Amphiphilic nanoparticles can modify lipid membrane permeability

Lipid bilayers are the structural foundation of biological membranes and contain a characteristic hydrophobic interior that prevents passive permeation of water and other polar molecules. Proteins embedded in these membranes controllably modify these barrier properties by allowing selecting transport in response to environmental stimuli. Previous work from our group has demonstrated that a certain class of nanoparticles can assume a transmembrane configuration similar to these protein channels, and that charged ligands grafted to these nanoparticles can cross the hydrophobic interior of the membrane at an anomalous rate. In this work, we use molecular dynamics simulations to demonstrate that this ligand flipping behavior is associated with transient water transport across the membrane and can be exploited for altering the permeability of lipid membranes to water and charged solutes. Through a combination of free energy analysis and unbiased simulations, we reveal that this gating ability is sensitive to membrane tension, allowing these nanoparticles to function as synthetic mimics of mechanosensitive membrane channels, and have potential applications ranging from single-cell therapeutics to novel methods of water desalination.