Hydration water dynamics at biocompatible polymers
The feature to prevent blood clotting is known as "biocompatibility", and essentially important for a coating materials of medical devices. The origin of the biocompatibility is considered to be related with the feature of hydration water, however, the details have not been understood. We have done Quasi-Elastic Neutron Scattering (QENS) experiments to investigate the dynamical properties of hydration water near polymer chains of PEO (polyethylene oxide), and confirmed an existence of a significant amount of slow mode water.
T. Tominaga, M. Hishida, D. Murakami, Y. Fujii, M. Tanaka, and H. Seto
"Experimental Evidence of Slow Mode Water in the Vicinity of Poly(ethylene oxide) at Physiological Temperature"
Journal of Physical Chemistry B, 126, 1758-1767 (2022).
Y. Fujii, T. Tominaga, D. Murakami, M. Tanaka and H. Seto
"Local Dynamics of the Hydration Water and Poly(Methyl Methacrylate) Chains in PMMA Networks"
Frontiers in Chemistry, 9, 728738 (2021).
Shear-induced ordering of colloidal solution of hydroxyapatite
Stimuli-responsible hydroxyapatite-based colloidal liquid crystalline nanorods were examined using in situ small-angle neutron scattering (SANS) and rheological measurements under shear. The experimental results unraveled the effects of the shear force to form the hierarchial morphologies of nano-rods and their transitions.
S. Kajiyama, H. Iwase, M. Nakayama, R. Ichikawa, D. Yamaguchi, H. Seto and T. Kato
"Shear-induced liquid-crystalline phase transition behaviour of colloidal solutions of hydroxyapatite nanorod composites"
Nanoscale, 12, 11468-11479 (2020).
The dynamical behavior of hydration water near lipid membranes
Lipid molecules are main components of biological membranes and their physical properties intensively. QENS experiments verified the existence of three types of hydration water as free water, loosely bound water, and tightly bound water.
T. Yamada, N. Takahashi, T. Tominaga, S. Takata, and H. Seto
"Dynamical behavior of hydration water molecules between phospholipid membranes"
The Journal of Physical Chemistry Part B: Biophysical Chemistry, Biomaterials, Liquids, and Soft Matter, 121, 8322-8329 (2017).
H. Seto and T. Yamada
"Quasielastic neutron scattering study of the effects of metal cations on the hydration water between phospholipid bilayers"
Applied Physics Letters, 116, 133701 (2020)
M. K. Rahman, T. Yamada, N. L Yamada, M. Hishida, Y. Higuchi, and H. Seto
"Quasi-elastic neutron scattering reveals the relationship between the dynamical behavior of phospholipid headgroups and hydration water"
Structural Dynamics, 10, 044701 (2023).
The origin of the onion formation of surfactant bilayers under shear
The aqueous solution of non-ionic surfactant is known to form bilayers and the onion morphology is induced by applying shear. We investiged this transition by SANS and Neutron Spin Echo (NSE) spectroscopy, and verified the role of the inter-membrane interactions.
Y. Kawabata, R. Bradbury, S. Kugizaki, K. Weigandt, Y. B.
Melnichenko, K. Sadakane, N. L. Yamada, H. Endo, M. Nagao, and H.
"Effect of interlamellar interactions on shear induced multilamellar vesicle formation"
The Journal of Chemical Physics, 147, 035905 (2017).
Ordered structure induced by coupling of the solvation effect and cencentration fluctuation in mixtures of water, organic solvent and antagonistic salt
K. Sadakane, H. Seto, and M. Nagao, "Long-range periodic structure induced by coupling of the solvation effect and concentration fluctuation in water and 3-methylpyridine with salts",
Chemical Physics Letters, 426, 61-65 (2006).
K. Sadakane, H. Seto, H. Endo, and M. Kojima, "Mesoscopic structure in near-critical mixtures of D2O and 3-Methylpyridine with salts",
Journal of Applied Crystallography 40, s527-s531 (2007).
K. Sadakane, H. Seto, H. Endo, and M. Shibayama, "A Periodic Structure in a Mixture of D2O/3-Methylpyridine/NaBPh4 induced by Solvation Effect",
Journal of Physical Society of Japan 76, 113602 (2007).
K. Sadakane, A. Onuki, K. Nishida, S. Koizumi, and H. Seto, "Multilamellar Structures Induced by Hydrophilic and Hydrophobic Ions Added to a Binary Mixture of D2O and 3-Methylpyridine",
Physical Review Letters, 103, 167803 (2009).
K. Sadakane, N. Iguchi, M. Nagao, H. Endo, Y. B. Melnichenko, and H. Seto"2D-Ising-like critical behavior in mixtures of water and 3-methylpyridine including antagonistic salt or ionic surfactant" Soft Matter, 7, 1334 (2011).
K. Sadakane, Y. Horikawa, M. Nagao, and H. Seto
"The Effect of Tetraphenylphosphonium Chloride on Phase Behavior and Nanoscale Structures in a Mixture of D2O and 3-Methylpyridine"
Chemistry Letters, 41, 1075-1077 (2012).
K. Sadakane, H. Endo, K. Nishida, and H. Seto
"Lamellar/disorder phase transition in a mixture of water / 2,6-lutidine / antagonistic salt"
Journal of Solution Chemistry, 43, 1722 (2014).
K. Sadakane and H. Seto
"Membrane Formation in Liquids by Adding an Antagonistic Salt"
Fronteers in Physics, 6, Article 26 (2018).
Spontaneous deformation of an oil droplet on water surface
Y. Sumino, H. Kitahata, H. Seto, and K. Yoshikawa, "Blebbing dynamics in a oil-water-surfactant system through the generation and the destruction of a gel-like structure",
Physical Review E 76, 055202(R) (2007).
Y. Sumino, H. Kitahata, H. Seto, S. Nakata, and K. Yoshikawa, "Spontaneous Deformation of an Oil Droplet Induced by the Cooperative Transport of Cationic and Anionic Surfactants through the Interface",
Journal of Physical Chemistry B, 113 (48), 15709-15714 (2009).
Y. Sumino, H. Kitahata, H. Seto, and K. Yoshikawa, "Dynamical blebbing at a droplet interface driven by instability in elastic stress: a novel self-motile system",
Soft Matter, 7, 3204-3212 (2011).
Y. Sumino, H. Kitahata, Y.
Shinohara, N. L. Yamada, and H. Seto
“Formation of a multi-scale aggregate srtucture through spontaneous blebbing of an interface”
Langmuir 28, 3378-3384 (2012).
Y. Sumino, N. L. Yamada, M. Nagao, T. Honda, H. Kitahata, Yuri B.
Melnichenko, and H. Seto
"Mechanism of Spontaneous Blebbing Motion of an Oil-Water Interface: Elastic Stress Generated by a Lamellar-Lamellar Transition"
Langmuir, 32, 2891-2899 (2016).
Structure and dynamics of lipid bilayers and the vesicle formation process
N. L. Yamada, H. Seto, T. Takeda, M. Nagao, Y. Kawabata and K. Inoue, "SAXS, SANS and NSE studies on the "unbound state" in the DPPC/water/CaCl2 system", Journal of Physical Society of Japan, 74, 2853 - 2859 (2005).
M. Hishida, H. Seto, and Y. Yoshikawa, "Smooth / rough layering in liquid-crystalline / gel state of dry phospholipid film, in relation to its ability to generate giant vesicles", Chemical Physics Letters, 411, 267 - 272 (2005).
H. Seto, M. Hishida, H. Nobutou, N. L. Yamada, M. Nagao, and T. Takeda, "Strucutural Changes of Dipalmitoyl Phosphatidylcholine Aqueous Solution Induced by Temperature, Pressure, and Adding Ethanol", Journal of Physical Society of Japan, 76, 054602 (2007).
N. L. Yamada, M. Hishida, H. Seto, K. Tsumoto, and T. Yoshimura, "Unbinding of lipid bilayers induced by osmotic pressure in relation to unilamellar vesicle formation", Europhysics Letters, 80, 48002 (2007).
M. Hishida, H. Seto, N. L. Yamada, and K. Yoshikawa, "Hydration process of multi-stacked phospholipid bilayers to form giant vesicles", Chemical Physics Letters 455, 297 - 302 (2008).
H. Seto, N. L. Yamada, M. Nagao, M. Hishida, and T. Takeda, "Bending modulus of lipid bilayers in liquid-crystalline phase including anomalous swelling regime estimated by NSE experiments", The European Physical Journal E 26, 217-223 (2008).
M. Hishida, N. L. Yamada, K. Yoshikawa, and H. Seto, "Morphological development of multilamellar phospholipid film depending on drying kinetics", Physical Review E, 051407 (2009).
M. Hishida and H. Seto, "Lamellar-lamellar phase separation of phospholipid bilayers", Journal of Physics Conference Series, 272, 012008 (2011).
Relative form factor
M. Nagao, H. Seto, and N. L. Yamada, "Interaction between droplets in a ternary microemulsion evaluated by the relative form factor method", Physical Review E, 75, 061401 (2007).
M. Nagao and H. Seto, "Concentration dependence of shape and structure fluctuations of droplet microemulsions investigated by neutron spin echo spectroscopy", Physical Review E, 78, 011507 (2008).
Dynamics of micelles and microemulsion systems by Neutron Spin Echo spectroscopy
H. Seto, T. Kato, M. Monkenbusch, T. Takeda, Y. Kawabata, M. Nagao, D. Okuhara, M. Imai, and S. Komura, "Collective motions of a network of wormlike micelles.", The Journal of Physics and Chemistry of Solids, 60, 1371-1373 (1999).
S. Komura, T. Takeda, Y. Kawabata, S. K. Ghosh, H. Seto, and M. Nagao, "Dynamical fluctuation of the mesoscopic structure in ternary C12E5 / water / n-octane amphiphilic system", Physical Review E, 63, 041402 (2001).
S. Komura, T. Takeda, Y. Kawabata, S. K. Ghosh, H. Seto, and M. Nagao, "Hydrodynamic interactions in the structural fluctuation of a ternary amphiphilic system C12E5 / water / n-octane", The European Physics Journal E, 5, 329 (2001).
N. L. Yamada, T. Takeda, K. Kato, M. Nagao, and H. Seto, "Effect of confinement on membrane undulation in a swollen lamellar phase", Journal of Physical Society of Japan, 74, 875 - 877 (2005).
Pressure-induced phase transition in microemulsion systems
M. Nagao, and H. Seto, "A small angle neutron scattering study of a pressure induced phase transition in a ternary microemulsion composed of AOT, D2O, and n-decane.", Physical Review E, 59, No. 3, 3169 - 3176 (1999).
H. Seto, D. Okuhara, Y. Kawabata, T. Takeda, M. Nagao, J. Suzuki, H. Kamikubo, and Y. Amemiya, "Pressure and temperature effects on the phase transition from a dense droplet to a lamellar structure in a ternary microemulsion.", The Journal of Chemical Physics, 112, 10608-10614 (2000).
Y. Kawabata, M. Nagao, H. Seto, S. Komura, T. Takeda, D. Schwahn, N. L. Yamada, and H. Nobutou, "Temperature and pressure effects on the bending modulus of monolayers in a ternary microemulsion", Physical Review Letters, 92, 056103 (2004).
M. Nagao, H. Seto, D. Ihara, M. Shibayama, and T. Takeda, "Pressure-induced hexagonal phase in a ternary microemulsion system composed of a non-ionic surfactant, water, and oil", The Journal of Chemical Physics, 123, 054705 (2005)
Y. Kawabata, H. Seto, M. Nagao, and T. Takeda, "Pressure Effects on Bending Elasticities of Surfactant Monolayers in a Ternary Microemulsion Composed of AOT / D2O / decane", The Journal of Chemical Physics, 127, 044705 (2007).
Phase separation in ternary microemulsions and associated critical phenomena
H. Seto, D. Schwahn, K. Mortensen, and S. Komura, "A Small Angle Neutron Scattering Study of Density Fluctuations at Near-critical Region and a van der Waals Model in a 3-component Microemulsion." The Journal of Chemical Physics, 99, 5512 - 5519 (1993).
H. Seto, D. Schwahn, M. Nagao, E. Yokoi, S. Komura, M. Imai, and K. Mortensen, "Crossover from Meanfield to 3D-Ising Critical Behavior in a 3-Component Microemulsion System." Physical Review E 54, 629 - 633 (1996).
Precursor phenomena at martensitic transformaion in Fe-Pd alloy
H. Seto, Y. Noda and, Y. Yamada, "Precursor Phenomena at Martensitic Phase Transition in Fe-Pd Alloy . I. Two-Tetragonal-Mixed Phase and Crest-Riding-Periodon." Journal of the Physical Society of Japan, 59, 965 - 977 (1990).
H. Seto, Y. Noda, and Y. Yamada, "Precursor Phenomena at Martensitic Phase Transition in Fe-Pd Alloy. II. Diffuse Scattering and Embryonic Fluctuations." Journal of the Physical Society of Japan, 59, 978 - 986 (1990).