Asymmetric heat transfer from nanoparticles in lipid bilayers

- We study heat transfer from nanoparticles to lipid bilayer systems computationally.
- Nanoparticle position with respect to bilayer influences heat transfer efficiency.
- Hydrophilic nanoparticles heat the system more efficiently than hydrophobic particles.
- Heat conduction is asymmetric and has a discontinuity between the bilayer leaflets.
- Nanoparticle functionalization is a means to control heat transfer characteristics.

Here, we use molecular dynamics simulations to characterize the heat transfer properties of lipid bilayer - gold nanoparticle systems in which the nanoparticle acts as a heat source. The focus is on dipalmitoylphosphatidylcholine (DPPC) lipid bilayers and thiolated alcohol and alkyl functionalized nanoparticles as prototype hydrophilic and hydrophobic nanoparticles. We find hydrophilic nanoparticles which are partly in contact with the surrounding water environment are more efficient in transferring heat to the system than hydrophobic ones which reside surrounded by the membrane. This is because of the hydrogen bonding capability of the hydroxy pentanethiol and the more efficient heat conductivity through water than the lipid bilayer. Additionally, we find the heat conductance is strongly asymmetric and has a discontinuity between the bilayer leaflets. In total, the findings provide understanding on heat transport from localized heat sources in lipid bilayers and could bear significance, e.g., in engineering and controlling photoactivated triggering of liposomal systems.

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