We investigate the self-assembly of two telechelic star polymer–peptide conjugates based on poly(ethylene oxide) (PEO) four-arm star polymers capped with oligotyrosine. The conjugates were prepared via N-carboxy anhydride-mediated ring-opening polymerization from PEO star polymer macroinitiators. Self-assembly occurs above a critical aggregation concentration determined via fluorescence probe assays. Peptide conformation was examined using circular dichroism spectroscopy. The structure of self-assembled aggregates was probed using small-angle X-ray scattering and cryogenic transmission electron microscopy. In contrast to previous studies on linear telechelic PEO–oligotyrosine conjugates that show self-assembly into β-sheet fibrils, the star architecture suppresses fibril formation and micelles are generally observed instead, a small population of fibrils only being observed upon pH adjustment. Hydrogelation is also suppressed by the polymer star architecture. These peptide-functionalized star polymer solutions are cytocompatible at sufficiently low concentration. These systems present tyrosine at high density and may be useful in the development of future enzyme or pH-responsive biomaterials.

中文翻译：

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远螯酪氨酸末端封端的PEO星形聚合物在水溶液中的自组装

我们研究了基于聚（环氧乙烷）（PEO）四臂星形聚合物的低聚酪氨酸封端的两种遥螯星形聚合物-肽共轭物的自组装。结合物是通过N制备的PEO星形聚合物大分子引发剂的α-羧酸酐介导的开环聚合反应。自组装发生在通过荧光探针测定法确定的临界聚集浓度以上。使用圆二色谱法检查肽的构象。使用小角度X射线散射和低温透射电子显微镜探测自组装聚集体的结构。与以前的线性远螯PEO-寡酪氨酸结合物显示自组装成β-片状原纤维的研究相反，星形结构抑制了原纤维的形成，通常观察到胶束，只有在调节pH值后才能观察到少量原纤维。聚合物星形结构也抑制了水凝胶化。这些肽官能化的星形聚合物溶液在足够低的浓度下具有细胞相容性。这些系统以高密度提供酪氨酸，可用于开发未来的酶或pH响应性生物材料。