Lipid monolayer disruption caused by aggregated carbon nanoparticles

Abstract

Carbon nanoparticles (CNP) have significant impact on the Pulmonary Surfactant (PS), the first biological barrier in the respiratory system. CNPs -abundant in the environment due to combustion -can translocate into our bodies by crossing the alveolar epithelium barrier, and they can be retained in the lungs due to slow clearance. The physical mechanisms of how CNPs perturb PS remain unclear yet such knowledge is crucial for developing effective strategies against the adverse effects of CNPs. Molecular dynamics (MD) simulations of model PS monolayers in the presence of C 60 fullerenes were performed at time scales of tens of microseconds and varying C 60 content. In contrast to bilayers, fullerenes affected both structural and dynamic properties of the PS monolayer. Surface tension/area isotherms of the monolayer were changed by fullerenes and perturbations of the physical structure of the PS monolayer became major at high fullerene concentrations due to fullerene aggregation. At high compression (area per molecule of 0.48 nm 2 ), the monolayer became unstable and collapsed forming a bilayer in the water phase. At low compression, pore formation occurred. Free energy calculations suggest that increasing fullerene concentration leads to decreased preference for the fullerenes to reside inside the monolayer.However, the free energy barrier for transferring fullerene out of the monolayer is rather large at all fullerene concentrations; spontaneous translocation of fullerene out of the monolayer is thermodynamically unfavorable. The results illustrate some of the potentially harmful effects of CNPs on the respiratory system and also the physical mechanism of how CNPs disturb pulmonary surfactant. This may be related to the difficulty of CNP clearance from lung surfactant. The total simulation time was 370 microseconds.

Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

“…The transfer of nanosized carbon-based nanoparticles from gas to aqueous phase is of utmost importance, because similar molecules-air pollutants-can reach the gas-exchange surface in the alveoli, causing various respiratory diseases. 18,19 The hydration free energy of pristine C 60 at ambient conditions was calculated recently 35,[116][117][118] on the basis of experimental C 60 -solubility in water and sublimation free energy using data by Heymann. 120 We obtain that the solvation energy of C 60 is −55.27 kJ/mol −1 at 298 K. The differences found here can be attributed to the different potentials for water and fullerene used in the simulations.…”

“…The problem of transfer of C 60 between two liquid phases-polar and non-polar-is in close relation to (i) the particle translocation across lipid membrane, 8,[13][14][15][16][18][19][20][127][128][129][130][131] which often is used as a predictor for the biological activity and (ii) partitioning of fullerenes in different solvents. 45,92,132 To this end, the change in free energy for transferring an isolated C 60 solute from water to octane is defined as ∆∆G t = −64.89 kJ/mol.…”

“…solubility, aggregation, and solvation of fullerenes are directly related to their functions in biosystems. [8][9][10][11][12][13][14][15][16][17][18][19][20] In a liquid environment-polar or non-polar-the control over the generation of fullerene clusters is a challenging multiscale problem that simultaneously involves a hierarchy of processes on very broad time and length scales. [21][22][23][24][25][26][27][28] Thus, in-depth knowledge of the origin, magnitude, and sign of solvent-mediated interaction from the molecular standpoint is of vital importance for the investigation of aggregation processes which begin on a single molecular level with the formation of a contact fullerene pair.…”

Lipid extraction mediates aggregation of carbon nanospheres in pulmonary surfactant monolayers

“…[18][19][20][21][22][23][24][25][26][27] However, due to the multi-component of PSM and environmental complexity, these results have been controversial. [18][19][20][21][22][23][24][25][26][27] However, due to the multi-component of PSM and environmental complexity, these results have been controversial.…”

Transferability of Polymer Chain Properties between Coarse-Grained and Atomistic Models of Natural Rubber Molecule Validated by Molecular Dynamics Simulations

“…All MD simulations were performed in the NPT ensemble with 300 K and 1 bar constant. The MD parameters can be seen in [5,13]. The simulations of cis-PI in solvents and melts were run for 1.5 and 6 µs, respectively.…”