| The metal ion-doped CdTe quantum dots are environmentally-friendly,easy to be functionalized on the surface,which improves their applicability in biological and biomedical studies with higher photo-properties and lower cell toxicity.Owing to the harsh requirements of heavy metal ions and many of the current preparation methods,Therefore,a relatively environmentally friendly synthetic method is used to construct a greener preparation route with minimal toxicity or no involvement of toxic chemical components,it is an important trend to produce quantum dots with high quantum efficiency,high yield and high reproducibility by modifying surface defects.Furthermore,the potential cytotoxicity of the metal quantum dots is not negligible,the elucidation of quantum dots genotoxicity may provide a theoretical basis for improving its biocompatibility and broadening its practical applications based on clinical diagnosis and in vivo imaging.Based on the optimization of the synthetic method of CdTe quantum dots,this paper aims to compare and analyze the structure-activity mechanism of CdTe:Zn2+QDs and DNA at molecular level by combining the research of CdTe:Zn2+QDs with the response recognition of biomolecules DNA.The binding mechanism between quantum dots and DNA have been explained.In the experiment,the antibiotic cefixime was introduced as quenching agent,and the binding mechanism of CdTe:Zn2+QDs and cefixime-DNA system was discussed in detail,which provided a reference for the development of DNA probe.The contents of this thesis are as follows:Chapter one:The current research trend of metal compounds quantum dots,the progress in the synthesis of cadmium based quantum dots and the present situation of their biological applications have been summarized.In addition,the research methods of interaction between quantum dots and DNA and the related reports and application progress of photoinduced electron transfer mechanism have been reviewed detailed.The advantages of biological application and potential toxicity of cadmium containing quantum dots are expounded.The improvement of the synthesis method of cadmium based quantum dots and the significance of their interaction with DNA are explored from various angles.Chapter two:Four kinds of CdTe:Zn2+QDs with different sizes were prepared by aqueous phase method in a pot,and the optimum reaction conditions were optimized by successive steps.The effects of different pH,coating agent and physiological buffer conditions on the photoinduced properties of CdTe:Zn2+QDs have been investigated.The optical properties,size and quantum efficiency of CdTe:Zn2+QDs have been studied and verified by means of UV spectra,fluorescence spectra,X-ray diffraction,transmission electron microscopy.Therefore,the optimal preparation conditions of CdTe:Zn2+QDs have been determined.The study in this chapter provides the basic parameters for the subsequent interaction between CdTe:Zn2+QDs and DNA.Chapter three:The quenching mechanism,interaction mode,thermodynamic parameters,conformation change of CdTe:Zn2+QDs and ctDNA under pH response were studied by means of multispectral technique and electrochemical method.The influence of different sizes of CdTe:Zn2+QDs on the system have been compared.The electrochemical impedance method is introduced for the first time to study the size effect of CdTe:Zn2+QDs with different particle sizes.The results of this chapter provides reference information for understanding the interaction mechanism between QDs and DNA at molecular level.Chapter four:A novel fluorescence reversible sensing system for CdTe:Zn2+QDs-Cefixime-ctDNA ternary system was obtained by using cefixime as quenching molecule and photoinduced electron transfer process based on CdTe:Zn2+QDs quantum dots.The interaction mechanism of CdTe:Zn2+QDs-Cefixime-DNA system was investigated by means of multispectral method,molecular docking technique,electrochemical method and atomic force microscope characterization.The causes of the formation of fluorescent reversible switches have been analyzed.The main groups of Cefixime involved in CdTe:Zn2+QDs and DNA reactions were further confirmed by infrared spectroscopy and molecular docking techniques.It can provide valuable theoretical reference for the further development of highly sensitive detection of cefixime and DNA responsive probe.Chapter five:The whole paper have been summarized,and constructive suggestions are put forward for the future research of the metal ion-doped semiconductor quantum dots. |
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