| Quantum dots were widely used in biology because of their unique physical and chemical properties and the basic effects of nanomaterials.The quantum dots synthesized by aqueous phase systems were characterized by low cost,simple operation and good biocompatibility,and can be directly applied to biological systems.In recent years,the research of quantum dots had developed rapidly,and it would become popular material in the field of nano research.In this paper,thioglycolic acid was used as a stabilizer to synthesize water-soluble CdSe/CdS quantum dots with high fluorescence intensity in aqueous phase system.Related biological research was carried out.The first part,literature review.This chapter introduced the basic concepts of quantum dots and the types,structures and main characteristics of quantum dots,synthesis methods,surface modification,and briefly describes the toxicity study of quantum dots and its applications in biomedicine,food safety testing,environmental science,etc.The results of applied research addressed the significance of this paper.The second part,the interaction between water-soluble CdSe/CdS quantum dots and four proteins.CdSe/CdS quantum dots were synthesized in aqueous solution with thiolacetic acid as the stabilizer.It was characterized by ultraviolet-visible absorption spectrum and fluorescence spectrum.The ultraviolet absorption spectrum indicated that there was a characteristic absorption peak at 470 nm of CdSe/CdS quantum dots.Fluorescence spectrum scanning revealed that there was a emission peak at about 650 nm of CdSe/CdS quantum dots.The interaction between CdSe/CdS quantum dots and pepsin,lysozyme,human serum albumin and protease K was studied by ultraviolet-visible absorption spectrum,fluorescence and synchronous fluorometry.The ultraviolet absorption spectra showed that the absorption spectra of the four proteins changed correspondingly in peak shape and peak position.The fluorescence spectrum results showed that the addition of CdSe/CdS quantum dots could regularly quench the endogenous fluorescence of the four proteins.Fluorescence spectroscopy results showed that the addition of CdSe/CdS quantum dots can regularly quench the endogenous fluorescence of four proteins.The interaction between CdSe/CdS quantum dots and pepsin,lysozyme and human serum albumin was static quenching.The mechanism of the interaction with proteinase K was caused by molecular diffusion and dynamic collision.The main interaction forces between CdSe/CdS quantum dots with lysozyme were hydrogen bond and van der Waals force,while the main interaction forces between CdSe/CdS quantum dots and pepsin and human serum albumin were electrostatic attraction.Based on Forster’s non-radiative energy transfer theory,the binding distance between CdSe/CdS quantum dots and these four proteins was less than 7 nm.The effects of CdSe/CdS quantum dots on the activities of pepsin,lysozyme and proteinase K were also investigated.The results showed that within a certain concentration range,CdSe/CdS quantum dots could activate the enzyme activity of lysozyme,but inhibit the enzyme activity of pepsin and proteinase K,and the higher the concentration of CdSe/CdS quantum dots,the stronger the inhibitory effect.The third part,study on the antibacterial effect of water-soluble CdSe/CdS quantum dots.In this chapter,CdSe/CdS quantum dots were applied to two kinds of bacteria,namely,Micrococcus lysodeikticus and Bacillus subtilis,and the bacteriostasis ability of CdSe/CdS quantum dots was studied from the time of action and the concentration of CdSe/CdS quantum dots.The results showed that CdSe/CdS quantum dots had good bacteriostatic effect on both bacteria.The fourth part,the effects of water-soluble CdSe/CdS quantum dots on human peripheral blood lymphocytes.In this chapter,the effects of water-soluble CdSe/CdS quantum dots on the micronucleus rate of human peripheral blood lymphocytes were investigated in vitro.The results of micronucleus test showed that the presence of CdSe/CdS quantum dots had little effect on the growth of lymphocytes in the concentration range studied.After the CdSe/CdS quantum dots acted on the cells,the micronucleus rate increased and no chromosome aberration was found.It indicated that the influence of CdSe/CdS quantum dots on cell chromosomes was small,which indicated that it has little effect on the process of human peripheral blood lymphocyte division. |
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