Structure and dynamics of a fluid phase bilayer on a solid support as observed by a molecular dynamics computer...

Area of Science:

• Biophysics
• Materials Science
• Computational Chemistry

Background:

• Lipid bilayers are fundamental to cell membranes.
• Interactions between lipid bilayers and solid surfaces are crucial for biosensor and biomaterial applications.
• Understanding these interactions requires atomic-level detail.

Purpose of the Study:

• To simulate the interaction between a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayer and a hydroxylated nanoporous amorphous silica surface.
• To investigate the influence of substrate-lipid distance on bilayer properties.
• To compare simulation results with experimental neutron scattering data.

Main Methods:

• Molecular dynamics simulations were employed to model the lipid-silica system.
• Simulations were conducted across various lipid-solid substrate distances.
• Forces between surfaces were qualitatively estimated.

Main Results:

• The nanoporous silica surface dynamically adjusted the water layer thickness, equalizing pressures across the bilayer.
• Estimated lipid-silicon distances from simulations closely matched neutron scattering experimental results.
• A very narrow water layer, comprising bound water molecules, was observed at the experimentally suggested separation.
• Reduced hydration minimally affected head group hydration, water orientation, and membrane dipole potential.
• Significant alterations in the lipid molecule diffusion coefficient were observed due to the silica surface.

Conclusions:

• Nanoporous silica surfaces can support lipid bilayers with dynamically adjusted hydration layers.
• While structural properties like head group hydration remain largely unaffected, the silica substrate significantly influences lipid diffusion dynamics.
• The findings provide valuable insights for designing advanced biomaterials and biosensing platforms.