Li Liwei, Davande Hemali, Bedrov Dmitry, Smith Grant D
Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
J Phys Chem B. 2007 Apr 26;111(16):4067-72. doi: 10.1021/jp064982r. Epub 2007 Apr 3.
We have carried out atomistic molecular dynamics simulations of C60 fullerenes inside a dimyristoylphosphatidylcholine lipid bilayer and an alkane melt. Simulations reveal that the preferred position of a single C60 fullerene is about 6-7 A off of the center plane, allowing the fullerene to take advantage of strong dispersion interactions with denser regions of the bilayer. Further displacement (>8 A) of the fullerene away from the center plane results in a rapid increase in free energy likely due to distortion of the lipid head group layer. The effective interaction between fullerenes (direct interaction plus environment (bilayer)-induced interaction), measured as the potential of mean force (POMF) between two fullerenes as a function of their separation, was found to be significantly less attractive in the lipid bilayer than in an alkane melt of the same molecular weight as the lipid tails. Only part of this difference can be accounted for by the more favorable interaction of the fullerene with the relatively denser bilayer. Additionally, our POMF studies indicate that the bilayer is less able to accommodate the larger aggregated fullerene pair than isolated single fullerenes, again likely due to distortion of the bilayer structure. The implications of these effects on aggregation of fullerenes within lipid bilayer are considered.
我们对二肉豆蔻酰磷脂酰胆碱脂质双层和烷烃熔体中的C60富勒烯进行了原子分子动力学模拟。模拟结果表明，单个C60富勒烯的优选位置在偏离中心平面约6 - 7埃处，这使得富勒烯能够利用与双层较密集区域的强色散相互作用。富勒烯进一步偏离中心平面（>8埃）会导致自由能迅速增加，这可能是由于脂质头部基团层的扭曲所致。富勒烯之间的有效相互作用（直接相互作用加上环境（双层）诱导的相互作用），通过两个富勒烯之间的平均力势（POMF）作为它们间距的函数来衡量，发现在脂质双层中比在与脂质尾部分子量相同的烷烃熔体中吸引力明显更小。这种差异只有部分可以归因于富勒烯与相对更密集的双层之间更有利的相互作用。此外，我们的POMF研究表明，双层比孤立的单个富勒烯更难容纳更大的聚集富勒烯对，这同样可能是由于双层结构的扭曲。我们考虑了这些效应对脂质双层内富勒烯聚集的影响。
