Molecular modelling of surfactant monolayers under constraints derived from neutron reflectance measurements

Reverse Monte Carlo simulations have been carried out to provide molecular- level detail on the structures of three different lipid and surfactant mono layers of particular relevance in the design and development of drugs and d rug delivery systems. The simulations were performed using the SURFISS prog ram, with the orientations and conformations of the molecules in the monola yers optimised iteratively using constraints furnished from neutron reflect ance-derived volume fraction profile data. The three systems modelled invol ve the monolayers formed at the air/water interface by the synthetic surfac tants N,N-dimethyldodecylamine-N-oxide and 1,2-di-O-octadecyl-rac-glyceryl- 3-(omega -methoxydodecaoxyethylene) and the self-assembled layer of dimyris toylphosphatidylcholine adsorbed onto silicon hydrophobized by treatment wi th octadecyltrichlorosilane.