title: Synthetic Mimics of Bacterial Lipid A Trigger Optical Transitions in Liquid Crystal Microdroplets at Ultralow Picogram-per-Milliliter Concentrations.
abstract: We report synthetic six-tailed mimics of the bacterial glycolipid Lipid A that trigger changes in the internal ordering of water-dispersed liquid crystal (LC) microdroplets at ultralow (picogram-per-milliliter) concentrations. These molecules represent the first class of synthetic amphiphiles to mimic the ability of Lipid A and bacterial endotoxins to trigger optical responses in LC droplets at these ultralow concentrations. This behavior stands in contrast to all previously reported synthetic surfactants and lipids, which require near-complete monolayer coverage at the LC droplet surface to trigger ordering transitions. Surface-pressure measurements and SAXS experiments reveal these six-tailed synthetic amphiphiles to mimic key aspects of the self-assembly of Lipid A at aqueous interfaces and in solution. These and other results suggest that these amphiphiles trigger orientational transitions at ultralow concentrations through a unique mechanism that is similar to that of Lipid A and involves formation of inverted self-associated nanostructures at topological defects in the LC droplets.
authors.affiliation: Department of Chemistry, and ‡Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Matthew C D
authors.initials: MC
authors.lastname: Carter
authors.affiliation: Department of Chemistry, and ‡Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Miller
authors.affiliation: Department of Chemistry, and ‡Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: James
authors.initials: J
authors.lastname: Jennings
authors.affiliation: Department of Chemistry, and ‡Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Chemistry, and ‡Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Mahesh K
authors.initials: MK
authors.lastname: Mahanthappa
authors.affiliation: Department of Chemistry, and ‡Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Abbott
authors.affiliation: Department of Chemistry, and ‡Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: David M
authors.initials: DM
authors.lastname: Lynn
mesh_terms: D008050:Lipid A / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D053838:Scattering, Small Angle; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D008050:Lipid A