文献：使用原子力谱法评估束缚1-棕榈酰-2-油酰-sn-甘油-3-磷酸胆碱膜的杨氏模量

链接：https://pubs.acs.org/doi/abs/10.1021/jp505451h

作者：王曦，罗伯特·N·桑德森‡雷吉娜·拉根

摘要：

将由浓度在0 mol %至24 mol %之间的1-棕榈酰-2-油酰-sn-甘油-3-磷酸胆碱 (POPC) 和不同浓度的1,2-二硬脂酰-sn-甘油-3-磷酸乙醇胺-N-聚乙二醇-2000- N- [3-(2-吡啶基二硫代)丙酸酯] (DSPE-PEG-PDP) 组成的单层囊泡组装在原子级平整的模板剥离金 (TS Au) 表面。使用原子力显微镜 (AFM) 对缓冲液中所得束缚脂质双层膜 (tLBM) 进行力谱分析，提供了关于机械响应随束缚分子 DSPE-PEG-PDP 浓度变化的信息。

杨氏模量通过使用最近修改的 Sneddon 模型拟合力-压痕曲线来确定，该模型校正了来自下方基质的贡献。在低浓度下，杨氏模量低于支持的 POPC LBM（即直接位于固体基底上）。模量的降低归因于膜流动性的增加，因为通过掺入 DSPE-PEG-PDP 束缚基团，tLBM 和固体基底之间的耦合减少了。从测定的杨氏模量值可知，浓度高于 6 mol % 时，PEG 链构象决定 tLBM 的刚性。AFM 力谱数据分析表明，聚乙二醇 (PEG) 蘑菇到刷子的转变发生在 6 mol % 附近，这导致 tLBM 在更高的 DSPE-PEG-PDP 浓度下先变软，然后突然变硬，这与转变有关。当 DSPE-PEG-PDP 浓度增加到 24 mol % 时，AFM 形貌和杨氏模量似乎与另一个相变相关； AFM 形貌图像与双层盘结构一致，其中 DSPE-PEG-PDP 隔离在盘的边缘。

Abstract

Unilamellar vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) with varying 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-poly(ethylene glycol)-2000-N-[3-(2-pyridyldithio) propionate] (DSPE-PEG-PDP) concentration between 0 mol % and 24 mol % were assembled on atomically flat template-stripped gold (TS Au) surfaces. Force spectroscopy, using an atomic force microscope (AFM), of the resulting tethered lipid bilayer membranes (tLBMs) in buffer provided information regarding mechanical response as a function of tethering molecule, DSPE-PEG-PDP, concentration. Young’s modulus was determined by fitting the force–indentation curve with a recently modified Sneddon model that corrects for contributions from the substrate underneath. At low concentrations, Young’s modulus is lower than that of a supported POPC LBM, i.e., directly sitting on a solid substrate. The decrease in modulus is attributed to increased membrane fluidity as coupling between the tLBM and solid substrate is reduced by the incorporation of DSPE-PEG-PDP tethering groups. From the determined Young’s modulus values, the PEG chain conformation is found to dominate tLBM rigidity at concentrations above 6 mol %. Analysis of AFM force spectroscopy data indicates that the poly(ethylene glycol) (PEG) mushroom to brush transition occurs near 6 mol %, and this leads to first softening and then abrupt stiffening of tLBMs at higher DSPE-PEG-PDP concentration associated with the transition. When DSPE-PEG-PDP concentration is increased to 24 mol %, AFM topography and Young’s modulus appear correlated with another phase transition; AFM topography images are consistent with a bilayer disk structure with DSPE-PEG-PDP segregated at the rim of the disk.

西安齐岳生物提供相关产品：

DSPE-PEG-Cy5.5

DSPE-PEG-Cy7

DSPE-PEG-NBD

DSPE-PEG-TRITC

DSPE-PEG-Comarin

DSPE-PEG-ICG

DSPE-PEG-Pyrene

DSPE-PEG-Ce6

DSPE-PEG-Cy3

以上文章内容来源各类期刊或文献，如有侵权请联系我们删除！