On the interactions of diols and DMPC monolayers

The interactions of lipid molecules with various solvent molecules is of utmost importance in the formulation of various drug delivery and personal care formulations. In this manuscript, a series of all-atom molecular dynamics simulations were used to investigate how the structural and interfacial properties of a DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) monolayer change when interacting with a range of diols that have varying carbon chain lengths and patterns of hydroxylation. In comparison to water, we find that all of the diols studied result in a more disordered and thinner monolayer. Additionally, we find that the shorter diols with the hydroxyl groups on neighbouring carbons (1,2-ethanediol and 1,2-propanediol) are able to penetrate deeper into the head group region of the lipid monolayers and as a result significantly disorder and thin the monolayers. Like water, we find that the diols also form hydrogen-bonded networks that connect the DMPC head groups in neighbouring molecules. Interestingly, we find that the number of butanediol molecules that form these solvent-mediated interactions between the DMPC head groups is directly affected by the distribution of the hydroxyl groups within the diol molecules. The results presented here provide a mechanistic description of how the chemistry of diol solvent molecules will affect the structural and interfacial properties of lipid structures in solution.