Penetration of C-60 into lung surfactant membranes: Molecular dynamics simulation studies

We performed molecular dynamics simulations of the systems consisting of C-60 molecules and dipalmitoylphosphatidylcholine (DPPC) monolayer membranes to study the penetration of C-60 into lung surfactant (LS) membranes. The potential of mean force of the C-60 penetration through the LS membrane was calculated as a function of the distance of a C-60 molecule from the DPPC monolayer membrane. The free energy minimum of around 43 kcal/mol is located in the DPPC tail region, indicating that the C-60 molecules can accumulate in the LS membrane region. The energy decomposition shows the main driving force of the C-60 accumulation in the lipid tail region is the van der Waals interaction with the hydrocarbon tails of DPPC lipids. Finally, we observed that the water evaporation rate can be significantly enhanced by the accumulation of C-60 molecules in the membrane tail region.