Rakovska Bozena, Ragaliauskas Tadas, Mickevicius Mindaugas, Jankunec Marija, Niaura Gediminas, Vanderah David J, Valincius Gintaras
Institute of Biochemistry, Vilnius University , Mokslininku 12, Vilnius 08662, Lithuania.
Langmuir. 2015 Jan 20;31(2):846-57. doi: 10.1021/la503715b. Epub 2015 Jan 7.
Structure of the self-assembled monolayers (SAMs) used to anchor phospholipid bilayers to surfaces affects the functional properties of the tethered bilayer membranes (tBLMs). SAMs of the same surface composition differing in the lateral distribution of the anchor molecule give rise to tBLMs of profoundly different defectiveness with residual conductance spanning 3 orders of magnitude. SAMs composed of anchors containing saturated alkyl chains, upon exposure to water (72 h), reconstruct to tightly packed clusters as deduced from reflection absorption infrared spectroscopy data and directly visualized by atomic force microscopy. The rearrangement into clusters results in an inability to establish highly insulating tBLMs on the same anchor layer. Unexpectedly, we also found that nanometer scale smooth gold film surfaces, populated predominantly with (111) facets, exhibit poor performance from the standpoint of the defectiveness of the anchored phospholipid bilayers, while corrugated (110) dominant surfaces produced SAMs with superior tethering quality. Although the detailed mechanism of cluster formation remains to be clarified, it appears that smooth surfaces favor lateral translocation of the molecular anchors, resulting in changes in functional properties of the SAMs. This work unequivocally establishes that conditions that favor cluster formation of the anchoring molecules in tBLM formation must be identified and avoided for the functional use of tBLMs in biomedical and diagnostic applications.
用于将磷脂双层固定到表面的自组装单分子层（SAMs）的结构会影响拴系双层膜（tBLMs）的功能特性。具有相同表面组成但锚定分子横向分布不同的SAMs会产生缺陷程度截然不同的tBLMs，其残余电导率跨越3个数量级。由含有饱和烷基链的锚定分子组成的SAMs，在暴露于水（72小时）后，根据反射吸收红外光谱数据推断并通过原子力显微镜直接观察到，会重构为紧密堆积的簇。重排成簇导致无法在同一锚定层上建立高度绝缘的tBLMs。出乎意料的是，我们还发现，主要由（111）面组成的纳米级光滑金膜表面，从锚定磷脂双层的缺陷角度来看表现不佳，而以波纹状（110）为主的表面产生的SAMs具有更好的拴系质量。尽管簇形成的详细机制仍有待阐明，但似乎光滑表面有利于分子锚定的横向移位，导致SAMs功能特性发生变化。这项工作明确表明，为了在生物医学和诊断应用中功能性地使用tBLMs，必须识别并避免在tBLM形成过程中有利于锚定分子簇形成的条件。
