Study On Prepared 5-fluorouracil Bonded Polymeric Micelle Drug Delivery Systems For Antitumor Activity

Biodegradable nanoparticles as one of the polymeric drug carriers have proven to be useful in drug delivery. Especially, polymeric micelles are currently recognized as one of the most promising modalities of drug carriers. Polymeric micelles are supramolecular nanoparticles and have a core-shell unique structure that offer considerable advantages for cancer diagnosis and therapy, including improved antitumor efficacy, prolonged blood circulation times, reduced toxicity to healthy tissues and higher payload capacity.The polymer-drug conjugates(5-FU-PEG-PE) were synthesized by 5-Fluorouracil and PEG-PE which a diblock copolymer synthesizing in our laboratory, and prepared the polymer-drug micelles. This micelles were evaluated the safety through the acute toxicity test, and evaluated the pharmacodynamics by the tumor inhibition,and evaluated the targeting distribution in vivo through the preparation of loaded Calcein micelles. The aim of the study were to increase the drug stability, prolong the blood circulation times, reduced toxicity to healthy tissues, increase the tumor targeting and the tumor inhibition. To achieve this, the following works were done in the thesis.(1)To be saving cost, PEG-PE was synthesized through DSC condensation method by the hydrophilic polymer(PEG) and the hydrophobic polymer(PE), then using the DCC condensation method to synthesize the 5-FU-PEG-PE. The products were monitored by infrared,differential thermal analysis, and the results show that compaunds were synthesized successfully.(2)The dialysis method was chose to prepare PEG-PE and 5-FU-PEG-PE polymeric micelles. Fluorometry was used to determine the CMC with pyrene as the fluorescent probe. The size and size distribution of the micelles were measured by dynamic light scattering(DLS). The in vitro release prove that the polymeric micelles could prolong blood circulation times and increase the drug stability. The CMC values of PEG-PE,5-FU-PEG-PE were shown to be as low as 1.304×10-5 mol?L^-1 and 1.25×10-5 mol?L^-1. The size of the PEG-PE micelle was approximiately 149.6 nm,the 5-FU-PEG-PE micelle was approximiately 46.0nm and 152.3nm, those were in a narrow distribution range. Moreover, the morphology of the micelles was investigated by transmission electron microsopy(TEM). The result shows that the partical were almost spherical in shape without aggregation. In the vitro release affter 132h release nearly 94.8% demonstrated that 5-FU-PEG-PE had a long-term stability.(3)Healthy mice were treated with maximum dose of 5-FU-PEG-PE polymer micelle for only once and calculated the maximum tolerated dose. Tumor-bearing mice which was inoculated 7¹0d for liver cancer(H22) solid tumor was utilized. The mice were treated with 5-FU and 5-FU-PEG-PE respectively once a day for 5 days. Tumor inhibitory rates of each group were compared. The maximum tolerance dose of 5-FU-PEG-PE was 9.6 g·kg^-1, so the median lethal dose(LD50) must be above 9.6 g·kg^-1 which was 3.4 times 5-FU. The level of animal pharmacodynamic experiments show that the tumor inhibitory rates in high dose of 5-FU-PEG-PE was 74.71%, middle does was 68.36%. Both of those was significantly higher than 5-FU which were 66.13% and 60.61%. The result show that 5-FU-PEG-PE had good the inhibition of tumor.(4)The distribution in vivo was determeined by spectrophotofluorometer through the loaded calcein polymeric micelles. The distribution in vivo experiments showed that various organs had different time to peek through i.v. Among that heart and lung's Tmax was 15min, liver'Tmax was 1h, spleen and kdiney's Tmax was 0.5h. The content of calcein of liver tissues were the highest,and the heart were lowest. The results showed that 5-FU-PEG-PE was a potential anti-tumor drugs that can be passive targeted at liver.