热化疗用靶向多功能硅质体在癌症诊治中的应用研究

Heat treatment can greatly enhance the efficiency of chemotherapy, so photothermal therapy combined with chemotherapy becomes a hot topic. However, there are two big challenge in the medicine field, one is how to use one naocarrier to co-deliver both chemotherapeutic drug and near infrared dye for combining chemotherapy with photothermal therapy; the other is how to solve the contradiction between the stability and thermal sensitivity of liposome. Herein, the applicant synthesizes a new type of hybrid lipid by covalent attachment of near infrared dye of indocyanine green derivative. Then, a multifunctional cerasome is fabricated from such hybrid lipid by self-assembly process for the encapsulation of thermalsensitive reagent of ammonium bicarbonate and chemotherapeutics of doxorubicin. On one hand, the indocyanine green derivative covalently conjugated in the lipid bilayer of cerasomes act as photothermal agent for Near infrared fluorescence imaging, photoacoustic imaging and photothermal therapy without any leaking. On the other hand, ammonium bicarbonate and doxorubicin loaded in such cerasomes can be used for controlled chemotherapy. In addition, lipids containing radionuclide chelating agent and folate targeted groups can be introduced into the cerasomes during the preparation. Thus, multifunctional nanohybrid cerasomes can be constructed with integrating different functions including targeting, high stability, controlled release, trimodal imaging (fluorescent, photoacoustic and nuclear imaging), photothermal therapy and chemotherapy, ultimately achieving the purpose of cancer therapy under the guidance of molecular imaging.

热疗能显著增强化疗疗效，将光热治疗与化疗联合已成为当前的研究热点。但是，如何使用同一载体负载化疗药物和近红外吸收染料对癌症进行化疗和光热治疗，以及如何解决脂质体稳定性和热敏性的矛盾从而实现药物的可控释放，是医药领域面临的两大挑战。申请人拟通过共价键将近红外疏水染料吲哚菁绿衍生物与脂质分子连接，合成含吲哚菁绿衍生物的复合脂质，并以此为自组装基元制备包载热敏试剂碳酸氢铵和化疗药物阿霉素的多功能硅质体。一方面，位于硅质体双层中以共价键连接的吲哚菁绿衍生物可用于近红外荧光成像、光声成像与光热治疗；另一方面，硅质体中载入的碳酸氢铵和阿霉素用于可控释化疗。在硅质体制备过程中，进一步引入含放射性核素螯合剂和叶酸靶向基团的脂质分子，这样即可得到集靶向、高稳定性、药物可控释、三模态诊断（荧光、光声和核素成像）、光热治疗与化疗于一体的新型多功能硅质体，最终达到分子成像监控下的癌症治疗目的。

本研究主要从调控药物载体稳定性和热敏性出发，设计构建硅质体药物控释系统，使光热和化疗相互增效，从而协同克服肿瘤耐药性、抑制肿瘤复发和转移。主要研究工作包括以下四个方面：1. 构建共价键连近红外染料的硅质体用于肿瘤光热-化疗联合治疗：基于共轭的甲川菁类近红外染料键连单硬脂酸甘油酯结构，设计并制备新型多功能硅质体体系，通过自组装等步骤得到具有硅酸盐表面的硅质体，与以往的光热治疗策略不同，该体系不需要释放光热剂，而是将光热剂键连在载体上，通过光照产生高热量，从而使硅质体双层膜渗透性发生改变，释放出化疗药物实现热化疗的联合；2.智能热敏硅质体通过加热产气实现局部热化疗；将硅烷前体复合脂质与近红外光热剂DiR共组装，同时包埋热敏性碳酸氢铵（ABC）和化疗药物盐酸阿霉素（DOX），构建光热敏感的硅质体药物递送系统，DiR的近红外荧光可用于指导激光照射，以实现肿瘤部位的精确热疗，同时在局部分解ABC产生CO2气泡，形成可渗透通道，促进DOX快速释放。该策略对于在肿瘤部位实现局部药物释放，减少药物过早释放，结合DiR的光热效应，可显著抑制的肿瘤的生长和复发；3. PD-L1硅质体介导的化疗和免疫治疗联合抑制肿瘤转移：构建新的以PD-L1为靶点、紫杉醇为抗癌药物、IRDye800CW荧光探针和Gd-DOTA磁共振造影剂标记的硅质体纳米粒。通过双模式荧光和核磁共振成像评估靶向特异性，并验证该药物递送体系对小鼠移植瘤的治疗效果。实验结果证实该多功能纳米硅质体可用于无创检测肿瘤中PD-L1表达的变化，以及实现靶向化疗-免疫协同治疗，有效抑制了肿瘤的转移；4. 构建近红外光热剂（DiR）-喜树碱-氟尿苷三元药物共轭体纳米胶囊，光热-化疗协同作用克服肿瘤耐药性：受硅质体稳定性启发设计合成高度对称的以共价键连接的喜树碱-氟尿苷药物共轭体，并与DiR组装，所得到的CF-DiR纳米胶囊具有很高的载药量、优异的光热转换效率、稳定的双药组合、且没有药物过早泄漏的问题，在克服肿瘤细胞多药耐药性方面具有很好的潜在应用前景。