TY - JOUR
T1 - Relationship between the mobility of phosphocholine headgroups of liposomes and the hydrophobicity at the membrane interface
T2 - A characterization with spectrophotometric measurements
AU - Shimanouchi, Toshinori
AU - Sasaki, Masashi
AU - Hiroiwa, Azusa
AU - Yoshimoto, Noriko
AU - Miyagawa, Kazuya
AU - Umakoshi, Hiroshi
AU - Kuboi, Ryoichi
N1 - Funding Information:
The authors thank the group of Engineering Science of Liposome and International Seminar between Japan Society for the Promotion of Science (JSPS)-Swiss National Scientific Foundation (SNSF). The authors would also like to thank the group of Membrane Stress Biotechnology. This work was partly supported by Grants-in-Aid for Scientific Research (nos. 21246121 , 23656525 ) from the Ministry of Education, Culture, Sports, Science and Technology of Japan . This work was also partly supported by the Core University Program between JSPS and the Vietnamese Academy of Science and Technology (VAST) . The authors thank Dr. Suguru Inoue (Horiba Co. Ltd., Kyoto, Japan) for a lifetime of TMA-DPH. It was partly supported by the Global COE program “Bio-Environmental Chemistry” of JSPS. The authors also thank the Gas Hydrate Analyzing System of Osaka University. It was partly funded by a Cabinet Office, Government of Japan through its “Funding Program for Next Generation World-Leading Researchers” (no. GR066 ).
PY - 2011/11/1
Y1 - 2011/11/1
N2 - In this study, we investigated the dynamics of a membrane interface of liposomes prepared by eight zwitterionic phosphatidylcholines in terms of their headgroup mobility, with spectroscopic methods such as dielectric dispersion analysis (DDA), fluorescence spectroscopy. The DDA measurement is based on the response of the permanent dipole moment to a driving electric field and could give the information on the axial rotational Brownian motion of a headgroup with the permanent dipole moment. This motion depended on kinds of phospholipids, the diameter of the liposomes, and the temperature. The activation energy required to overcome the intermolecular force between headgroups of phospholipids depended on the strength of the interaction between headgroups such as hydrogen bonds and/or dipole-dipole interaction. Hydration at the phosphorous group of phospholipid and the molecular order of lipid membrane impaired the interaction between headgroups. Furthermore, the hydrophobicity of membrane surface increased parallel to the increase in headgroup mobility. It is, therefore, concluded that hydration of headgroup promoted its mobility to make the membrane surface hydrophobic. The lipid membrane in liquid crystalline phase or the lipid membrane with the larger curvature was more hydrophobic.
AB - In this study, we investigated the dynamics of a membrane interface of liposomes prepared by eight zwitterionic phosphatidylcholines in terms of their headgroup mobility, with spectroscopic methods such as dielectric dispersion analysis (DDA), fluorescence spectroscopy. The DDA measurement is based on the response of the permanent dipole moment to a driving electric field and could give the information on the axial rotational Brownian motion of a headgroup with the permanent dipole moment. This motion depended on kinds of phospholipids, the diameter of the liposomes, and the temperature. The activation energy required to overcome the intermolecular force between headgroups of phospholipids depended on the strength of the interaction between headgroups such as hydrogen bonds and/or dipole-dipole interaction. Hydration at the phosphorous group of phospholipid and the molecular order of lipid membrane impaired the interaction between headgroups. Furthermore, the hydrophobicity of membrane surface increased parallel to the increase in headgroup mobility. It is, therefore, concluded that hydration of headgroup promoted its mobility to make the membrane surface hydrophobic. The lipid membrane in liquid crystalline phase or the lipid membrane with the larger curvature was more hydrophobic.
KW - Dielectric dispersion
KW - Dynamics
KW - Headgroup
KW - Hydrogen bonding
KW - Hydrophobicity
KW - Liposome
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U2 - 10.1016/j.colsurfb.2011.06.036
DO - 10.1016/j.colsurfb.2011.06.036
M3 - Article
C2 - 21831614
AN - SCOPUS:80052097791
VL - 88
SP - 221
EP - 230
JO - Colloids and Surfaces B: Biointerfaces
JF - Colloids and Surfaces B: Biointerfaces
SN - 0927-7765
IS - 1
ER -