The Preparation Of CdTe Quantum Dots Based On Yeast And Its Application In Cell Labels As Fluorescent Probes

Nanomaterials is regarded as the most promising material in the 21st Century,As one of nanomaterials,quantum dots(QDs)has a excellent photoelectricity properties,such as broad and continuous absorption spectra;narrower and symmetric emission spectra,adjustable;high quantum yield and long fluorescence lifetime,etc.QDs with these excellent optical properties are widely applied to the field of bio-analysis,imaging of cells and tissues mark,immunoassays and disease diagnosis.So quantum dots is expected to replace the traditional dyes and become a new type of fluorescent biological probe.Although QDs has many advantages than traditional fluorescent dyes,the preparation of QDs with low toxicity and good biocompatibility is still a technical problem,which also limits the application of QDs in biomedical field.Therefore,developing a green and moderate QDs synthesis technology to be solved.In this paper,we have done a series of work in QDs synthesis based on the yeast system and as a fluorescence probe labeled human blood lymphocytes,the main contents are as follows:First of all,this paper selected Saccharomyces cerevisiae,Pichia pastoris as the QDs synthesis system,respectively.Then discussed the optimal synthesis conditions of the two reaction system of QDs,through the single factor experiment and orthogonal experiment from the factors which are the inoculation quantity,material ratio,pH,temperature and time.The results show that:the optimal synthesis conditions of the Saccharomyces cerevisiae system of quantum dots:inoculum OD 1.2,the material ratio(A/B)of 1:3,pH 6 and 6d;the optimal synthesis conditions of pichia pastoris of the quantum dots:inoculum OD 3.0,the material ratio(A/B)of 1:3,pH 4 and 6d.Under the optimum synthesis conditions,further compared the fluorescent properties of QDs from Saccharomyces cerevisiae and Pichia pastoris reaction system,show that the position of QDs fluorescence spectroscopy are different from this two systems,the former appears at around 397nm with green and blue fluorescence,and the latter appears at around 505nm with green fluorescence.With the same concentration,the fluorescence intensity of the former is much higher than the latter one.Therfore,select Saccharomyces cerevisiae as the QDs synthesis system in the subsequent experiments.Secondly,this experiment continue to study the impact of QDs wich synthesised by Saccharomyces cerevisiae reaction system on mice leydig TM3 cells,and compared with the chemical method.The experimental results show that:under the same concentration,the influence of quantum dots by chemical synthesis method to TM3 cell proliferation is more significant,and the toxicity is higer when exposed for 48h than that exposed for 24h.With the same fluorescence intensity,the effect of QDs by chemical synthesis method to TM3 cell proliferation is more significant than QDs by yeast synthesis system.Finally,based on the interaction between QDs and antibodies,QDs were conjugated with mouse anti-human CD3 antibody and goat anti-mouse IgG.,and achieved the labeling imaging of human blood lymphocytes.The experimental results show that:the direct labeling method can be used to achieve labeling imaging on human blood lymphocytes.but can not be avoided with non-specific adsorption between QDs and the cells,and produce a certain amount of interference,Indirect labeling method can avoid the above problems,thereby greatly improved the accuracy of the cell labeling,at the same time,this method has a good stability of fluorescence,a bright fluorescent signal was still observed after 72h...