3D Columnar Phase of Stacked Short DNA Organized by Coherent Membrane Undulations
3D Columnar Phase of Stacked Short DNA Organized by Coherent Membrane Undulations
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DOI：
10.1021/acs.langmuir.9b01726
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发表时间：
2019-09-10
期刊：
影响因子：
3.9
通讯作者：
Safinya, Cyrus R.
中科院分区：
文献类型：
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作者：
Bouxsein, Nathan F.;Leal, Cecilia;Safinya, Cyrus R.
我们报告发现一个新的有组织的脂质核酸相插入钝双链体的短DNA（sDNA）内的阳离子多层流体膜。sDNA之间的端对端相互作用导致柱状堆叠。在高膜电荷密度下，在sDNA柱间间距（d（sDNA））相当但大于sDNA直径的情况下，2D柱状相（即，2D近晶相）类似于具有长噬菌体DNA的阳离子脂质体-DNA复合物中的相。值得注意的是，随着d（sDNA）随着膜电荷密度降低而增加，观察到向堆叠的sDNA的3D柱状相的转变。即使通过在sDNA的磷酸基团附近扩散阳离子脂质来筛选跨层的直接DNA-DNA静电相互作用，也会发生这种情况。软化的膜弯曲刚度（卡帕），这进一步促进膜的起伏，显着提高了三维柱状相。这些观察结果与Schiessel和Aranda-Espinoza的模型一致，其中由于静电诱导的膜缠绕在sDNA柱周围，局部膜波动从层到层锁相，从而沉淀与具有长程位置和取向顺序的sDNA柱耦合的相干“晶体样”波动。该新相在大d（sDNA）下稳定并且随着kappa降低而增强的发现进一步支持了模型，其中sDNA柱周围每单位面积的膜变形的弹性成本（与kappa h（2）/d（sDNA）（4）成比例，h（2）=内部和外部单层波动幅度的平方和）相对于围绕sDNA柱的部分包裹的膜的有利静电吸引，这一发现对3D膜介导的功能纳米颗粒组装的设计具有广泛的意义。
We report on the discovery of a new organized lipid-nucleic acid phase upon intercalation of blunt duplexes of short DNA (sDNA) within cationic multilayer fluid membranes. End-to-end interactions between sDNA leads to columnar stacks. At high membrane charge density, with the inter-sDNA column spacing (d(sDNA)) comparable but larger than the diameter of sDNA, a 2D columnar phase (i.e., a 2D smectic) is found similar to the phase in cationic liposome-DNA complexes with long lambda-phage DNA. Remarkably, with increasing d(sDNA) as the membrane charge density is lowered, a transition is observed to a 3D columnar phase of stacked sDNA. This occurs even though direct DNA-DNA electrostatic interactions across layers are screened by diffusing cationic lipids near the phosphate groups of sDNA. Softening of the membrane bending rigidity (kappa), which further promotes membrane undulations, significantly enhances the 3D columnar phase. These observations are consistent with a model by Schiessel and Aranda-Espinoza where local membrane undulations, due to electrostatically induced membrane wrapping around sDNA columns, phase lock from layer-to-layer, thereby precipitating coherent "crystal-like" undulations coupled to sDNA columns with long-range position and orientation order. The finding that this new phase is stable at large d(sDNA) and enhanced with decreasing kappa is further supportive of the model where the elastic cost of membrane deformation per unit area around sDNA columns (proportional to kappa h(2)/d(sDNA)(4), h(2) = sum of square of amplitudes of the inner and outer monolayer undulations) is strongly reduced relative to the favorable electrostatic attractions of partially wrapped membrane around sDNA columns. The findings have broad implications in the design of membrane-mediated assembly of functional nanoparticles in 3D.