Drastic Swelling of Lipid Oligobilayers by Polyelectrolytes: A Potential Molecular Model for the Internal Structure of Lubricating Films in Mammalian Joints.
Drastic Swelling of Lipid Oligobilayers by Polyelectrolytes: A Potential Molecular Model for the Internal Structure of Lubricating Films in Mammalian Joints.
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聚电解质导致脂质双层急剧膨胀：哺乳动物关节润滑膜内部结构的潜在分子模型
DOI：
10.1021/acs.langmuir.7b03229
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
R. Dahint
中科院分区：
文献类型：
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作者：
F. Schwörer;M. Trapp;O. Soltwedel;J. Dzubiella;R. Steitz;R. Dahint
骨关节炎是西方文明中最常见的关节病。它主要是由脂质涂层软骨退化引起的，导致关节摩擦力增加。透明质酸（HA），一种带负电荷的多糖和滑液的主要成分，负责关节润滑。据信，HA吸附到脂质包被的软骨上，形成抗磨损的保护层。研究表明，在患有骨关节炎的关节中，HA的浓度和分子量（MW）降低。基于这些观察结果，HA或HA和表面活性磷脂（SAPL）的混合物的局部关节注射已被应用作为医学治疗，以在称为粘弹性补充的程序中恢复关节的功能。然而，这种治疗仍然是有争议的，并没有达成共识的最佳HA浓度和MW。为了提供详细的了解在与HA或聚合物类似物接触后的脂质膜的结构重排，我们研究了聚丙烯胺盐酸盐（PAH）与表面结合的1，2-二肉豆蔻酰-sn-甘油-3-磷酸胆碱（DMPC）的寡双层的相互作用，通过中子反射率（NR）和椭圆偏振法。使用这个模型系统，我们发现了一个激烈的肿胀的脂质膜作为PAH浓度的函数，其强度相比，在以前的研究HA孵育。与此相反，没有显着的膜厚度对PAH分子量的依赖性。开发了膜结构的详细图片，其中除其他外，显示带电PAH吸附到脂质头基，导致静电排斥。基于DLVO模型的库仑和货车德瓦尔斯相互作用平衡很好地解释了溶胀行为。我们详细的PAH/脂质界面层的结构分析可能有助于阐明粘补的机制，并推导出哺乳动物关节润滑界面的结构-功能关系。
Osteoarthritis is the most common arthropathy in western civilization. It is primarily caused by the degeneration of lipid-coated cartilage, leading to increased friction in joints. Hyaluronic acid (HA), a negatively charged polysaccharide and the main component of the synovial fluid, is held responsible for joint lubrication. It is believed that HA, adsorbed to the lipid-coated cartilage, forms a protective layer against wear. Studies have shown that the concentration and molecular weight (MW) of HA are reduced in joints suffering from osteoarthritis. On the basis of these observations, local joint injections of HA or mixtures of HA and surface-active phospholipids (SAPLs) have been applied as medical cures to restore the functionality of the joints in a procedure called viscosupplementation. However, this cure is still disputed, and no consensus has been reached with respect to optimum HA concentration and MW. To provide detailed insight in the structural rearrangement of lipid films upon contact with HA or polymeric analogues, we studied the interaction of the polyelectrolyte poly(allylamine hydrochloride) (PAH) with surface-bound oligobilayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) by neutron reflectivity (NR) and ellipsometry. Using this model system, we found a drastic swelling of the lipid films as a function of PAH concentration, whose strength compares to that in previous studies on HA incubation. In contrast, no significant dependence of film thickness on PAH MW was observed. A detailed picture of the film architecture was developed which inter alia shows that charged PAH is adsorbed to the lipid headgroups, leading to electrostatic repulsion. The swelling behavior is well explained by the equilibrium of Coulomb and van der Waals interactions in a DLVO-based model. Our detailed structural analysis of the PAH/lipid interfacial layer may help to elucidate the mechanisms of viscosupplementation and derive a structure–function relationship for the lubricating interface in mammalian joints.