title: Dielectric relaxation change of water upon phase transition of a lipid bilayer probed by terahertz time domain spectroscopy.
abstract: We investigate the influence of the 1, 2-ditetradecanoyl-sn-glycero-3-phosphocholine lipid bilayer phases on the water reorientation dynamics with terahertz time domain spectroscopy. The phase of the lipids was controlled by the temperature in the range of 14-35 °C. During the gel-to-fluid phase transition, the hydration water ratio drastically changed from 0.3 to 0.6. The absorption coefficient of the hydration water increased with the temperature in the gel phase and then decreased in the fluid phase. The dielectric relaxation time of the lipid solution decreased initially but then increased after the phase transition. This indicates that the hydration water reorientation dynamics are restricted by lipids and that this phenomenon is pronounced in a biologically relevant fluid phase.
authors.affiliation: Center for THz-Bio Application Systems, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, South Korea.
authors.forename: Da-Hye
authors.initials: DH
authors.lastname: Choi
authors.forename: Heyjin
authors.initials: H
authors.lastname: Son
authors.forename: Seonghoon
authors.initials: S
authors.lastname: Jung
authors.forename: Jaehun
authors.initials: J
authors.lastname: Park
authors.forename: Woong-Yang
authors.initials: WY
authors.lastname: Park
authors.forename: Oh Sang
authors.initials: OS
authors.lastname: Kwon
authors.forename: Gun-Sik
authors.initials: GS
authors.lastname: Park
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D017097:Electric Impedance; D008051:Lipid Bilayers / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D044367:Phase Transition; D013057:Spectrum Analysis; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D014867:Water; D004134:Dimyristoylphosphatidylcholine