The design and synthesis of a novel multifunctional core initiator based on γ-cyclodextrin (γ-CD) functionalized with eight norbornenes is reported, and a core-first approach to make eight-arm star polymers using ring-opening metathesis polymerization is carried out by grafting-from the initiator using norbornene-functionalized hexaethylene glycol. The living nature of the polymerization was verified through chain extension of the ω-functional arms with norbornene-functionalized poly(ethylene glycol) (PEG, M_n ≈ 2 kDa) to generate water-soluble diblock brush-arm star copolymers (DBASCs) with high molar masses (M_n,NMR = 187–268 kDa) and low dispersities (Đ = 1.12–1.19). The size of the corresponding star polymers was confirmed by transmission electron microscopy and dynamic light scattering (D_h ≈ 10.0–11.0 nm). The thermal properties (e.g., T_g) of the DBASCs were determined by thermogravimetric analysis and differential scanning calorimetry, the latter of which showed well-ordered materials in the solid state (prominent T_c and T_m peaks). The long-range order and crystallinity of solid-state DBASCs was further supported by well-defined powder X-ray diffraction patterns. Lastly, since γ-CD possesses an order of magnitude greater solubility in water and enhanced drug-binding capabilities compared to that for β-CD, a representative DBASC was evaluated against healthy human umbilical vein endothelial cells (and exhibited low toxicity), and was also investigated as a delivery vehicle for the anticancer drug doxorubicin as its hydrochloride salt (DOX·HCl), resulting in greater potency against MCF-7 breast cancer cells relative to that of the free DOX·HCl treatment. The star polymers reported herein represent a new modular polymeric platform with potential applications in nanostructure self-assembly and drug delivery.

中文翻译：

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通过使用γ-环糊精和ROMP的先核/接枝方法 制备的双嵌段刷臂星形共聚物：药物递送的模块化平台†

报道了一种基于八-降冰片烯官能化的γ-环糊精（γ-CD）的新型多功能核引发剂的设计与合成，并通过开环复分解聚合反应进行了核优先制备八臂星形聚合物的研究。使用降冰片烯官能化的六乙二醇从引发剂接枝。聚合反应的活性质通过用降冰片烯官能化的聚（乙二醇）（PEG，所述ω-官能臂的链延长验证中号_Ñ ≈2 kDa的），以产生水溶性的二嵌段刷臂星形共聚物（DBASCs）与高摩尔质量（M _n，NMR = 187–268 kDa）和低分散度（Đ= 1.12–1.19）。相应的星形聚合物的大小是由透射电子显微镜和动态光散射确认（d _ħ ≈10.0-11.0纳米）。热性能（例如，Ť_克）的DBASCs的通过热重量分析和差示扫描量热法，其中后者表明在固体状态下良好有序的材料（突出确定Ť _Ç和Ť_米峰）。明确定义的粉末X射线衍射图进一步支持了固态DBASC的长程有序性和结晶性。最后，由于与β-CD相比，γ-CD在水中的溶解度更高，药物结合能力增强，因此针对健康的人脐静脉内皮细胞对代表性的DBASC进行了评估（并显示出低毒性），并且还研究了作为抗癌药阿霉素盐酸盐（DOX·HCl）的传递载体，相对于免费的DOX·HCl处理，阿霉素对MCF-7乳腺癌细胞的效力更高。本文报道的星形聚合物代表了一种新型的模块化聚合物平台，在纳米结构自组装和药物递送中具有潜在的应用。