Cationic Gel-Phase Liposomes with "Decorated" Anionic SPIO Nanoparticles: Morphology, Colloidal, and Bilayer Properties
Cationic Gel-Phase Liposomes with "Decorated" Anionic SPIO Nanoparticles: Morphology, Colloidal, and Bilayer Properties
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DOI：
10.1021/la2011138
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发表时间：
2011-07-19
期刊：
影响因子：
3.9
通讯作者：
Bothun, Geoffrey D.
中科院分区：
文献类型：
--
作者：
Chen, Yanjing;Bothun, Geoffrey D.
带相反电荷的胶体的组装和络合是许多天然和合成过程中的重要现象。脂质体-纳米颗粒组装体（LNAs）代表了一种有趣的混合系统，其结合了"软"和"硬"胶体材料。本工作描述了通过将阴离子超顺磁性氧化铁（SPIO）纳米颗粒与阳离子二棕榈酰磷脂酰胆碱（DPPC）/二棕榈酰三甲基铵丙烷（DPTAP）脂质体结合形成的凝胶相LNA的形成和表征。检查流体动力学直径低于（16 nm）和高于（30 nm）的颗粒，报告了支持脂质双层形成的截止值。用16 nm颗粒形成LNA是熵驱动的，并且颗粒单独结合以产生"装饰"结构。在这种情况下，增加纳米颗粒浓度产生胶体LNA聚集体和最终的电荷反转。相比之下，LNA的形成与30 nm的颗粒是螺旋驱动的，和纳米粒子聚集在双层界面。尽管脂质体表面的电荷屏蔽最小，但由于脂质体破裂，这些聚集体导致显著的LNA聚集和大的双层片。在这种情况下，存在SLB，但这些结构不是主要的。LNA结构的差异也揭示了通过脂质相变行为。这项工作推断尺寸依赖的纳米粒子的结合和LNA的形成机制，可用于定制胶体和双层性能。类比，以消除补丁电荷异质性和DNA与阳离子脂质体的络合。
The assembly and complexation of oppositely charged colloids are important phenomena in many natural and synthetic processes. Liposome-nanoparticle assemblies (LNAs) represent an interesting hybrid system that combines "soft" and "hard" colloidal materials. This work describes the formation and characterization of gel-phase LNAs formed by the binding of anionic superparamagnetic iron oxide (SPIO) nanoparticles to cationic dipalmitoylphosphatidylcholine (DPPC)/dipalmitoyltrimethylammonium propane (DPTAP) liposomes. Particles were examined with hydrodynamic diameters below (16 nm) and above (30 nm) the cutoff reported for supported Lipid bilayer formation. LNA formation with 16 nm particles was entropically driven and particles bound individually to yield "decorated" structures. In this case, increasing nanoparticle concentration yielded colloidal LNA aggregates and eventual charge inversion. In contrast, LNA formation with 30 nm particles was enthalpically driven, and the nanoparticles aggregated at the bilayer interface. These aggregates led to significant LNA aggregation and large bilayer sheets due to liposome rupture despite minimal charge screening of the liposome surface. In this case SLBs were present, but these structures were not dominant. Differences in LNA structure were also revealed through the lipid phase transition behavior. This work infers size-dependent nanoparticle binding and LNA formation mechanisms that can be used to tailor colloidal and bilayer properties. Analogies are made to polyelectrolyte patch charge heterogeneities and DNA complexation with cationic liposomes.