title: Optical detection of lithocholic acid with liquid crystal emulsions.
abstract: The concentration level of bile acids is a clinical biomarker for the diagnosis of intestinal diseases because individuals suffering from intestinal diseases have a sharply increased concentration of bile acids at micromolar levels. Here, we report the detection of lithocholic acid (LCA) in aqueous solution by using surfactant-stabilized 4-n-pentyl-4'-cyanobiphenyl (5CB) liquid crystal droplets as an optical probe. We find that the surfactant adsorbed at the 5CB/water interface can be replaced by LCA, triggering a radial-to-bipolar configuration transition of the 5CB in the droplets. By simply observing the LCA-triggered transition with a polarizing optical microscope, micromolar levels of LCA in aqueous solution can be detected. The detection limit and selectivity of surfactant-stabilized 5CB droplets for LCA depend on the chain length and headgroup of the surfactants used for stabilizing 5CB droplets.
authors.affiliation: Department of Materials Science and Engineering, University of Central Florida, Orlando, Florida 32826, United States.
authors.forename: Tanmay
authors.initials: T
authors.lastname: Bera
authors.forename: Jiyu
authors.initials: J
authors.lastname: Fang
mesh_terms: D004355:Drug Stability; D004655:Emulsions / Q000737:chemistry*; D057230:Limit of Detection; D050866:Liquid Crystals / Q000737:chemistry*; D008095:Lithocholic Acid / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D008859:Microscopy, Polarization; D008954:Models, Biological; D015394:Molecular Structure; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D004655:Emulsions; D013501:Surface-Active Agents; D008095:Lithocholic Acid