| Malignant tumor is the main disease to threaten the health and life of human being.Till now,all the conventional methods of tumor therapy have limitations.So,it is meaningful to develop a drug delivery system to target tumor cells.In this thesis a folate-mediate nano-micelles drug delivery system was studied,which was used to active target tumor cells.It provided the experimental and theoretical basis to explore a new routine of tumor therapy by drug-loaded nano-micelle system in terms of formulation,and meanwhile,provided a high efficiency and low toxicity nano-drug delivery system for poorly soluble antitumor agents.The contents of this thesis were including preparation and characterization of folate-conjugated micelle's carder materials named FA-PEG-DSPE and MPEG-DSPE, investigation of their cytotoxicity to tumor cells and the proper proportion to avoid the phagocytosis of macrophages;preparation and characterization of 9-NC-loaded folate-conjugated micelles;evaluation in vitro;pharmacokinetics experiments in rats to further prove that the ratio of FA-PEG-DSPE could effect the 9-NC-loaded micelles in vivo.The carrier materials were synthesized by dehydration-condensation reaction of carboxy group and amino group with the catalysis of DCC,and the purity that determined by HPLC was over 95%.CMC was estimated by the Pyrene method and the values of MPEG-DSPE and FA-PEG-DSPE were shown to be as low as 0.97×10 -5M and 1.0×10-5M,respectively,which suggested that the polymeric micelles had high stability and the ability to maintain the integrity even upon strong dilution.The micelles also had good biocompatibility and produced minimal cytotoxicity to tumor cells.The suitable molar ratio of FA-PEG-DSPE and MPEG-DSPE was chosen to be 1:100 as the carrier material by flow cytometry(FCM) evaluation on macrophages and active targeting ability evaluation on tumor cells with different folate content in it. The 9-NC-loaded micelles were prepared by film formation method.The formulation optimization based on entrapment efficiency,drug loading and drug concentration. The better formulation was determined as 0.5mg 9-NC and 13mL HBS buffer solution (20mg carrier materials).The micelles had a spherical shape with average size of 26.8nm.Fluorescence tracing method was applied to show that the dihydroxyfluorane was released from endosome or lysosome after folate-conjugated micelles were uptaken by tumor cells.The dihydroxyfluorane diffused to the cell nucleus gradually so that the dihydroxyfluorane was more obvious around the cell nucleus than near the cellular membrane,in order to avoid the P-gp pump.The folate free 9-NC-loaded micelles(M-9-NC) and free 9-NC were used as control preparations when 9-NC-loaded folate-conjugated micelles were studied in vitro.The results showed that the sensitivity of different kinds of tumor cells to different anticancer drugs was not the same.It showed dose and time-dependent relation.The folate-conjugated micelles could enhance the anticancer drugs with the ability of killing folate-receptor overexpressed tumor cells than M-9-NC.Pharmacokinetics experiments in rats showed that when the molar ratio of FA-PEG-DSPE and MPEG-DSPE was 0.1:100 or 1:100,the cycle time of the folate-conjugated micelles was longer than the group of 10:100.It suggested that if the molar ratio of FA-PEG-DSPE was too high,the blood circulation time would be shortened.The AUC0～t and AUC0～∞ of 0.1:100 group and 1:100 group were 2.3,1.9 times and 2.4,2.0 times,respectively,higher than those of 10:100 group.It suggested that if the folate content in the carrier materials exceeded a certain extent,it would produce adverse effect to the 9-NC folate-conjugated micelles in vivo.
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