Effect of Curvature on Nanoparticle Supported Lipid Bilayers Investigated by Raman Spectroscopy
Effect of Curvature on Nanoparticle Supported Lipid Bilayers Investigated by Raman Spectroscopy
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DOI：
10.1021/jp205999p
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发表时间：
2011-11-17
影响因子：
3.3
通讯作者：
Wunder, Stephanie L.
中科院分区：
文献类型：
--
作者：
Ahmed, Selver;Nikolov, Zhorro;Wunder, Stephanie L.
利用拉曼光谱研究了1,2-二棕榈酰基-sn-甘油-3-磷酸胆碱（DPPC）和1,2-二硬脂酰-sn-甘油-3-磷酸胆碱（dsc）在二氧化硅（SiO）纳米颗粒（NPs）上的脂质堆积与它们的尺寸的关系，SiO(2) NPs的公称直径分别为5,15,25,45和100nm。使用C-C和C-H拉伸区的拉曼光谱指标来确定这些体系的构象顺序和烷基链填充。随着NP与脂质大小之比的降低，正常双层结构的包装增加了自由体积，减少了链之间的疏水相互作用。对于15、25、45和100 nm的SiO(2)，单支撑脂质双分子层（slb）在NP周围形成，拉曼数据表明，随着NP尺寸的减小，链之间的交叉作用增加，横向堆积顺序增加，这改善了疏水结合，减少了正常双分子层可能出现的空隙。对于相同大小的NP，与DPPC脂质相比，dsc的交叉和侧向堆积增加，正如预期的那样，基于更长的烷基链长度会产生更大的空隙体积。填充空隙的另一种机制是在双分子层中心的末端甲基形成间扭扭，这可以通过1122 cm（-1）的拉曼带来监测。这些间扭式缺陷在最大尺寸（100 nm）的NP中最为普遍，但在所有尺寸的NP中都可以观察到。对于形成聚集体的5nm slb，我们假设NPs之间可以发生双层桥接。与15 nm的NPs相比，序参量增加，但反式构象较少，这可能是由于链在间隙区松散排列或孤立。
The packing of lipids on silica (SiO(2)) nanoparticles (NPs) was investigated by Raman spectroscopy for 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) as a function of their size, for SiO(2) NPs of 5, 15, 25, 45, and 100 nm nominal diameter. Raman spectral indicators in the C-C and C-H stretching regions were used to determine conformational order and alkyl chain packing for these systems. As the ratio of NP to lipid size decreases, packing in a normal bilayer configuration increases free volume and decreases hydrophobic interaction between the chains. For the 15, 25, 45, and 100 nm SiO(2), for which single supported lipid bilayers (SLBs) are formed around the NPs, the Raman data indicate that there is increased interdigitation and increased lateral packing order between the chains with decreasing NP size, which improves hydrophobic association and decreases the voids that would occur for normal bilayers. For the same size NP, there is increased interdigitation and lateral packing for the DSPC compared with DPPC lipids, as expected based on the greater void volume that would be created for the longer alkyl chain lengths. Another mechanism for filling this void space is the formation of gauche kinks for the terminal methyl groups at the center of the bilayer, which can be monitored by a Raman band at 1122 cm(-1). These gauche defects are most prevalent for the largest size (100 nm) NPs but are observed for all NP sizes. For the 5 nm SLBs, which form aggregates, we hypothesize that bilayer bridging can occur between the NPs. Compared with the 15 nm NPs, the order parameter increases but there are fewer trans conformers, possibly due to chains that are loosely packed or isolated in the interstitial regions.