Nanomechanical Properties of Artificial Lipid Bilayers Composed of Fluid and Polymerizable Lipids
Nanomechanical Properties of Artificial Lipid Bilayers Composed of Fluid and Polymerizable Lipids
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DOI：
10.1021/acs.langmuir.1c02098
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发表时间：
2021-12-30
期刊：
影响因子：
3.9
通讯作者：
Saavedra, S. Scott
中科院分区：
文献类型：
--
作者：
Fonseka, N. Malithi;Arce, Fernando Teran;Saavedra, S. Scott
聚合提高了平面支撑脂双层(PSLB)的稳定性，但它也改变了其化学和机械性质，减弱了脂扩散，并可能影响完整膜蛋白的活性。由流体脂和聚脂组成的混合双层可以提供聚合物稳定性以及维持重组受体生物活性所需的流动性和弹性的适当组合。在此之前(Langmuir，2019，35,12483-12491)，我们已经证明了可聚合脂双-SorbPC和流体脂DPhPC的二元混合物形成了由纳米流体和多(脂)域组成的相分离的PSLB。在这里，我们使用原子力显微镜(AFM)来比较这些二元PSLB和单组分PSLB的纳米级机械性能。随着聚合反应的进行，双索尔贝壳的弹性(杨氏)模数、面压缩模数和弯曲模数均增加。在聚合前，在5nN以下的作用力下观察到了穿透现象，但在聚合后，当作用力达到20nN时，AFM针尖不能穿透PSLB。这些结果归因于聚(双-SorbPC)中的聚合物网络，它增加了双层的刚性，并抵抗了压缩和弯曲。在二元DPhPC/聚(bis-SorbPC)PSLB中，与纯DPhPC双层相比，DPhPC结构域不那么僵硬，更容易压缩，抗断裂和弯曲能力更差。这些差异归因于DPhPC结构域中存在的双-SorbPC单体和低聚物破坏了DPhPC分子的堆积。相反，与纯PSLB相比，聚(bis-SorbPC)结构域更坚硬，可压缩性更差；这种差异归因于DPhPC填充了在bi-SorbPC聚合过程中产生的聚合结构域中纳米级的孔洞。因此，不完全的相分离增加了聚(双-SorbPC)的稳定性，但对DPhPC却有相反的不利影响。总体而言，这些结果为工艺用部分聚合双层的设计提供了指导。
Polymerization enhances the stability of a planar supported lipid bilayer (PSLB) but it also changes its chemical and mechanical properties, attenuates lipid diffusion, and may affect the activity of integral membrane proteins. Mixed bilayers composed of fluid lipids and poly( lipids) may provide an appropriate combination of polymeric stability coupled with the fluidity and elasticity needed to maintain the bioactivity of reconstituted receptors. Previously (Langmuir, 2019, 35, 12483-12491) we showed that binary mixtures of the polymerizable lipid bis-SorbPC and the fluid lipid DPhPC form phase-segregated PSLBs composed of nanoscale fluid and poly(lipid) domains. Here we used atomic force microscopy (AFM) to compare the nanoscale mechanical properties of these binary PSLBs with single-component PSLBs. The elastic (Young's) modulus, area compressibility modulus, and bending modulus of bis-SorbPC PSLBs increased upon polymerization. Before polymerization, breakthrough events at forces below 5 nN were observed, but after polymerization, the AFM tip could not penetrate the PSLB up to an applied force of 20 nN. These results are attributed to the polymeric network in poly(bis-SorbPC), which increases the bilayer stiffness and resists compression and bending. In binary DPhPC/poly(bis-SorbPC) PSLBs, the DPhPC domains are less stiff, more compressible, and are less resistant to rupture and bending compared to pure DPhPC bilayers. These differences are attributed to bis-SorbPC monomers and oligomers present in DPhPC domains that disrupt the packing of DPhPC molecules. In contrast, the poly(bis-SorbPC) domains are stiffer and less compressible relative to pure PSLBs; this difference is attributed to DPhPC filling the nm-scale pores in the polymerized domains that are created during bis-SorbPC polymerization. Thus, incomplete phase segregation increases the stability of poly(bis-SorbPC) but has the opposite, detrimental effect for DPhPC. Overall, these results provide guidance for the design of partially polymerized bilayers for technological uses.