Preparation and Characterization of Glycoacrylate-Based Polymer-Tethered Lipid Bilayers on Benzophenone-Modified Substrates
Preparation and Characterization of Glycoacrylate-Based Polymer-Tethered Lipid Bilayers on Benzophenone-Modified Substrates
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DOI：
10.1021/la8022997
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发表时间：
2008-12-16
期刊：
影响因子：
3.9
通讯作者：
Frank, Curtis W.
中科院分区：
文献类型：
--
作者：
Hwang, Lisa Y.;Goetz, Heide;Frank, Curtis W.
聚合物束缚的脂质双层是生物膜的有前途的模型，因为它们可以提供柔软、润滑的环境，在基质和双层之间具有足够的间距以掺入跨膜蛋白。我们提出了这样一个系统，该系统使用基于乙二醇丙烯酸酯的遥爪脂聚合物与脂质类似物的组合。空气-水界面处的脂聚合物和游离脂质的混合单层的表征用于检查决定最终组装特性的分子组织。等温线表明，主要相互作用的来源，无论是亚相中的聚合物相互作用还是烷基链相互作用，都取决于每个分子的束缚密度和面积。此外，存在一个关键的组成，在该组成中，烷基链相互作用主导单层行为，无论每个分子的面积如何。等压蠕变和滞后实验表明，当单层被压缩时，不会产生由于不可逆的聚合物-聚合物相互作用而产生的永久状态。这些数据与理论聚合物预测相结合，用于了解空气-水界面处单分子层的组织，从而了解最终双层组件的水膨胀状态下双层底部与基材之间的间隔距离。使用原子力显微镜来确认测量的 11.2 nm 的分离距离与使用代表性 5 mol% 脂聚合物系链双层的理论分析所预测的距离相当。接下来，在多个尺度上探测最终双层的均匀性。荧光显微镜用于证明本研究中使用的所有聚合物束缚密度都可以形成均匀且连续的双层（在 500 nm 的光学分辨率限制内）。原子力显微镜研究表明，对于代表性的 5 mol% 脂聚合物系链双层，可以实现与固体支持的脂质双层相当的均匀性。还讨论了沉积单层的 Langmuir-Blodgett 转移条件，可用于创建均匀的流体双层。最后，使用光漂白实验后的荧光恢复来测量远端小叶横向移动性，并显示其是束缚密度的函数。开发了一种可能的流动性数据模型，其中近端小叶中的系留脂质充当与远端小叶脂质耦合的固定脂质障碍。
Polymer-tethered lipid bilayers are promising models for biological membranes as they may provide a soft, lubricating environment with sufficient spacing between the substrate and bilayer for incorporating transmembrane proteins. We present such a system that uses a glycoacrylate-based telechelic lipopolymer in combination with a lipid analogue. Characterization of the mixed monolayers of lipopolymers and free lipids at the air-water interface is used to examine the molecular organization that dictates the final assembly properties. Isotherms indicate that the source of the dominating interactions, whether polymer interactions in the subphase or alkyl chain interactions, depends on both the tethering density and area per molecule. Moreover, a critical composition exists at which the alkyl chain interactions dominate the monolayer behavior regardless of the area per molecule. Isobaric creep and hysteresis experiments suggest that permanent states due to irreversible polymer-polymer interactions are not created as the monolayer is compressed. These data, combined with theoretical polymer predictions, are used to understand the organization of the monolayers at the air-water interface and, hence, the separation distance between the bottom of the bilayer and substrate in the water-swollen state of the final bilayer assembly. Atomic force microscopy is used to confirm that the measured separation distance of 11.2 nm is on the order of what would be predicted using a theoretical analysis for a representative 5 mol % lipopolymer-tethered bilayer. Next, the homogeneity of the final bilayer is probed at multiple scales. Fluorescence microscopy is used to demonstrate that homogeneous and continuous bilayers can be formed (within the optical resolution limit of 500 nm) with all polymer tethering densities used in this study. Atomic force microscopy studies demonstrate that homogeneity comparable to that of a solid-supported lipid bilayer can be achieved for a representative 5 mol % lipopolymer-tethered bilayer. Langmuir-Blodgett transfer conditions for depositing monolayers that can be used to create homogeneous, fluid bilayers are also discussed. Finally, the distal leaflet lateral mobility is measured using fluorescence recovery after photobleaching experiments and shown to be a function of the tethering density. A possible model for the mobility data is developed in which the tethered lipids in the proximal leaflet act as immobile lipid obstacles that couple to distal leaflet lipids.