基于FRET效应对壳聚糖纳米载体生物清除动力学和机制的研究

纳米递药载体的生物清除（代谢和排泄）过程决定其在细胞及体内的蓄积，进而影响载体自身及递药系统的生物相容性，对该过程的深入了解是保障递药系统安全应用的工作基础。目前该领域缺乏系统的动力学研究和机制探讨。本项目以体内蓄积可能导致肝肺损伤的壳聚糖纳米粒为载体模型，区别于单荧光标记法，采用近红外量子点和荧光探针（Cy5）共同标记纳米粒，利用完整纳米粒特有的荧光共振能量转移（FRET）效应，建立纳米粒体内降解的荧光定量分析方法；对粒径50-300nm的壳聚糖纳米粒在小鼠肝肺（主要损伤器官）原代细胞及小鼠体内各组织中的清除动力学和机制进行考察；同时对载体的小鼠肝/肺清除能力与载体引起的肝/肺损伤的相关性进行探讨。本项目从细胞和机体水平详细阐述了壳聚糖纳米载体进入机体后被机体清除的完整过程和最终命运，同时揭示了载体的组织清除能力与组织相容性的关联，为壳聚糖纳米递药系统的合理设计和安全应用提供理论基础。

The biological clearance process of nano drug carriers, including metabolism and excretion processes, determines carriers’ accumulation in cells and bodies, and consequently determines the biocompatibility of nano-carriers and drug delivery systems. A thorough understanding of this process is the basis for clinical application of drug delivery systems. However, till to now few systemic research was focused on the kinetics and mechanisms of this process. In this study, chitosan nanoparticles, the accumulation of which in body might bring in hepatotoxicity and pulmonary toxicity, were selected as a model of nano-carrier. Different from the single fluorescent labeling methods applied in the previous work, the nanoparticles were labeled by the near-infrared quantum dots and fluorescent probe Cy-5 simultaneously in this study, and based on the fluorescence resonance energy transfer (FRET) effect possessed by the intact nanoparticles a quantitative fluorescent method was developed to determine the biodegradation of nanoparticle. Using this method, the biological clearance kinetics and mechanisms of chitosan nanoparticles with various diameters (50-300nm) in the primary liver/lung cells, which were the main toxicity tissues, and in different tissues of mice were studied, separately. And in this work, the relationships of liver/pulmonary carrier clearance ability and tissue toxicity induced by the carrier were studied in mice. This work elucidated the whole process and final fate of chitosan nanoparticles after being administrated in both cellular and animinal levels, and clarified the effects of tissue clearance ability on tissue toxicity induced by the nano-carrier, providing important information for the design and application of chitosan nano drug delivery systems.