Translocation of C₆₀ and Its Derivatives Across a Lipid Bilayer

Abstract

Obtaining an understanding, at the atomic level, of the interaction of nanomaterials with biological systems has recently become an issue of great research interest. Here we report on the molecular dynamics study of the translocation of fullerene C60 and its derivative C60(OH)20 across a model cell membrane (dipalmitoylphosphatidylcholine or DPPC bilayer). The simulation results indicate that, although a pristine C60 molecule can readily "jump" into the bilayer and translocate the membrane within a few milliseconds, the C60(OH)20 molecule can barely penetrate the bilayer. Indeed, the mean translocation time via diffusion for the C60(OH)20 molecule is several orders of magnitude longer than for the former. It was also determined that the two different forms of fullerenes, when adsorbed into/onto the bilayer, affected the membrane structure differently. This study offers a mechanistic explanation of that difference and for the reduced acute toxicity of functionalized fullerenes.

Dynamics of C60Molecules in Biological Membranes: Computer Simulation Studies

“…This result is consistent with density profile and free energy barrier as will be discussed below, and previous studies. 40,42 This was also observed in previous simulations of flat-shape carbon nanoparticle-membrane systems, although a large round-shape carbon nanoparticle tends to be located at the membrane center. 43 The fact that C 60 behaves similarly to a flat nanoparticle rather than a large round nanoparticle implies that the preferential location of nanoparticles is dependent more on their size (or molecular weight) than on their shape.…”

“…The presence of local minimum at ξ = 10 Å, not at the membrane center, is also observed in the previous simulations of nanoparticle permeation. 40,[42][43] The free energy profile of the C60 permeation when it is pulled from the membrane center toward the water phase shows the similar behavior to that when pulled from the water region in the range of ξ = 0 -15 Å: i.e., when the location of C60 is inside the membrane region. However, the free energy keeps increasing, as the particle is pulled further toward the water region.…”

“…The presence of the free energy barrier in the permeation process is in slight disagreement with the previous simulation studies. 40,42 The origin of this discrepancy can be visualized from the snapshots of the umbrella sampling as seen in Fig. 6.…”

“…However, the computational study on the effect of carbon nanoparticles on biological membranes using atomistic models has been relatively few. [40][41][42][43][44] Qiao et al 40 performed molecular dynamics simulations to study the translocation of fullerene C 60 and its derivative C 60 (OH) 20 across a DPPC bilayer membrane and reported the pristine C60 can readily penetrate into the bilayer without a barrier in contrast to C 60 (OH) 20 erene C60 through a DMPC membrane and reported much higher free energy difference of the C 60 permeation than that by Qiao et al We have also investigated the structural and dynamical effects of both round and flat shape nanoparticles on a DMPC lipid bilayer membrane or a DPPC monolayer membrane. [43][44] However, these previous atomistic computer simulation studies mainly focused on single-C60 behavior despite the fact that C 60 readily forms an aggregate called nano-C 60 in water phase.…”

Interaction of lipid vesicle with silver nanoparticle-serum albumin protein corona

“…Uptake of nanoparticles is thought-as agreed upon by a majority of the research community-to be realized via the energy-dependent biological process of endocytosis, in addition to passive diffusion and mechanical or biochemical damage in the lipid membrane induced by the trespassing nanoparticle. 1 However, despite intensive research efforts, both experimentally [11][12][13][14][15][16][17][18][19][20] and through atomistic and coarsegrained computer simulations, [21][22][23][24][25] it remains unclear and often controversial as to what extent the thermodynamic and endocytotic pathways may individually contribute to the convoluted process of nanoparticle cell uptake.…”