Using EPR To Compare PEG-branch-nitroxide "Bivalent-Brush Polymers" and Traditional PEG Bottle-Brush Polymers: Branching Makes a Difference
Using EPR To Compare PEG-branch-nitroxide "Bivalent-Brush Polymers" and Traditional PEG Bottle-Brush Polymers: Branching Makes a Difference
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DOI：
10.1021/ma301874d
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发表时间：
2012-10-23
期刊：
影响因子：
5.5
通讯作者：
Johnson, Jeremiah A.
中科院分区：
文献类型：
--
作者：
Burts, Alan O.;Li, Yongjun;Johnson, Jeremiah A.
聚乙二醇（PEG）附着在聚合物纳米结构上是一种空间屏蔽和赋予疏水有效载荷水溶性的一般策略。在这篇报告中，我们描述了直接接枝聚合，具有PEG结构域和疏水性氮氧化物结构域的分支，多功能的大单体。电子顺磁共振（EPR）光谱用于表征这些新型纳米结构内的微环境。对氮氧标记共聚物、传统瓶刷随机共聚物和嵌段共聚物进行了比较。我们的研究结果表明，与类似组成的无规共聚物相比，二价瓶刷聚合物具有更大的微观结构均匀性。此外，我们发现与传统的刷状聚合物相比，支刷状聚合物的“伪交替”结构为核结合的氮氧化物提供了更大的旋转自由度，并对外部试剂有更大的空间屏蔽作用。这一结果将对多价瓶刷材料作为生物纳米支架的进一步发展产生影响。
Attachment of poly(ethylene glycol) (PEG) to polymeric nanostructures is a general strategy for sterically shielding and imparting water solubility to hydrophobic payloads. In this report, we describe direct graft-through polymerization of branched, multifunctional macromonomers that possess a PEG domain and a hydrophobic nitroxide domain. Electron paramagnetic resonance (EPR) spectroscopy was used to characterize microenvironments within these novel nanostructures. Comparisons were made to nitroxide-labeled, traditional bottle-brush random and block copolymers. Our results demonstrate that bivalent bottle-brush polymers have greater microstructural homogeneity compared to random copolymers of similar composition. Furthermore, we found that compared to a traditional brush polymer, the branched-brush, "pseudo-alternating" microstructure provided more rotational freedom to core-bound nitroxides, and greater steric shielding from external reagents. The results will impact further development of multivalent bottle-brush materials as nanoscaffolds for biological applications.