Synthesis, Modification Of Hyperbranched Polyester And Its Controlled Drug Release

Aliphatic hyperbranched polyester with terminative active group of carboxyl is synthesized using citric acid as monomer. And then it is grafted by single amino ended-polyether. The results have special molecular structure-"inside hydrophobic and outside hydrophilic".The self-aggregation behavior of modified hyperbranched polyester was studied.Then the self-aggregation of modified hyperbranched polyester is applied to release of anti-cancer drugs Lonidamine, and the contolled release of extension of Lonidamine is also explored.Hyperbranched polyester was prepared via microwave and conventional synthesis approachs.The structures of hyperbranched polyester are characterized by FT IR and NMR spectra. It was found that hyperbranched polyester can be obtained through two methods. Molecular weight and its distribution are determined by SEC. Molecular weight Mn is 2395g/mol and polydispersity index is 1.42. For two polymerization methods, the effect of amount of catalyst, polymerization time and temperature on esterification rate are examined using single-factor method. And the better preparation process is as follows:suitable reaction time for microwave method was 35min, the reaction time of conventional method differs with the kinds of catalyst, thionyl chloride system for 8h, while DCC system conventional method for 10h. At this time,esterification rate has reached maximum and maintained for longer reaction time. The amount of catalyst is the same in different polymerization methods, when reached the highest esterification rate, the corresponding amount of catalyst are:thionyl chloride 3.0mL, or DCC 2.5g, the reaction temperature is 50℃.Since the hyperbranched polyester carrys large amount of terminated carboxyl groups, it is easily grafted by single amino ended-polyether of molecular weight 2000. The solubility of hyperbranched polyester greatly increased after modification has special a structure of "inside hydrophobic and outside hydrophilic". Comparing FT IR spectra of before and after modification, it's found that PEG-NH2 can be grafted to hyperbranched polyester through the reaction between amino and carboxyl groups, using DCC as condensing agent.Micelle formation of modified hyperbranched polyester is tested by TEM. The effects of solvents, polyester concentration and temperature on micelle are investigated. The results showed that:the modified hyperbranched polyester both form micelles, and the number of micelles in DMF is more than in THF, but the micelle size is larger in THE The micelle size of the hyperbranched polyester increases with the increased of polyester concentration in THF.Then modified hyperbranched polyester are used as carrier of hydrophobic anti-cancer drugs Lonidamine. Lonidamine are included in modified hyperbranched polyester, and the cummulative release ammounts are determined by UV in different medium the maximums of drug loaded in carriers in ultra-pure water and pH 7.4, pH 10 buffer solution are 0.8594mg, 25.3147mg,5.6963mg, respectively. And the times of releasing the drug completely are 600min, 380 and 420min.