新型含叶酸靶向和荧光探针双功能高分子药物载体的研究

Double Functionalized polymeric nanoparticles containing targeting groups and fluorecence probes should be more desirable in medicine for improved diagnosis and treatment. These targeting nanoparticles deliver drugs to specific organs, tissues or cells so as to decrease their potential toxic side effects at normal sensitive sites. Furthermore, the interaction between drug carriers and cells can be studied through the fluorescence probe. Therefore, this project is about to synthesize three types of amphiphilic block copolymers. The first new type of amphiphilic block copolymers is composed of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO, Pluronic) and poly(lactic acid) (PLA), containing a targeting group (folic acid, FA) on one end (FA-Pluronic-PLA). The second new type of amphiphilic block copolymers is composed of Pluronic and PLA, containing FA and a fluorescence probe (rhodamine, Rh) on both ends (FA-Pluronic-PLA-Rh). The third type of amphiphilic block copolymers is PLA-Pluronic-PLA. The size and morphologies of nanoparticles formed from the three types of copolymers in water will be studied. The applications of obtained nanoparticles in drug delivery systems will also be explored, including the release behaivors of drug-loaded nanoparticles, in vitro and in vivo targeted behaviors of nanoparticles toward tumor cells, and the intracellular distribution of nanoparticles and so on. Through these studies, monitoring on the in vivo targeted behaviors of carriers and the interaction between drug carriers and cells is expected to be able to achieve, based on developing a new type of carrier materials containing folate target group and rhodamine probe.

接上靶向基团和荧光探针的双功能型高分子纳米粒子将对癌症等疾病的有效治疗和理论研究提供有力的帮助。因为它既可以选择性地输送药物至肿瘤等病变部位，又可以通过荧光数据来分析药物载体与细胞间的相互作用。本项目拟合成三类两亲性嵌段共聚物，分别为亲水端接上靶向基团叶酸(FA)的新型共聚物叶酸-聚(氧乙烯-氧丙烯-氧乙烯)-聚乳酸(FA-Pluronic-PLA)，两端分别接上FA和荧光基团罗丹明(Rh)的新型共聚物FA-Pluronic-PLA-Rh，和PLA-Pluronic-PLA共聚物。并研究所合成高分子材料在水中自聚集形成的纳米粒子的大小和形态，以及该纳米粒子包埋抗癌药物后的释放行为、对癌细胞的体外体内靶向行为及其在细胞内的分布情况等。通过本项目的研究，期望能在发展一类新型含叶酸靶向和罗丹明荧光探针的载体材料的基础上，实现对载体在体内靶向行为、与细胞的相互作用情况等方面的监控。

含有靶向基团和荧光探针的双功能性高分子纳米粒子，既可以选择性地将药物输送到癌症等病变位置，又可以通过荧光探针来研究纳米粒子与细胞的相互作用，因此能对癌症等疾病的有效治疗和理论研究提供有利帮助。本项目成功合成了三种叶酸修饰的嵌段共聚物叶酸-Pluronic-聚乳酸 (FA-Pluronic-PLA)，具体为FA-F127-PLA、FA-P85-PLA和FA-F87-PLA。. 包埋抗癌药物紫杉醇 (paclitaxel, PTX) 的FA-Pluronic-PLA纳米粒子由透析法配制得到。激光粒度仪和透射电子显微镜的测试结果表明，包埋PTX的FA-Pluronic-PLA纳米粒子的形态均为球形胶束，大小为185-364 nm。包埋PTX的FA-Pluronic-PLA纳米粒子的体外释放行为通过高效液相色谱法检测得到，结果显示包埋在FA-Pluronic-PLA纳米粒子内的紫杉醇在最初的11小时内快速释放，接着呈现缓慢的释放过程，最终药物释放量为60 - 85%。. 通过体外细胞毒性实验，研究了包埋紫杉醇的FA-Pluronic-PLA纳米粒子的体外靶向行为。结果显示含有FA靶向的药物载体对癌细胞的抑制率明显高于非靶向药物载体的细胞抑制率。包埋紫杉醇的FA-F127-PLA纳米粒子还被注射入OVCAR卵巢癌裸鼠肿瘤模型,以研究其体内抑制肿瘤的效果。结果显示，包埋紫杉醇的非靶向和靶向纳米粒子都显示了较好的抑制肿瘤生长的作用，而靶向FA-F127-PLA的肿瘤抑制效果比非靶向PLA-F127-PLA的更好。体外体内有效的靶向行为可能与FA-Pluronic-PLA 纳米粒子表面的FA基团和OVCAR-3细胞表面叶酸受体 (folate receptor, FR) 的特异性相互作用有关，从而使包埋PTX的FA-Pluronic-PLA纳米粒子被更为有效地传递进了OVCAR-3细胞。上述结果说明FA-Pluronic-PLA共聚物在靶向药物释放体系方面有较好的应用前景。. 本项目进一步将荧光探针罗丹明通过化学键连接在FA-Pluronic-PLA共聚物上，然后通过荧光显微镜对FA-Pluronic-PLA纳米粒子在细胞内的分布情况进行了研究。结果表明，FA-Pluronic-PLA纳米粒子主要分布在OVCAR-3细胞的细胞质中。