The Research Of The Fluorescence Probe And Nano-drug Based On The L-cysteine-coated Quantum Dots

Cancer is a global health problem that is the main cause of morbidity and mortality in countries.The research and development of drugs with low toxicity,high targeting and high selectivity have become an important way in cancer treatment.The diagnosis and treatment based on nanomaterials show significant potential to better address clinical oncology problems by effectively targeting tumor cells.The unique optical properties and electronic structure make semiconductor quantum dots one of the most attractive nanomaterials widely used in biological aspects of nano-fluorescent probe and anti-tumor drug carrier.Quantum dots have the advantages of high fluorescence intensity,long fluorescence lifetime,strong light-resistant bleaching ability and high light stability.At the same time there are many deficiencies in quantum dots,such as the amount of its poor water solubility,toxicity,poor targeting of cells.We can modify the surface of the quantum dot,functional to improve its water solubility,reduce cytotoxicity,and enhance its targeting of tumor cells.Polyamines are widely distributed in the body,the biological activity of the human body has a biological regulation.Polyamines play an important role in the cell proliferation process and the division process,the polyamine derivatives increase the selectivity to tumor cells and the biological activity of the compounds.Amino acids are the basic units that make up the protein.Each amino acid molecule contains both an amino group and a carboxyl group,which can be directly linked to a nanomaterial such as a quantum dot,and then through an amide reaction to connect other drugs or groups having antitumor activity or targeting tumor cells.In this paper,the quantum dot surface is modified and functionalized to enhance the water solubility of quantum dots and its targeting of tumor cells to obtain more practical quantum dot complexes.And its fluorescence probes and nanomedicine research.The main contents of this paper are as follows:1.Three kinds of quantum dots CdSe,CdSe/ZnS,CdSe/CdS were prepared by organic phase synthesis method.we synthesized L-Cys-MPA?L-Cys-MPPDA.L-Cys-MBBDA?L-Cys-AMPDA.We can receive small particle size,good water solubility and uniform dispersion of quantum dots.Then,the modified quantum dots were characterized by transmission electron microscopy,UV absorption,fluorescence spectroscopy and infrared spectroscopy.MTT assay was performed on HeLa,SMMC-7721 and HepG2 cells respectively.The experimental results showed that the modified quantum dots had little cytotoxicity.By studying its fluorescence imaging,we found that the modified quantum dots were selective for HeLa cells and were able to target the lysosomal in the cells.2.L-Cysteine-tris(2-aminoethyl)amine was synthesized,and the three quantum dots of CdSe,CdSe/ZnS and CdSe/CdS were modified to obtain uniform dispersion and good water solubility.We found that the inhibitory rate of tumor cells was not high,and we modified the modified quantum dots to 5-fluorouracil,which greatly improved its antitumor activity.The results showed that the 5-fluorouracil could carry into the cells to inhibit the proliferation of tumor cells and induce the early apoptosis of the cells by fluorescence microscopy and flow cytometry.