Supramolecular architecture of a multi-component biomimetic lipid barrier formulation.

HYPOTHESIS:Biomimetic liquid crystalline systems are widely used in skin care cosmetics and topical pharmaceutical preparations. Our ability to rationally design such formulations, however, is hampered by our incomplete understanding of their structure on the nanoscale. EXPERIMENTS:Using polarized light microscopy and small-angle and wide-angle X-ray scattering, the molecular architecture and properties of a barrier formulation prepared from distearoylphosphatidylcholine mixed with long chain fatty acid and alcohols, with and without antimicrobial pentanediols are directly probed. The nature and composition of the phases identified are determined through small-angle neutron scattering studies using chain-deuterated components, and the detailed structure and dynamics of the gel network lamellae are determined through molecular dynamics simulations. FINDINGS:The formulations show molecular ordering with long and short periodicity lamellar phases and there is little change in these structures caused by changes in temperature, drying, or the application of shear stress. The diol-free formulation is demonstrated to be self-preserving, and the added pentanediols are shown to distribute within the interlamellar regions where they limit availability of water for microbial growth. In culmination of these studies, we develop a more complete picture of these complex biomimetic preparations, and thereby enable their structure-based design.