title: Domed Silica Microcylinders Coated with Oleophilic Polypeptides and Their Behavior in Lyotropic Cholesteric Liquid Crystals of the Same Polypeptide.
abstract: Liquid crystals can organize dispersed particles into useful and exotic structures. In the case of lyotropic cholesteric polypeptide liquid crystals, polypeptide-coated particles are appealing because the surface chemistry matches that of the polymeric mesogen, which permits a tighter focus on factors such as extended particle shape. The colloidal particles developed here consist of a magnetic and fluorescent cylindrically symmetric silica core with one rounded, almost hemispherical end. Functionalized with helical poly(γ-stearyl-l-glutamate) (PSLG), the particles were dispersed at different concentrations in cholesteric liquid crystals (ChLC) of the same polymer in tetrahydrofuran (THF). Defects introduced by the particles to the director field of the bulk PSLG/THF host led to a variety of phases. In fresh mixtures, the cholesteric mesophase of the PSLG matrix was distorted, as reflected in the absence of the characteristic fingerprint pattern. Over time, the fingerprint pattern returned, more quickly when the concentration of the PSLG-coated particles was low. At low particle concentration the particles were "guided" by the PSLG liquid crystal to organize into patterns similar to that of the re-formed bulk chiral nematic phase. When their concentration increased, the well-dispersed PSLG-coated particles seemed to map onto the distortions in the bulk host's local director field. The particles located near the glass vial-ChLC interfaces were stacked lengthwise into architectures with apparent two-dimensional hexagonal symmetry. The size of these "crystalline" structures increased with particle concentration. They displayed remarkable stability toward an external magnetic field; hydrophobic interactions between the PSLG polymers in the shell and those in the bulk LC matrix may be responsible. The results show that bio-inspired LCs can assemble suitable colloidal particles into soft crystalline structures.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Rosu
authors.forename: Shane
authors.initials: S
authors.lastname: Jacobeen
authors.affiliation: Molecular Vista, Inc., 6840 Via Del Oro, Suite 110, San Jose, California 95119, United States.
authors.forename: Katherine
authors.initials: K
authors.lastname: Park
authors.forename: Elsa
authors.initials: E
authors.lastname: Reichmanis
authors.forename: Peter
authors.initials: P
authors.lastname: Yunker
authors.forename: Paul S
authors.initials: PS
authors.lastname: Russo
mesh_terms: D050866:Liquid Crystals; D060526:Magnetic Fields; D010455:Peptides / Q000737:chemistry*; D011108:Polymers; D012822:Silicon Dioxide
chemical_list: D010455:Peptides; D011108:Polymers; D012822:Silicon Dioxide