Synthesis Of Glutathione-Capped CdTe Quantum Dots And Application In Labeling Bio-Molecule

Quantum dots as new nano-materials since 1970s showed us amazing fluorescent advantages more than organic dyes,such as broad absorption spectra,narrow emission spectra,efficient fluorescence,good photo-stability,long decay lifetime and having different colors in different sizes.All these advantages make QDs well used in physical,chemical and biological fields.In the biological area,QDs are mainly used in labeling bio-moleculars and cells, tumor detection,early diagnosis of diseases,nucleotide detection and so on.With preparation of quantum dots innovated and the surface of quantum dot optimized, quantum dots will be applied in more areas.The bio-conjugation of QDs and biological molecules is basic and used in many study works,It is foundation to further investigation.It's necessary to work on it for its further research.In this study,we synthesized glutathione capped CdTe Quantum Dots and conjugation QDs with bovine serum albumin(BSA) and DNA fragment.The main results are as follows:1.A optimized Water-phase methods to synthesis glutathione(GSH) capped CdTe quantum dots is set up.We produced red quantum dots with emission wavelength of 625 nm and a highly quantum yield of 45%.The results show that the quantum dots are like balls about 5 nm,and have good dispersion;2.We studied the interaction of BSA to CdTe-GSH quantum dots.When quantum dots concentration is 1 mmol/L and BSA concentration is 20-100 mg/L, the quantum dots' fluorescence intensity values(F-F₀)/F₀ have a linear relation between the concentration of BSA,The linear regression equation is:(F-F₀)/F₀=0.01937^* C-0.3294,correlation coefficient R=0.9949;3.We studied the covalent cross-linker EDC and NHS and Tris buffer solution,2 -mercapto-ethanol on the effects of quantum dots.Cross-linker EDC and NHS play a stronger role in quenching quantum dots,Tris buffer solution has weak effect on quantum dots,and 2-mercaptoethanol has a very strong quenching effect on quantum dots;4.Optimization of the optimal CdTe-GSH quantum dots marked BSA methods and the best reaction conditions.The results show that the method of using EDC which is mainly used as cross-linking agent to labeling quantum dots and BSA is simple and effective.The reaction agents mole ratio of CdTe-GSH quantum dots,EDC,and bovine serum albumin is 1:10:1,Quantum dots and BSA reaction at room temperature for 2 hours to achieve good labeling effect;5.We made sephadex chromatography after connecting quantum dots and BSA, the chromatography results showd that CdTe-GSH quantum dots were labelled on the bovine serum albumin;6.We labelled CdTe-GSH quantum dots to 5' end amino-modified DNA fragments,Gel electrophoresis results show that quantum dots were connected to the DNA fragments.After conjugation the fluorescence of quantum dots has been obviously enhanced,and higher concentration of DNA leads to higher fluorescence.