Fusion
of Ligand-Coated Nanoparticles with Lipid Bilayers:
Effect of Ligand Flexibility
- Publication date
- Publisher
Abstract
Amphiphilic,
monolayer-protected gold nanoparticles (AuNPs) have
recently been shown to insert into and fuse with lipid bilayers, driven
by the hydrophobic effect. The inserted transmembrane state is stabilized
by the “snorkeling” of charged ligand end groups out
of the bilayer interior. This snorkeling process is facilitated by
the backbone flexibility of the alkanethiol ligands that comprise
the monolayer. In this work, we show that fusion is favorable even
in the absence of backbone flexibility by modeling the ligands as
rigid rods. For rigid ligands, snorkeling is still accommodated by
rotations of the ligand with respect to the grafting point, but the
process incurs a more significant free energy penalty than if the
backbone were fully flexible. We show that the rigid rod model predicts
similar trends in the free energy change for insertion as the previous
flexible model when the size of the AuNPs is varied. However, the
rigidity of the ligand backbone reduces the overall magnitude of the
free energy change compared to that of the flexible model. These results
thus generalize previous findings to systems with hindered backbone
flexibility due to either structural constraints or low temperature