Confocal Raman Microscopy Investigation of Phospholipid Monolayers Deposited on Nitrile-Modified Surfaces in Porous Silica Particles
Confocal Raman Microscopy Investigation of Phospholipid Monolayers Deposited on Nitrile-Modified Surfaces in Porous Silica Particles
复制标题
多孔二氧化硅颗粒中腈改性表面沉积的磷脂单层的共焦拉曼显微镜研究
DOI：
10.1021/acs.langmuir.0c00456
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发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Harris, Joel M.
中科院分区：
文献类型：
--
作者：
Bryce, David A.;Kitt, Jay P.;Myres, Grant J.;Harris, Joel M.
沉积在各种表面上的磷脂双分子层为研究脂质膜结构和支持生物相容性传感器提供了模型。混合支撑磷脂双分子层（hslb）是这些研究的稳定膜模型，通常是通过在烷烃修饰的表面上自组装脂质单层来制备的。制备了正烷基链改性二氧化硅hslb，并将其用于亲脂性色谱分离。这些杂化双层的结构不同于囊泡膜，囊泡膜的脂质头基团间距更大，这是由于脂质酰基链与底层的烷基链结合在二氧化硅表面上。由于脂质酰基链和与二氧化硅结合的不动烷基链之间的强相互作用，这种交错结构在较高温度下表现出更广泛的熔融转变。在目前的工作中，我们试图通过1,2-二myristoyl- cn -glycero-3-phosphocholine （DMPC）在多孔二氧化硅上的自组装来减少脂质单层与其支撑底物之间的相互作用，这些多孔二氧化硅具有腈端表面配体。脂腈界面表面- C≡N拉伸模式的拉曼散射频率与类烷烃环境一致，对脂质头基电荷不敏感，表明脂质酰基链与表面腈基接触。通过颗粒内磷脂浓度和二氧化硅比表面积测定该脂质单层的头基团面积，发现其为54±2 Å2，相当于DMPC囊泡双层的头基团面积。通过共聚焦拉曼显微镜对这些腈基支撑的磷脂单层的结构进行了表征，并发现它们与DMPC囊泡双层几乎相同。它们狭窄的凝胶到液相的熔融转变相当于分散的DMPC囊泡，这表明腈载体上的酰基链结构模拟了囊泡膜的外层小叶结构。
Phospholipid bilayers deposited on a variety of surfaces provide models for investigation of the lipid membrane structure and supports for biocompatible sensors. Hybrid-supported phospholipid bilayers (HSLBs) are stable membrane models for these investigations, typically prepared by self-assembly of a lipid monolayer over ann-alkane-modified surface. HSLBs have been prepared onn-alkyl chain-modified silica and used for lipophilicity-based chromatographic separations. The structure of these hybrid bilayers differs from vesicle membranes where the lipid head group spacing is greater due to interdigitation of the lipid acyl chains with the underlyingn-alkyl chains bound to the silica surface. This interdigitated structure exhibits a broader melting transition at a higher temperature due to strong interactions between the lipid acyl chains and the immobilen-alkyl chains bound to silica. In the present work, we seek to reduce the interactions between a lipid monolayer and its supporting substrate by self-assembly of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) on porous silica functionalized with nitrile-terminated surface ligands. The frequency of Raman scattering of the surface −C≡N stretching mode at the lipid–nitrile interface is consistent with ann-alkane-like environment and insensitive to lipid head group charge, indicating that the lipid acyl chains are in contact with the surface nitrile groups. The head group area of this lipid monolayer was determined from the within-particle phospholipid concentration and silica specific surface area and found to be 54 ± 2 Å2, equivalent to the head group area of a DMPC vesicle bilayer. The structure of these nitrile-supported phospholipid monolayers was characterized below and above their melting transition by confocal Raman microscopy and found to be nearly identical to DMPC vesicle bilayers. Their narrow gel-to-fluid-phase melting transition is equivalent to dispersed DMPC vesicles, suggesting that the acyl chain structure on the nitrile support mimics the outer leaflet structure of a vesicle membrane.