Faculty Profiles - SHIMANOUCHI Toshinori

Papers - SHIMANOUCHI Toshinori

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Development of metal affinity-immobilized liposome chromatography and its basic characteristics

Hideto Nagami, Hiroshi Umakoshi, Takenori Kitaura, Gary Lee Thompson, Toshinori Shimanouchi, Ryoichi Kuboi

BIOCHEMICAL ENGINEERING JOURNAL 84 66 - 73 2014.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Metal affinity-immobilized liposome chromatography (MA-ILC) was newly developed as a chromatographic technique to separate and analyze peptides. The MA-ILC matrix gel was first prepared by immobilizing liposomes modified with functional ligands. The functional ligand used to adsorb metal ions was N-hexadecyl iminodiacetic acid (HIDA), which is obtained by attaching a long alkyl chain to an iminodiacetic acid (IDA). Cu(II) ion was first adsorbed on the gel matrix through its complex formation with the HIDA on the surface of the immobilized liposome. Synthetic peptides of various types ranging in size from 5 to 40 residues were then used, and their retention properties on the MA-ILC were evaluated. The retention property of peptides on the MA-ILC by using a usual imidazole elution was compared with the retention property in the case of the immobilized metal affinity chromatography (IMAC) and an immobilized liposome chromatography (ILC). It was found that the retention property of peptides on the MA-ILC has the features of both the IMAC and the ILC; the retention ability of peptides depends on both the number of histidine residues in peptides and the liposome membrane affinity of the peptides. Histidine and tryptophan residues among amino acid residues in peptides indicated a high contribution coefficient for the peptide retention on the MA-ILC, probably due to their metal ion and membrane interaction properties, respectively. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.bej.2013.12.017

Water/Methyl isobutyl ketone (MIBK) Biphasic System in Slug Flow under High Temperature and Pressure Conditions

Toshinori Shimanouchi, Tatsuya Tanifuji, Satoko Fujioka, Koichi Terasaka, Yukitaka Kimurai

SOLVENT EXTRACTION RESEARCH AND DEVELOPMENT-JAPAN 21 201 - 209 2014

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN ASSOC SOLVENT EXTRACTION

The clarification of the partition property of substrates in a water / organic biphasic system is useful in the development of a reaction / separation process for value-added materials, especially under high temperature and pressure conditions. In this study, the water / methyl isobuthyl ketone (MIBK) biphasic system was investigated under various temperatures (25 190 degrees C) at 10 MPa. The partitioning behavior of substrates such as furfural derivatives, amino acids, and saccharides, depended on the temperature and the flow rate ratio of MIBK to the water phase. The scale of hydrophobicity (HF) of the water / MIBK biphasic system to determine the partitioning behavior of substrates was estimated based on the partitioning behavior of amino acids. The HF value for the water / MIBK phase flow system of was greater than that for the batch system and comparable to that for conventional aqueous two-phase systems such as polyethylene glycol / dextran and liposome membrane systems. It was probably because an increase of the surface-to-volume ratio and the vortex field in the slug flow contributed to the mass transfer of substrates and their distribution.

DOI： 10.15261/serdj.21.201

Subcritical Water-Assisted Emulsification of Decane/Water: Influence of Surfactants

Toshinori Shimanouchi, Takashi Tange, Yukitaka Kimura

SOLVENT EXTRACTION RESEARCH AND DEVELOPMENT-JAPAN 21 103 - 110 2014

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN ASSOC SOLVENT EXTRACTION

A finely monodispersed oil-in-water (O/W) emulsion was obtained under high temperature and pressure conditions (240 degrees C and 10 MPa). A coarse emulsion stabilized by Tween 20 was prepared in advance from the decane / water system to be treated under the subcritical conditions. The treated coarse emulsion was thereafter mixed with the aqueous solution including surfactants to improve the monodispersity of the oil droplets. The subcritical condition could supply sufficient energy to produce finely dispersed oil droplets (similar to 233 nm in diameter).

DOI： 10.15261/serdj.21.103

Comparison of the Interfacial Properties of Span 80 Vesicle, W/O Emulsions and Liposomes

Keita Hayash, Hiroshi Umakosile, Toshinori Shimanouchi

SOLVENT EXTRACTION RESEARCH AND DEVELOPMENT-JAPAN 21 191 - 199 2014

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN ASSOC SOLVENT EXTRACTION

Vesicles composed of sorbitan monooleate (Span 80) were prepared by a two-step emulsification method. The water-in-oil (W/O) emulsions generated in the first step of emulsification exhibited a quite dynamic and large hydrophobic difference between water and hexane. A subsequent emulsification yielded the vesicles with a fluid and flexible interface, as compared with that of liposomes. It was furthermore demonstrated that the two-step emulsification method has the advantage of the introduction of a PEG layer into the outer surface of the vesicles, while retaining the membrane properties of the vesicles.

DOI： 10.15261/serdj.21.191

Subcritical Water-Assisted Emulsification of Oil/Water: The Effect of the Solubility of the Organic Solvent and Surfactants

Toshinori Shimanouchi, Takashi Tange, Yukitaka Kimura

SOLVENT EXTRACTION RESEARCH AND DEVELOPMENT-JAPAN 21 223 - 230 2014

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN ASSOC SOLVENT EXTRACTION

The formation of finely monodispersed oil-in-water (O/W) emulsions under high temperature and pressure conditions (240 degrees C and 10 MPa) depended on the solubility of the oil in water. Fatty acids with large solubilities in water favored the formation of oil droplets in emulsions of less than 100 nm in diameter. The water dissolved in the oil droplets participated throughout the cooling process, followed by the break-down of the oil droplets. In contrast, organic solvents with lower solubilities in water formed oil droplets in emulsions that had at most a diameter of 300 nm.

DOI： 10.15261/serdj.21.223

Membrane interaction between Span 80 vesicle and phospholipid vesicle (liposome): Span 80 vesicle can perturb and hemifuse with liposomal membrane. International journal

Keita Hayashi, Tsuyoshi Tatsui, Toshinori Shimanouchi, Hiroshi Umakoshi

Colloids and surfaces. B, Biointerfaces 106 258 - 64 2013.6

Language：English Publishing type：Research paper (scientific journal)

We have focused on the interaction between the Span 80 vesicle and phospholipid vesicle (liposome). The Span 80 vesicle was mixed with a phospholipid vesicle (liposome), used as a simplified model of plasma membrane. From calcein leakage experiments, it was revealed that the interaction between the Span 80 vesicles and the liposomes could perturb the liposome membrane. In the experiments based on fluorescence resonance energy transfer, the lipid mixing between Span 80 vesicle and liposome was observed. The above phenomena were also supported by the fluorescence spectroscopic analysis using laurdan, resulting in the variation in the membrane properties of liposome after its mixing with Span 80 vesicle. These results suggest that the Span 80 vesicles can easily interact and hemifuse with the liposome membrane, which depend on the membrane properties of the Span 80 vesicle, "flexible" and "molecular structure" of the components.

DOI： 10.1016/j.colsurfb.2012.12.022

Membrane fusion mediated by phospholipase C under endosomal pH conditions

Toshinori Shimanouchi, Hidenori Kawasaki, Makoto Fuse, Hiroshi Umakoshi, Ryoichi Kuboi

Colloids and Surfaces B: Biointerfaces 103 75 - 83 2013.3

Language：English Publishing type：Research paper (scientific journal)

Phospholipase C (PLC) is considered to be one of key enzymes for the design of drug delivery system using the endocytosis route, because PLC can catalyze the membrane fusion between cell membranes and phospholipid vehicles (liposomes). Membrane fusion by PLC was then studied under various pHs to model the endosomal environment. The used liposomes were composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and cholesterol (Ch). The membrane fusion was dominated by the enzymatic reaction at pH 6-7.5. In contrast, the membrane perturbation effect due to the conformational change of PLC could induce the membrane fusion at around pH 4. The maximal value of membrane fusion was observed at around pH 5 for three liposomes in the order of DOPC &lt
DOPC/DPPC (1:1) &lt
DOPC/DPPC/Ch (1:1:1). From the experiments with the hydrophobic fluorescence probe and the circular dichroic method, it was revealed that PLC took a molten-globule state, with a large fluctuation and an enzymatic activity, at around pH 4-5. The DAG-rich domain enzymatically produced by PLC played role for the field for the membrane perturbation enough to lead to the membrane fusion. The present finding would be helpful to understand the behavior of membrane fusion under the late endosomal pH condition in cell system. © 2012 Elsevier B.V.

DOI： 10.1016/j.colsurfb.2012.10.011

Growth behavior of giant vesicles using the electroformation method: Effect of proteins on swelling and deformation

Toshinori Shimanouchi, Hiroshi Umakoshi, Ryoichi Kuboi

JOURNAL OF COLLOID AND INTERFACE SCIENCE 394 269 - 276 2013.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

The growth of giant vesicles (GVs) can be considered as a consecutive process of swelling/detachment/deformation, which is a response of lipid membranes on solid surfaces to the solvent and environmental factors such as temperature and ionic strength. The electroformation method allows to visualize the responses to such factors. The additive effect of the protein on the growth of GVs, composed of zwitterionic phospholipids, was herein investigated using the electroformation method. Proteins denatured by a pH-shift (to be in the Molten Globule state) perturbed the lipid membranes, resulting in the acceleration of GV growth. The GVs detached from the electrode showed deformation close to a stomatocyte. It was revealed that common factor for the response of lipid membranes was the variation of the apparent area elastic modulus associated with the interaction between proteins and lipid membranes. The present finding affords better understanding about the response of lipid membranes on solid surfaces under a variety of environment factors. (C) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcis.2012.11.046

Growth behavior of A beta protofibrils on liposome membranes and their membrane perturbation effect

Toshinori Shimanouchi, Keiichi Nishiyama, Azusa Hiroiwa, Huong Thi Vu, Nachi Kitaura, Hiroshi Umakoshi, Ryoichi Kuboi

BIOCHEMICAL ENGINEERING JOURNAL 71 81 - 88 2013.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

The protofibrils of amyloid fibrils have recently drawn an attention due to their cytotoxicity although the physicochemical properties of the protofibrils as an intermediate of fibrillation process have still remained unclear. We investigated the growth behavior of the protofibrils of amyloid beta protein with 40 amino acid residues in the presence of various liposornes and the membrane perturbation (calcein leakage). The growth behavior of protofibrils was apparently correlated with the protofibrils-induced calcein leakage. From the binding experiment using a hydrophobic fluorescence probe and the quartz crystal microbalance method combined with the planar lipid membrane, it is suggested that the apparent correlation between the growth behavior of protofibrils and their membrane perturbation resulted from the physicochemical properties of protofibrils such as hydrophobicity and the stability of hydrogen bonds. The protofibrils were found to show the highest hydrophobicity and the highest instability of hydrogen bonds of the proteins used in this study (monomer, protofibrils, matured fibrils, and other three typical proteins). It is anticipated that such properties of protofibrils were advantageous both for the binding of protofibrils with monomer (growth behavior) and for the binding of lipid bilayer membranes (membrane perturbation). (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.bej.2012.11.006

Effect of liposome membranes on disaggregation of amyloid beta fibrils by dopamine

Huong Thi Vu, Toshinori Shimanouchi, Daisuke Ishikawa, Tadaharu Matsumoto, Hisashi Yagi, Yuji Goto, Hiroshi Umakoshi, Ryoichi Kuboi

BIOCHEMICAL ENGINEERING JOURNAL 71 118 - 126 2013.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

The inhibition of fibril formation of amyloid beta (A beta) and the disaggregation of A beta fibrils are the promising approaches for a medical treatment of Alzheimer's disease (AD) therapy. In this study, we investigated the effects of liposomes on dopamine-induced disaggregation of A beta fibrils by using the variety of liposomes. The used liposomes were normal liposomes, raft-forming liposomes, charged liposomes and oxidized liposomes. Those liposome could accelerate the disaggregation rate of fibrils. From the comparison of normal and charged liposomes, a certain contribution of dopamine via an electrostatic interaction to the disaggregation was confirmed. From raft-forming and oxidized liposomes, we revealed a significant contribution of bound water to liposomes, which could assist the formation of the quinine-form of dopamine by a removal of its proton. It is, therefore, concluded that the membrane surface of liposomes is considered to be an adequate environment for the dopamine-induced disaggregation of fibrils. (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.bej.2012.12.012

Simplified Model for Extraction of 5-Hydroxymethylfurfural from Fructose: Use of Water/Oil Biphasic System under High Temperature and Pressure Conditions

Toshinori Shimanouchi, Yoshitaka Kataoka, Masahiro Yasukawa, Tsutomu No, Yukitaka Kimura

SOLVENT EXTRACTION RESEARCH AND DEVELOPMENT-JAPAN 20 205 - 212 2013

Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN ASSOC SOLVENT EXTRACTION

5-Hydroxymethylfurfural (HMF) was obtained from the dehydration of fructose under high temperature and pressure conditions (180 degrees C and 10 MPa). To avoid the decomposition of HMF in the bulk aqueous phase, we dehydrated fructose in the water / metyl isobuthyl ketone (MIBK) biphasic system. The HMF could be successfully extracted into the organic MIBK phase without further decomposition of HMF. We present a simplified model taking into consideration of the slug flow with the wall film to maximize the HMF yield in the MIBK phase. It was likely that the slug flow contributed to an increase in the surface-to-volume ratio for the mass transfer of HMF.

DOI： 10.15261/serdj.20.205

Enhanced Cytotoxicity for Colon 26 Cells Using Doxorubicin-Loaded Sorbitan Monooleate (Span 80) Vesicles

Keita Hayashi, Tsuyoshi Tatsui, Toshinori Shimanouchi, Hiroshi Umakoshi

INTERNATIONAL JOURNAL OF BIOLOGICAL SCIENCES 9 ( 2 ) 142 - 148 2013

Language：English Publishing type：Research paper (scientific journal) Publisher：IVYSPRING INT PUBL

Span 80 (sorbitan monooleate) vesicles behaved differently from conventional phospholipid vesicles (liposomes) because the former had a more fluid interface. After doxorubicin hydrochloride (DOX) was encapsulated into the Span 80 vesicle (loading efficiency: 63 %), DOX-loaded Span 80 vesicles (DVs) were thereafter added to Colon 26 cells. It was suggested, from the flow cytometric analysis and confocal laser microscopic observation, that DVs directly deliver DOX into the cytoplasm of Colon 26 cells. DVs showed the different delivery manner from the DOX-loaded liposomes (DLs). It is considered that the difference of delivery manner between DVs and DLs resulted in the difference of cytotoxicity (IC50); i.e. IC50 values for DVs and DLs were 5 and > 30 mu M, respectively. The results obtained herein would give the fundamental findings which can contribute to the improvement of formulation of conventional liposome-based carrier and its cytotoxicity.

DOI： 10.7150/ijbs.5453

Secondary nucleation of A beta fibrils on liposome membrane

Toshinori Shimanouchi, Nachi Kitaura, Ryo Onishi, Hiroshi Umakoshi, Ryoichi Kuboi

AICHE JOURNAL 58 ( 12 ) 3625 - 3632 2012.12

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

The amyloid fibrils of amyloid beta protein (A beta) from Alzheimer's disease are likely to show the cytotoxicity, depending on their morphology. The relationship between the nucleation kinetics of the A beta fibrils and their morphology has been investigated. From the perspective of a crystallization technique assuming primary/secondary nucleation steps and an elongation step, the secondary nucleation rate B [# m-3 s-1], was experimentally and coarsely determined by using total internal reflection fluorescence microscopy combined with thioflavin T. In an aqueous solution, linear and rigid fibrils were formed with a relatively smaller B value ((2.83 +/- 0.55) x 105 # m-3 s-1), whereas spherulitic amyloid assemblies were formed in the presence of negatively charged liposome including oxidized lipids, with a larger B value ((7.65 +/- 0.47) x 105 # m-3 s-1). Those findings should lead to a better understanding of the mechanism for the formation of fibrils and senile plaques in Alzheimer's disease. (C) 2012 American Institute of Chemical Engineers AIChE J, 2012

DOI： 10.1002/aic.13772

Formation of spherulitic amyloid beta aggregate by anionic liposomes

Toshinori Shimanouchi, Naoya Shimauchi, Ryo Ohnishi, Nachi Kitaura, Hisashi Yagi, Yuji Goto, Hiroshi Umakoshi, Ryoichi Kuboi

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 426 ( 2 ) 165 - 171 2012.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Alzheimer's disease is the most common form of senile dementia. This neurodegenerative disorder is characterized by an amyloid deposition in senile plaques, composed primarily of fibrils of an aggregated peptide, amyloid beta (A beta). The modeling of a senile plaque formation on a model neuronal membrane under the physiological condition is an attractive issue. In this study, we used anionic liposomes to model the senile plaque formation by A beta. The growth behavior of amyloid All fibrils was directly observed, revealing that the induction of the spherulitic A beta aggregates could result from the growth of seeds in the presence of anionic liposomes. The seeds of A beta fibrils strongly interacted with negatively charged liposome and the subsequent association of the seeds were induced to form the seed cluster with many growth ends, which is advantageous for the formation of spherulitic A beta aggregates. Therefore, anionic liposomes mediated not only fibril growth but also the aggregation process. These results imply that anionic liposome membranes would affect the aggregate form of All fibrils. The modeling of senile plaque reported here is considered to have great potential for study on the amyloidosis. (c) 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2012.07.107

Effect of copper (II) ion against elongation behavior of amyloid ss fibrils on liposome membranes

T. Shimanouchi, R. Onishi, N. Kitaura, H. Umakoshi, R. Kuboi

CRYSTAL RESEARCH AND TECHNOLOGY 47 ( 1 ) 101 - 108 2012.1

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

The fibril growth behavior of amyloid beta protein (A beta) on cell membranes is relating to the progression of Alzheimer's disease. This growth behavior of A beta fibrils is sensitively affected by the metal ions, neurotransmitters, or bioreactive substrate. The inhibitory effect of those materials was quantitatively estimated from the viewpoints of crystal growth. In a bulk aqueous solution, copper (II) ion showed the strong inhibitory effect on the growth of A beta fibrils. Meanwhile, the addition of a closed-phospholipid bilayer membrane (liposome) could reduce the above inhibitory effect of copper (II) ion. (c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

DOI： 10.1002/crat.201100344

A New Intact Immobilization of Liposome as Sensing Bio Nano-Particle on Oxidized Metal Electrode Surface

Minoru Noda, Keisuke Takada, Mariko Nakai, Kaoru Yamashita, Toshinori Shimanouchi, Hiroshi Umakoshi

2012 IEEE SENSORS PROCEEDINGS 25 - 28 2012

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

We newly report that the intactness of liposome on the electrode surfaces of Pt and Au metals could be significantly improved on thermally oxidized metal surfaces, compared to those with non-oxidization or even with a SAM treatment. It is especially noted that the sub-gel phase of lipid membrane of the liposome on the oxidized Pt surface is much more suppressed than the case of non-oxidized, indicating that the fluidity of intact liposome greatly improves, as the sub-gel phase then crystalline phase will increase when the intact liposome loses its closed spherical shape. Finally, the retention time of the intact liposome on the oxidized surface becomes improved to about one day. These results indicate that the oxidation treatment made the metal surface hydrophilic enough to keep the stable and intact liposome. We think that the retention time up to one day is good enough for practical biosensor applications using intact liposome to improve device performance and its reliabilities.

DOI： 10.1109/ICSENS.2012.6411074

A New Biosensing by Dielectric Dispersion Analysis of Interaction between Lipid Membrane of Liposome and Target Biomolecules up to 20 GHz Range

Keisuke Takada, Kaoru Yamashita, Minoru Noda, Toshinori Shimanouchi, Hiroshi Umakoshi

2012 IEEE SENSORS PROCEEDINGS 935 - 938 2012

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper reports, firstly, that it was newly found by our specific Dielectric Dispersion Analysis (DDA) that plural type of bound water with different relaxation frequencies exist in a suspension of liposome of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Secondly, we observe that the interaction between the liposome and a specific target biomolecule depends on the type of target molecules (we used a protein of carbonic anhydrase from bovine (CAB) and/or cholesterol, respectively), leading to the change in dielectric relaxation at different relaxation frequency of bound water. It is finally concluded that the developed DDA method allows us to acquire the quantitative information with respect to bound water to liposomes, which gives novel physical insight on interaction between liposomes and target biomolecules (especially, protein).

DOI： 10.1109/ICSENS.2012.6411071

A planar-type leakage current and impedance microsensor for detection of interaction between electrolyte-entrapping liposome and protein

Y. Ohara, P. Lorchirachoonkul, K. Yamashita, M. Noda, O. A. Alberto, T. Shimanouchi

IMFEDK 2012 - 2012 International Meeting for Future of Electron Devices, Kansai 146 - 147 2012

Language：English Publishing type：Research paper (international conference proceedings)

We have developed a new leakage current microsensor by using simpler planar processes than Si-surface-bulk micromachining processes used in the previous microwell structure. This sensor fabrication and structure can easily make a target solution volume smaller than μL with excellent immobilization of the droplet and intact biomolecules as sensing elements, as a result, reduce effectively the background noise current in the microsensor and improve reproducibility of the results. The leakage current due to the biochemical interaction was successfully evaluated. Cole-Cole plots from the impedance analysis also show quantitative difference between with and without the interaction, depending on the charge-transfer impedance. © 2012 IEEE.

DOI： 10.1109/IMFEDK.2012.6218624

Copper-mediated growth of amyloid beta fibrils in the presence of oxidized and negatively charged liposomes

Toshinori Shimanouchi, Ryo Onishi, Nachi Kitaura, Hiroshi Umakoshi, Ryoichi Kuboi

JOURNAL OF BIOSCIENCE AND BIOENGINEERING 112 ( 6 ) 611 - 615 2011.12

Language：English Publishing type：Research paper (scientific journal) Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN

Amyloid beta protein (A beta) from Alzheimer's disease formed fibrillar aggregates and their morphology depended on oxidized and negatively charged liposomes. The morphology of fibrillar aggregates was affected by Cu2+, together with their growth kinetics. This is because Cu2+ inhibited the nucleation step in the formation of amyloid A beta fibrillar aggregates by forming A beta/Cu complex inactive to the growth of fibrillar aggregates. In addition, this is probably because Cu2+ affected the fibrillar aggregate formed on the surface of liposomes. These findings would give a better understanding of the formation mechanism of amyloid fibrils on biomembranes. (C) 2011, The Society for Biotechnology, Japan. All rights reserved.

DOI： 10.1016/j.jbiosc.2011.08.015

Relationship between the mobility of phosphocholine headgroups of liposomes and the hydrophobicity at the membrane interface: A characterization with spectrophotometric measurements

Toshinori Shimanouchi, Masashi Sasaki, Azusa Hiroiwa, Noriko Yoshimoto, Kazuya Miyagawa, Hiroshi Umakoshi, Ryoichi Kuboi

COLLOIDS AND SURFACES B-BIOINTERFACES 88 ( 1 ) 221 - 230 2011.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

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. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfb.2011.06.036

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