title: Lanthanide phytanates: liquid-crystalline phase behavior, colloidal particle dispersions, and potential as medical imaging agents.
abstract: Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy. Several of the hydrated salts form a liquid-crystalline hexagonal columnar mesophase at room temperature, and samarium(III) phytanate forms this phase even in the absence of water. Select lanthanide phytanates were dispersed in water, and cryo-TEM images indicate that some structure has been retained in the dispersed phase. NMR relaxivity measurements were conducted on these systems. It has been shown that a particulate dispersion of gadolinium(III) phytanate displays proton relaxivity values comparable to those of a commercial contrast agent for magnetic resonance imaging and a colloidal dispersion of europium(III) phytanate exhibits the characteristics of a fluorescence imaging agent.
authors.affiliation: CSIRO Molecular and Health Technologies, Private Bag 10, Clayton South MDC, VIC 3169, Australia.
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Conn
authors.forename: Venkateswarlu
authors.initials: V
authors.lastname: Panchagnula
authors.forename: Asoka
authors.initials: A
authors.lastname: Weerawardena
authors.forename: Lynne J
authors.initials: LJ
authors.lastname: Waddington
authors.forename: Danielle F
authors.initials: DF
authors.lastname: Kennedy
authors.forename: Calum J
authors.initials: CJ
authors.lastname: Drummond
mesh_terms: D002151:Calorimetry; D003102:Colloids; D003287:Contrast Media / Q000138:chemical synthesis / Q000737:chemistry; D003952:Diagnostic Imaging / Q000379:methods*; D028581:Lanthanoid Series Elements / Q000138:chemical synthesis / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D046529:Microscopy, Electron, Transmission; D008859:Microscopy, Polarization; D008958:Models, Molecular; D008968:Molecular Conformation; D057054:Molecular Imaging / Q000379:methods*; D010831:Phytanic Acid / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D003102:Colloids; D003287:Contrast Media; D028581:Lanthanoid Series Elements; D014867:Water; D010831:Phytanic Acid