution, narrow and symmetric emission spectrum, spectrum can be tuned, good stability and strong resistance to bleaching, and so on. This special optical properties have great prospects in molecular biology, cell biology, genomics, drug screening, the study of biological macromolecules interactions, but using quantum dots in determination of protein content has a few studies.The aim of this dissertation is to explore simpler, more sensitive determination methods of protein, through synthetic excellent optical properties of nanometer particle, with using spectrophotometry as research means, and this method had used for sample testing. The major contents are described as follows:1. Summary of the protein determination methods, quantum dot synthesis methods and its applications in biomolecular detection is given in this part. 2. Established a fluorometry for the determination of protein: The interaction between CdS and Bovine Serum Albumin(BSA) in pH 7.50 Britton-Robinson buffer solution resulted in a fluorescence intensity of CdS increasement. This method has been applied for the determination of protein in milk and egg, and compared with the biuret method the results were satisfactory.3. Investigated variety of surfactants impact on the CdS-BSA system. The results showed that cationic surfactants such as cetyltrimethylammonium bromide (CTMAB) on the system have a significant sensitizing effect, and anionic surfactants such as sodium dodecyl sulfate (SDS) quenched, and there is milky precipitate, non-ionic surfactant such as Tween -20 effect on the fluorescence intensity of less effect. So a new method for the determination of protein was established as the reaction CTMAB with system. In pH 8.50 Boric acid-borax buffer solution, The fluorescence intensity of system increasing sensitivity after joined CTMAB into the system. The method have been used for determination of protein in food such as crushed dride pork and soybean milk. Comparing with the coomassie brilliant blue method, the results were satisfactory.4. A method for the determination of protein was established based on CdS fluorescence intensity significantly increased after CdS with BSA effect in above. But BSA with CdS effect directly can make CdS fluorescence intensity of enhanced. At the same time, its fluorescence absorption peaks shift to left, and the determination results had some effect. In this paper, the study found that first make 8-hydroxyquinoline and CdS effect(pH 8.90 boric acid-borax buffer solution), CdS fluorescence intensity significantly decreased, and the fluorescence absorption peaks move to 510nm, then added to BSA, the fluorescent absorption peaks of system were still in place of 510nm, fluorescence intensity increased significantly, and the fluorescence intensity of system is a good linear relationship with BSA concentration in certain concentration range. So a new method for the determination of protein was established. The method have been used for determination of protein in food such as crushed dride pork, chichen powder, Soybean milk powder, and so on. and compared with the Biuret method, the results were satisfactory.5. CdS nanoparticles were synthesized in aqueous solution in this experiment, and established a new method of protein determination with the CdS/ZnO fluorescence spectrophotometry. The result showed the fluorescence intensity of CdS/ZnO increased after reacted with BSA in the pH 6.10 KH2PO4-Na2HPO4 buffer solution. And the fluorescence intensity of system have good linear relationship with BSA concentration. This method have been used for determination of protein in food and urine, and compared with the coomassie briliant blue method,the results were satisfactory.6. The other research related to the issue introduced: In this experiment, ZnS nanoparticles that have special spectral properties were prepared with zinc acetate as the zinc source, sodium sulfide as sulfur source, mercaptoacetic acid as modifier by hydrothermal synthesis method. Based on the decrease of absorbance of crystal violet after ZnS reacted with crystal violet and the absorbance of system increased significantly by adding different amounts of bovine serum albumin, a new method about determination of protein was established. The method have been used for determination of protein in crushed dride pork, yoghot, and others, and compared with the coomassie brilliant blue method, the results were satisfactory.Another introduced a kind of method of determination of o-Sufobenzoic Acid Imide(Na) in the food. In Britton-Robinson (B-R) buffer solution of pH 7.00, the absorption wavelength of violet markedly increased after reacting with the o-Sufobenzoic Acid Imide(Na). In view of the above, the determination of o-Sufobenzoic Acid Imide(Na) in the food by UV spectrophotometry established. It has been used to the determination of o-Sufobenzoic Acid Imide(Na) in food, comparing with Guobiao law– HPLC, the results are satisfactory.