多功能药物载体表面性质与组织分布关系的研究

In this project, to enhance accumulation of multifunctional drug carriers in tumor tissue, reduce their non-specific distribution to liver and spleen in the complex physiological environment in vivo, interaction between targeting functional groups or gemini quaternary ammonium cations with cell-membrane penetration function and polyethylene glycol (PEG) on hydrophilic shells of multifunctional polyurethane micelles will be investigated, which play a key role on the hydrophilic shell surface properties of polyurethane micelles. Protein adsorption on various surfaces of polyurethane micelles and cellular uptake of these micelles by macrophages will be evaluated in vitro. Also, the in vivo biodistribution (liver, spleen) and tumor accumulation of different polyurethane micelles will be investigated using tumor-bearing mice. Ultimately, evading biological defense mechanism of multifunctional polyurethane micelles will be explored. Based on these studies, multifunctional polyurethanes will be designed and synthesized using L-lysine ethyl ester diisocyanate (LDI), L-lysine derivative peptide containing carboxyl group in side chain and gemini quaternary ammonium diamine, and L-cystine dimethyl ester as hard segment, poly(ε-caprolactone) (PCL) diols as soft segment, and hydrazone-linked methoxyl-poly(ethylene glycol)(HPEG) as end-capper, of which multifunctional micelles can escape immune clearance in vivo. And there will be very lower biodistribution in liver, spleen and other organs compared with the tumor accumulation of these drug loading multifunctional micelles in breast tumor-bearing, liver tumor-bearing, and lymphoma-bearing mice, resulting in improved biodistribution and excellent antitumor activity in vivo. These obtained results will provide an ideal targeted drug delivery system and a new approach to the design and preparation of drug carriers with multifunctional properties.

旨在提高多功能药物载体在体内复杂生理环境中在肿瘤组织的聚积，减少在肝、脾等脏器的分布，本课题提出以多功能聚氨酯药物载体为基础，研究对聚氨酯胶束亲水层表面性质起关键作用的功能基团，靶向功能基团和具有细胞穿透功能gemini双季铵盐阳离子与亲水聚乙二醇（PEG）的相互作用，从而对胶束表面性质产生影响。研究不同表面性质的聚氨酯胶束在体外抗蛋白吸附和抗巨噬细胞吞噬能力，并利用动物体内实验研究其在肝、脾、肿瘤等组织分布，揭示多功能胶束逃避生物防御顺利进入肿瘤细胞的机理。并以此为据，选用天然赖氨酸衍生的二异氰酸酯（LDI）、gemini二胺、侧链带有羧基的多肽二胺和含二硫键的胱氨酸为硬段，聚己内酯为软段，含腙键聚乙二醇单甲醚为封端剂构建能够能逃避人体免疫系统的多功能纳米载药聚氨酯胶束，以多种肿瘤模型证明其合理组织分布和良好的治疗效果。这将为新型多功能药物载体设计提供新思路和新方法，具有重要的科学意义。

通过研究多嵌段、多功能的聚氨酯胶束表面gemini季铵盐阳离子基团、MPEG亲水链段、敏感功能基团（酸敏感和氧化还原敏感）、阴离子基团、主动靶向功能基团（叶酸和抗体）相互之间的作用，对胶束结构和基本物化性能的影响，以及对聚氨酯胶束逃避免疫系统能力、细胞内化和肿瘤治疗效果的影响。获得了一些有效逃避人体免疫系统的规律：多功能、多嵌段的载药胶束自组装形成有序多层结构，功能基团间的协同效应；不同位置层次的敏感基团在生理环境中逐次断裂，使胶束表面的亲疏水和电荷发生转变；胶束表面对白蛋白的多层吸附，改善胶束表面的电位，形成伪装的亲和表面等，均可帮助药物载体逃避人体免疫系统的清除，提高抗肿瘤活性，这些研究结果为临床前系统动物实验提供了理论依据。