| Quantum dots, as its excellent fluorescent properties, has been widely used in biological engineering. After the surface modification of CdSe quantum dots, the surface with active functional groups, by the molecular coupling effect, QDs can be connected to DNA, proteins. Currently in preparation methods, quantum dots, organic synthesis had many reports, this method can obtain high efficiency fluorescent particles homogeneous quantum dots. However, in organic synthesis, there are serious problems, such as TOPO has a strong toxicity, the obtained QDs surface layer of TOPO, TOPO is not only toxic, but also hydrophobic substances, which makes the prepared quantum point does not have a water-soluble, the QDs used in the field of biology at a disadvantage.In this study, the QDs in the aqueous phase synthesis method was set up, and quantum dots by oligosaccharides molecular modification to make quantum dots can be entered HepG2 cells by cell surface lectin, and also on the toxicity in cells, QDs-Man have the advantage.(1) Aqueous-phase synthesis of quantum dots conditions:400 mg Se and 400 mg NaBH4 was added in 1ml aqueous solution,2h latter, take 0.25 ml to 90 ml aqueous solution containing 25mg of CdCl2·2.5H2O and 0.025 ml thioglycolic acid,96℃,2h, QDs was obtained, the quantum dots was tested by infrared, ultraviolet, electron microscopy and fluorescence in areas such as characterization, the results was showed that the uniform size of particles dispersed quantum dots was obtained, and the use of chitosan to coat quantum dots, quantum dots marked the drug carried molecules.(2) Quantum dots and 9 kinds of trisaccharides were connected, and the connection of products added to the HepG2 cell culture medium, then screened and found mannose modified quantum dots can entered the HepG2 cells, this result as the literature reported that HepG2 cell surface great expressed mannose lectin which could help carbohydrate molecules through cancer cells. In addition, it was found that mannose modified quantum dots on HepG2 cells showed no cytotoxicity, and still maintain a long fluorescence characteristics. It was also found mannose modification of quantum dots can also be labeled HepG2 cells byy in vivo mice tumor model.(3) Mannose modified quantum dots and quantum dots were modified with bovine serum albumin, bovine serum albumin is often used as study drug molecules in vivo pharmacology study, it was found that quantum dots which are modified by mannose, its combination with BSA significantly reduced, it was beneficial for the quantum dots in vivo toxicity studies and a supplement of the quantum dot surface modification. In addition, the quantum dots connected with bovine serum albumin was studied, it was found that quantum dots can lead to quenching, and it was a static quenching process, the molar ratio of 1:1 between them to combine. According to synchronization fluorescence spectroscopy, it can be obtained that quantum dots mainly connected with tyrosine of BSA, but not with the serine. According to Foste dipole energy transfer theory, the distance ofquantum dots connected with BSA can be calculated, it was 6.56nm, less than 8nm, it showed the combination of quantum dots and the BSA was an effective combination. The result could provide some basis information for the study of quantum dots in vivo toxicity and in vivo pharmacology.
|
PDF Full Text Request