基于透明质酸的智能纳米载体构建及其靶向抗肿瘤研究

Polymeric drug delivery systems with tumor-targeting ability and stimuli-sensitivity to intracellular environment can significantly improve the accuracy of drug delivery, realize drug burst release in the cancer cells, and thus sharply improve antitumor effect, which is one of the major topics in current medicine of chemotherapy. In this project, we aim to synthesize the nanospheres bearing abundant disulfide through the assembly of hyaluronic acid (HA) with tumor targeting and a derivative of cystine driven jointly by electrostatic interaction and polymerization, and large amounts of drugs would be selective released in cancer cells from the nanospheres since disulfide bonds are prone to rapid cleavage under the reductive environment inside cells. Monodisperse nanospheres with appropriate size will be controllably synthesized by in-depth studying its impact factors, which is expected to not only prolong the blood circulation time of the nanospheres for in vivo applications, but also improve the penetration depth within tumor. Compared with related reported in literature, carboxyl groups of HA acting as recongnition sites for HA receptors will not be consumed in this nanospheres for the first time. By integration of targeting capability and reduction-sensitivity, the developed multifunctional nanospheres are expected to be able to realize deliver drug to tumor site via tumor targeting and site-oriented release, and will be used to accurate therapy of cancer.

发展兼具肿瘤靶向功能和癌细胞内环境敏感的高分子药物载体，显著提高肿瘤部位给药准确性的同时实现药物癌细胞内暴释，可以急剧提升药效，是当前化疗医学发展的主要趋势。本项目拟选用有肿瘤靶向能力的透明质酸同胱氨酸衍生物，在静电驱动协同下聚合交联合成携带大量二硫键的纳米微球，对癌细胞内还原性环境敏感的二硫键将使载药微球选择性释放大量药物在癌细胞内。为延长微球体内循环时间的同时增加其瘤内渗透深度，深入研究合成影响因素以可控合成单分散的且尺寸适当的微球。本项目首次在合成纳米微球中不消耗透明质酸用作靶向位点的羧基，并将靶向功能与还原敏感性整合在一个微球上，有望实现药物对肿瘤的靶向传输和定点释放，达到准确治疗肿瘤的目标。

兼有增强药物传输和高效荧光探测功能的纳米器件是疾病诊疗试剂发展中呈现出的重要工具。本项目利用甲基丙烯酸酯化路径功能化透明质酸，合成了携带二硫键的透明质酸(HA)纳米微球。而后，通过在透明质酸微球内原位还原金盐成纳米簇生成了具有近红外荧光HA复合纳米微球。采用动态光散射、zeta电位、荧光光谱和电子显微镜技术表征了该微球及其体外刺激响应性能。了解到这些微球体现出约127 nm粒径的球形外貌，且拥有负的表面电位。荧光纳米微球的延伸探索揭示了其在水和缓冲溶液中卓越的胶体及光学稳定性。复合微球用于负载药物阿霉素，载药量约高达22%，同时包封率可达96%。体外药物释放实验揭示了该药物传输系统具有还原刺激药物释放特性，从而有利于纳米微球的体内输送药物。细胞研究表明透明质酸荧光微球可以选择性的靶向CD44和CD168过量表达的细胞，并胞吞摄入。近红外荧光成像实验证实了复合微球能够由主动及被动靶向作用在肿瘤部位有效聚积。研究表明HA荧光纳米微球拥有靶向传输抗肿瘤药物应用于癌症诊疗的巨大潜能。.为了准确评估透明质酸复合微球载药抗肿瘤效果，通过不良溶剂辅助络合法，将超顺磁性氧化铁纳米颗粒团簇限域包裹于壳聚糖内形成了粒径为200 nm的微球。壳聚糖复合微球将磁性纳米颗粒的横向弛豫率值提高了近8倍，高达533.3 Fe mM-1s-1，体现了超高的磁共振成像灵敏性。活体成像研究表明该磁性壳聚糖微球可以被动靶向富集在肿瘤内，以相对低剂量在肿瘤部位产生很高的磁共振增强造影信号。因此，这一生物相容性的磁性纳米微球作为磁共振成像造影剂，可以用于肿瘤的早期诊断和抗肿瘤治疗的实时监测。