超声/ROS双响应型自携氧纳米粒子的制备及其用于癌症“化疗-声动力协同治疗”的研究

The therapeutic efficacy of chemo-sonodynamic nano-therapeutics in hypoxic solid tumor is hampered by the challenges such as insufficient oxygen levels within the hypoxic tumor microenvironment and their uncontrolled drug release behaviors. To address these issues, a type of ultrasound/ROS dual responsive and oxygen-self-produced core-shell hybrid nanoparticles will be developed in this project. These nanoparticles are composed of a poly(amino-acid) core established from the ultrasound/ROS dual responsive polymer zinc phthalocyanine-poly(methionine-co-(aspartate-g-tetrahydro-2H-pyran-2-ol) (ZnPc-P(Met-g-Asp(THP)) and a lipoid shell modified with fluorocarbon-chains. After encapsulating the anticancer drug doxorubicin into the poly(amino acid) core, the nanoparticles would be used for the combined chemotherapy and sonodynamic therapy against hypoxic tumors, by taking the following advantages: firstly, tumor tissues can be well-oxygenated via oxygen-transportation by fluorocarbon-chains in the lipoid shell. Secondly, note that sonodynamic therapy embraces characteristics of ultrasound irradiation and massive ROS generation, so fast and targeted drug release can be achieved as a combinatory result of the ultrasound-sensitivity of tetrahydropyranal acetal bearing aspartate and the ROS-responsive property of thioether in methionine. Thirdly, the modification of nanoparticles by acetazolamide can facilitate their accumulation in the carbonic anhydrase IX (hypoxic marker) overexpressed hypoxic tumors, leading to the further enhanced synergistic therapeutic efficiency. Therefore, this study will pave an innovative path for enhancing the therapeutic efficacy of the chemo-sonodynamic nano-therapeutics against hypoxic tumors and provide theoretical and practical basis for developing more efficient synergistic nano-therapeutics.

利用纳米运载体负载药物进行“化疗-声动力协同治疗”作为一种新型无创的肿瘤协同治疗策略已受到临床研究的极大关注，但其在治疗缺氧实体瘤时，仍存在氧来源匮乏及药物控释能力不足等缺点。因此，本项目将通过乳化法制备一种以超声/ROS双响应型聚氨基酸材料酞菁锌-聚(甲硫氨酸-(天冬氨酸-g-四氢吡喃)为核，以经氟碳链修饰的类脂质为壳的复合型纳米粒子，并通过负载化疗药物，用于缺氧肿瘤的“化疗-声动力协同治疗”。首先，利用氟碳链良好的携氧能力实现肿瘤增氧，并结合声动力治疗需使用超声且产生ROS的特点，通过四氢吡喃缩醛化天冬氨酸的超声响应性及甲硫氨酸中硫醚的ROS响应性实现化疗药物的控制释放。此外，通过对该纳米粒子修饰可靶向肿瘤缺氧标记物碳酸酐酶 IX的乙酰唑胺，改善纳米粒子对缺氧肿瘤的靶向效率，从而进一步提高缺氧肿瘤的“化疗-声动力协同治疗”效果，并为新型协同治疗纳米药物的开发提供一定的理论与研究基础。

“化疗-声动力协同治疗”纳米粒子用于缺氧实体肿瘤的治疗时存在氧来源匮乏且药物控释能力不足等缺点，从而导致其对缺氧肿瘤的治疗效果往往不佳。因此，本项目制备了一种温度/ROS双响应型纳米胶束，并同时包载富氧型声敏剂及化疗药物阿霉素（DOX），实现了对缺氧肿瘤的高效“化疗-声动力协同治疗”。首先，结合超声热效应及声动力治疗中可产生大量ROS的特点，合成一类兼具温度及ROS双响应性的两亲性高临界相转变温度（UCST）聚合物乙酰唑胺-聚乙二醇-聚（丙烯酰胺-丙烯腈-单硫化二丙稀）（AZ-PEG-PAAA）用于胶束的制备，利用材料中硫醚结构经ROS氧化后所导致的材料亲疏水性变化直接下调材料UCST，实现超声辐照后UCST聚合物载体由分子间缠绕的粒子形式转变成解离的分子形式，从而促进化疗药物的快速且精准释放。同时，通过向载体材料中引入对碳酸酐酶IX（CA IX）具有靶向作用的乙酰唑胺（AZ）基团，以提高纳米胶束对缺氧肿瘤的靶向性。此外，合成了一类富氧型声敏剂—氟碳链修饰酞菁锌（ZnPc-FC-TEG），利用氟碳链良好的携氧特性，实现肿瘤增氧，从而提高声敏剂在缺氧肿瘤的声动力活性，并进一步提高该“化疗-声动力协同治疗”纳米胶束对缺氧肿瘤的治疗效率。研究结果表明，AZ-PEG-PAAA作为载体材料可高效包载声敏剂ZnPc-FC-TEG及DOX，形成粒径约为274 nm的近球形纳米粒子，表面电位近中性。此外，该纳米药物也展现出了良好的温度/ROS双响应性，超声辐照下化疗药物DOX的释放效率显著提高。同时，经乙酰唑胺修饰的纳米药物显示出较好的缺氧肿瘤靶向能力，且负载了氟碳链修饰声敏剂后的纳米药物具有携氧功能，从而提高了其在缺氧肿瘤细胞中的声动力活性。最终，该“化疗-声动力协同治疗”纳米药物在超声辐照下可有效杀伤缺氧的4T1肿瘤细胞，并且抑制小鼠4T1皮下肿瘤的生长。此外，纳米药物展现出了良好的生物相容性。因此，该研究为新型“化疗-声动力协同治疗”纳米药物的研究及制备提供一定的理论与研究基础。