Insights into the effect of combustion-generated carbon nanoparticles on biological membranes: A computer simulation study
Insights into the effect of combustion-generated carbon nanoparticles on biological membranes: A computer simulation study
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DOI：
10.1021/jp0565148
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发表时间：
2006-03-16
影响因子：
3.3
通讯作者：
Violi, A
中科院分区：
文献类型：
--
作者：
Chang, R;Violi, A
对燃烧生成的碳纳米颗粒和脂类双层的原子模型进行了经典的分子动力学模拟，以探索它们对生物膜可能的结构、动力学和热力学效应。对于燃烧源产生的不同形貌的碳纳米颗粒，采用德雷丁泛力场，对双肉豆蔻基磷脂酰胆碱(DMPC)双层膜采用联合原子模型。观察到颗粒的形状和结构对颗粒的溶剂化、迁移率、吸附和渗透行为有显著的影响。长径比接近1的燃烧生成的碳纳米颗粒倾向于停留在膜中心附近，而其他形状的前体大多位于膜的碳氢化合物尾部区域。碳纳米颗粒不会被困在局部区域，甚至不会被困在膜内，而是根据它们的分子量自由移动。由于水分子的弱分离效应是吸附行为的主要驱动力，因此颗粒在生物膜表面的吸附与热波动相当。前驱体越大，它们与膜表面结合的强度越大。膜内燃烧生成的纳米颗粒的存在会将邻近的脂质分子推离纳米颗粒，从而扰乱局部的脂质密度。这一点，再加上温度波动，可能会导致瞬间的膜孔，从而允许水伸出。通过伞状取样方法，还得到了碳纳米颗粒渗透到双层膜的平均作用力势。令人惊讶的是，与圆形粒子相比，细长粒子的自由能垒要小一个数量级。此外，由于水分子的局部捕获，圆形碳纳米颗粒表现出很强的滞后效应。尽管本研究中研究的碳烟前体不是众所周知的碳纳米颗粒，如富勒烯或碳纳米管，但本研究的定性特征可能也适用于它们。
Classical molecular dynamics simulations of atomistic models of combustion-generated carbon nanoparticles and lipid bilayers have been performed to explore their possible structural, dynamical, and thermodynamic effects on biological membranes. The DREIDING generic force field is used for the carbonaceous nanoparticles of different morphologies, as produced from combustion sources, and the united atom model was employed for the dimyristoylphosphatidylcholine (DMPC) bilayer. It is observed that particle shape and structure have significant effects on solvation, mobility, adsorption, and permeation behavior of the particles. While combustion-generated carbon nanoparticles with an aspect ratio close to unity prefer to stay near the membrane center, precursors with other shapes mostly reside within the hydrocarbon tail region of the membrane. Carbon nanoparticles are not trapped in a local region even inside the membranes but move freely with a speed depending on their molecular weight. The adsorption of the particles on the surface of the biological membrane is comparable to thermal fluctuations because the weak segregation effect by water molecules is the main driving force to the adsorption behavior. The bigger the precursors are, the strongrer they are bound to the membrane surface. The presence of combustion-generated nanoparticles inside the membrane perturbs local lipid density by pushing the neighboring lipid molecules away from the nanoparticles. This, coupled with thermal fluctuations, can induce an instantaneous membrane pore to allow water protrusion. From the umbrella sampling method, the potential of mean force for the permeation of carbona nanoparticles into the bilayer was also obtained. Surprisingly, elongated particles have a free energy barrier an order of magnitude smaller compared with more round ones. In addition, the round carbon nanoparticles showed strong hysteresis due to the local trapping of water molecules. Although the carbon soot precursors studied in this work are not the well-known carbon nanoparticles such as fullerenes or carbon nanotubes, the qualitative features of this study may be applicable to them as well.