新型多电荷环糊精/多金属氧簇/酶多元纳米超分子组装体构筑及其靶向肿瘤治疗研究

It is one of the focuses of current research that the construction of novel cyclodextrin-based supramolecular systems, and their applications in the targeted cancer therapy. To improve the efficiency of chemodynamic therapy, in this project, cationic cyclodextrins will be synthesized to construct a series of binary assemblies through multi- electrostatic interactions with anionic polyoxometalates (POMs). Glucose oxidase (GOx) as the catalytic oxidant and hyaluronic acid as the targeting agent will be loaded on the binary assemblies through cyclodextrin cavities to construct pH independent multicomponent supramolecular assemblies. Various methods such as transmission electron microscope and spectral titration will be used to characterize these systems, such as the morphologies, assembly mode, load capacity of GOx and so on. The assemblies will be targetedly delivered into tumor sites then effectively deplete glucose nutrients to inhibit the proliferation, and increase the level of hydrogen peroxide (H2O2) subsequently. H2O2 would then be catalyzed into more toxic hydroxyl radical (·OH) by POMs to induce tumor cell apoptosis synergeticly. The catalytic functionalities of the assemblies for generation of ·OH will be studied by means of spectral titration and electron spin resonance. Taking breast cancer cells as the model, the targeted anti-cancer activity of the assemblies will be evaluated by flow cytometry and the anti-cancer mechanism will also be expounded. This project is of great scientific significance for further development of supramolecular chemistry and emerging therapeutic strategy.

新型环糊精纳米超分子组装体的构筑及在靶向肿瘤治疗等领域的应用是当前超分子化学研究热点之一。为提高肿瘤化学动力学治疗效率，本项目拟以多正电荷环糊精与负电荷多金属氧簇（POMs）通过多电荷静电作用构筑一系列二元组装体。利用二元组装体中环糊精空腔进一步负载葡萄糖氧化酶（GOx）作为催化氧化剂，透明质酸作为靶向剂，构筑非pH依赖多元纳米超分子组装体。采用透射电镜、光谱滴定等手段研究组装体的拓扑形貌、构筑模式、对GOx负载能力等。多元组装体靶向进入肿瘤细胞内，通过GOx氧化葡萄糖抑制肿瘤增殖并提高肿瘤组织中过氧化氢（H2O2）水平，H2O2进一步被POMs催化生成高毒性羟自由基（·OH），协同杀死肿瘤细胞。采用光谱滴定、电子自旋共振等手段研究其催化产生·OH能力。以乳腺癌细胞为模型通过流式细胞术等评价组装体靶向抗癌活性，阐述抗癌机理。该项目对于发展超分子化学及新型肿瘤治疗策略具有重要的科学意义。

本项目以正电荷的聚多巴胺嫁接的环糊精与负电荷多金属氧簇（POM）通过多电荷静电作用构筑二元组装体，利用环糊精空腔通过主客体作用负载葡萄糖氧化酶（GOx）作为催化氧化剂，透明质酸（HA）作为靶向剂，构筑级联催化的纳米超分子组装体。负载的GOx被癌细胞内化后，会消耗葡萄糖，切断营养供应，进行饥饿治疗，同时产生葡萄糖酸和H2O2进而加速POM介导的Fenton反应产生剧毒的•OH自由基，提高细胞内的ROS水平。纳米超分子组装体中POM的Mo6+消耗肿瘤组织中高浓度的GSH，破坏肿瘤的抗氧化防御系统，扩大ROS诱导的损伤。同时，纳米超分子组装体的光热效果，产生协同，增效饥饿/化学动力学的肿瘤治疗。通过对透明质酸的修饰，纳米超分子组装体可特异性聚集在肿瘤部位，提高治疗效率和安全性。体外细胞水平和荷瘤小鼠体内移植瘤的综合评价表明，纳米超分子组装体对肿瘤具有特异性的治疗效果，抑制率高达77.8%。机制研究发现，纳米超分子组装体产生ROS可以引起线粒体的损伤，进而诱发线粒体介导的细胞凋亡。同时，能够加速细胞脂质过氧化物(LPO)的累积，触发铁死亡，达到凋亡/铁死亡的协同治疗效果。且其具有较高的生物相容性、安全性和易于排泄的特点。因此，本项目基于超分子策略构建的纳米组装体在肿瘤内可触发级联反应，实现纳米催化协同治疗，为构筑基于超分子的多酶协同催化纳米反应器提供了范式，为基于光热增强的纳米级联催化肿瘤治疗提供了理论依据。