多机制治疗肿瘤光热控释长循环转运系统的研究

The breast cancer as a tumor-targeted model, one novel specific antitumor delivery system, which possesses multiple therapeutic potencies (thermal therapy, tumor DNA injury, and chemotherapy) is constructed using taxol, a difficult dissolved material for an anticancer drug, water-soluble carbon nanotube derivative (CNT-PEI) for carrier matrix, glycerin monostearate for thermal hot sensitive material, phosphatidylethanolamine-PEG 2000 for a modified agent, and NGR peptide for tumor-targeting binding. The constructed complex is a long circulation delivery system of tumor target and its antitumor efficacy can be regulated by photothermal effect. The carrier has the following features: (1) loading of insoluble drug by CNT-PEI; (2) strong photothermal conversion characteristics as well as the ability to produce reactive oxygen species; (3) synergic implementation of antitumor mechanisms with chemotherapeutant; (4) reversal or partial reversal of drug resistance of tumor cells. It can make (or achieve) drug positioning quick-release when tumor site is irradiated by laser due to the thermal sensitivity of one heat-sensitive material, which encapsulates CNT-PEI and chemotherapy drug in this system. For its long circulation and characteristic of tumor targeting, the carrier is modified by PEG on the surface,and combined with NGR respectively. Further investigations in this project will be conducted optimal formulation optimization, drug release mechanism of the developed delivery system in vitro and in vivo, tumor targeting, photothermal controlled-release, distribution and its effect on tumor cells or tissues.

以乳腺癌为肿瘤模型，紫杉醇等难溶性抗癌药物为模型药，水溶性碳纳米管衍生物（CNT-PEI）为基体，单硬脂酸甘油酯等为热敏材料，PEG化磷脂为修饰剂，肿瘤靶向多肽NGR为转运系统的靶向弹头，构建具有多机制（热疗、DNA损伤和化疗）治疗肿瘤，且具有光热控释和肿瘤靶向性的长循环药物转运系统。该转运系统具有以下特点：CNT-PEI可有效荷载难溶性药物，且具有强光热转换特性以及产生活性氧能力，与化疗药物共同实现多机制治疗肿瘤作用，可（或部分）逆转肿瘤细胞耐药性；用热敏材料包封荷载化疗药的CNT-PEI，同时采用PEG修饰使其具有体内长循环特征，NGR修饰使其具有肿瘤靶向性特点。在肿瘤部位进行激光照射，由于热敏材料的热敏感性导致系统溶胀，可实现定位快速释放药物作用；课题将进行最优处方筛选和制备条件优化，药剂学特征，体内外释药机制，光控释作用，肿瘤靶向性，体内分布和对肿瘤细胞或组织的影响等进行研究。

以碳纳米管为基础，主要构建了五种多机制光热控释递药系统，并开发了这些递药系统在肿瘤成像及治疗中的应用。（1）以SWNT-PEI为基体，构建了一种NIR/pH双响应的肿瘤主动靶向控释系统。该系统可识别MCF-7细胞，具有NIR/pH双响应释药特性，使得其在正常组织的分布及释药减少，有效降低DOX的系统毒性。且可有效抑制肿瘤增殖，增加DOX半衰期，实现化疗-光热多机制协同治疗肿瘤的目标。（2）以Fe3O4-MWNTs为基体，构建了一个新型的磁靶向基因递送系统。结果证实该系统可有效递送siRNA至MCF-7细胞，实现基因沉默。通过外加磁场可实现siRNA在肿瘤部位的有效蓄积。通过核磁成像可实现MWNT-Fe3O4-PEI-PEG/siRNA在体内的可视化追踪及治疗效果监测。在808nm激光照射下，可显著抑制MCF-7细胞增殖，实现光热-基因协同治疗肿瘤的目标，提供了一个新型的肿瘤多机制诊疗体系。（3）以HA-SWNT为载体，构建肿瘤靶向Gd/HA-SWCNTs造影剂。结果显示Gd/HA-SWCNTs是一种高效、定向、缓释、低毒的MRI造影剂。基于该造影剂，通过二硫键将DOX共价连接至HA上，构建了一个具有氧化还原敏感的肿瘤主动靶向递送系统，用于药物控释及肿瘤诊疗一体化。结果表明Gd/SWCNTs-HA-ss-DOX是一个有前景的肿瘤诊疗系统，有较大潜力应用于未来临床抗癌中，以实现肿瘤靶向、化疗-光热综合治疗和MRI诊断。（4）检测了两种功能化的SWNT（SWNT-PEI和SWNT-PVPk30）在钨灯照射下的光动力学效应。结果表明， SWNT-PEI在可见光照射下还能有效产生活性氧，为开发SWNTs在肿瘤多机制治疗中的应用提供了一个新思路。（5）课题合成了一种新型碳纳米管-二氧化钛复合材料（TiO2@MWCNT）。该材料可在近红外光照射下同时实现光热转换及光动力学效应。基于此设计一种近红外光响应型凝胶局部递送系统，可实现超高的药物负载，肿瘤长效稳定释药及近红外光引发的肿瘤化疗-光热-光动力一体化综合治疗。本研究成功的完成了项目计划书中所列的各项研究计划，在该领域发表SCI论文共12篇，其中一区文章6篇，二区文章5篇。申请国家发明专利14项。依托本项目资助，培养了四名博士生和六名硕士生。