Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States.
Department of Chemical Engineering & Materials Science , University of Minnesota , 421 Washington Avenue SE , Minneapolis , Minnesota 55455 , United States.
J Am Chem Soc. 2019 Oct 9;141(40):15804-15817. doi: 10.1021/jacs.9b06218. Epub 2019 Sep 25.
Cellular delivery of biomacromolecules is vital to medical research and therapeutic development. Cationic polymers are promising and affordable candidate vehicles for these precious payloads. However, the impact of polycation architecture and solution assembly on the biological mechanisms and efficacy of these vehicles has not been clearly defined. In this study, four polymers containing the same cationic poly(2-(dimethylamino)ethyl methacrylate) (D) block but placed in different architectures have been synthesized, characterized, and compared for cargo binding and biological performance. The D homopolymer and its diblock copolymer poly(ethylene glycol)--poly(2-(dimethylamino) ethyl methacrylate) (OD) readily encapsulate pDNA to form polyplexes. Two amphiphilic block polymer variants, poly(2-(dimethylamino)ethyl methacrylate)--poly(-butyl methacrylate) (DB) and poly(ethylene glycol)--poly(2-(dimethylamino)ethyl methacrylate)--poly(-butyl methacrylate) (ODB), self-assemble into micelles, which template pDNA winding around the cationic corona to form micelleplexes. Micelleplexes were found to have superior delivery efficiency compared to polyplexes and detailed physicochemical and biological characterizations were performed to pinpoint the mechanisms by testing hypotheses related to cellular internalization, intracellular trafficking, and pDNA unpackaging. For the first time, we find that the higher concentration of amines housed in micelleplexes stimulates both cellular internalization and potential endosomal escape, and the physical motif of pDNA winding into micelleplexes, reminiscent of DNA compaction by histones in chromatin, preserves the pDNA secondary structure in its native B form. This likely allows greater payload accessibility for protein expression with micelleplexes compared to polyplexes, which tightly condense pDNA and significantly distort its helicity. This work provides important guidance for the design of successful biomolecular delivery systems via optimizing the physicochemical properties.
细胞内生物大分子的输送对于医学研究和治疗开发至关重要。阳离子聚合物是这些珍贵负载物的有前途且经济实惠的候选载体。然而，聚阳离子结构和溶液组装对这些载体的生物学机制和疗效的影响尚未明确界定。在这项研究中，合成并比较了四种含有相同阳离子聚（2-（二甲氨基）乙基甲基丙烯酸酯）（D）嵌段但具有不同结构的聚合物，用于货物结合和生物学性能。D 均聚物及其二嵌段共聚物聚（乙二醇）-聚（2-（二甲氨基）乙基甲基丙烯酸酯）（OD）可轻易地将 pDNA 包裹形成聚阳离子复合物。两种两亲嵌段聚合物变体，聚（2-（二甲氨基）乙基甲基丙烯酸酯）-聚（-丁基甲基丙烯酸酯）（DB）和聚（乙二醇）-聚（2-（二甲氨基）乙基甲基丙烯酸酯）-聚（-丁基甲基丙烯酸酯）（ODB），自组装成胶束，其模板 pDNA 缠绕在阳离子冠上形成胶束复合物。与聚阳离子复合物相比，胶束复合物具有更高的递药效率，通过测试与细胞内化、细胞内运输和 pDNA 解包相关的假设，进行了详细的物理化学和生物学特性分析，以确定机制。我们首次发现，胶束复合物中容纳的更高浓度的胺既刺激细胞内化又刺激潜在的内体逃逸，并且 pDNA 缠绕到胶束复合物中的物理模式，类似于染色质中组蛋白对 DNA 的压缩，以其天然 B 构象保持 pDNA 的二级结构。这可能允许与聚阳离子复合物相比，通过胶束复合物对蛋白质表达具有更大的有效载荷可及性，因为聚阳离子复合物会紧密地浓缩 pDNA，并显著扭曲其螺旋性。这项工作为通过优化物理化学性质设计成功的生物分子递药系统提供了重要指导。
