Open AccessSynthetic Mimics of Bacterial Lipid A Trigger Optical Transitions in Liquid Crystal Microdroplets at Ultralow Picogram-per-Milliliter Concentrations
Author(s) -
Matthew C. D. Carter,
Daniel S. Miller,
James Jennings,
Xiaoguang Wang,
Mahesh Mahanthappa,
Nicholas L. Abbott,
David M. Lynn
Publication year - 2015
Publication title -
langmuir
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.042
H-Index - 333
eISSN - 1520-5827
pISSN - 0743-7463
DOI - 10.1021/acs.langmuir.5b03557
Subject(s) - liquid crystal , monolayer , chemistry , amphiphile , small angle x ray scattering , lipid a , nanostructure , aqueous solution , molecule , self assembly , lipid ii , nanotechnology , chemical engineering , chromatography , biophysics , chemical physics , organic chemistry , materials science , bacteria , scattering , optics , biochemistry , biosynthesis , biology , copolymer , genetics , polymer , enzyme , physics , optoelectronics , engineering
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.