Details of a Researcher - Asakura, Kouichi

Papers - Asakura, Kouichi

Division display >> ／ All the affair displays 1 - 103 of about 103

Molecular insights into the motion of oil droplets in aqueous solutions of ester- and amide-containing cationic surfactants

Ueno K., Ishiwatari Y., Sasaki K., Kojima T., Takai A., Asakura K., Arai N., Banno T.

Journal of Molecular Liquids 426 2025.05

ISSN 01677322

The study of self-propelled motion in soft matter systems has garnered significant interest owing to its potential applications in microfluidics, soft robotics, and autonomous system design. Understanding the molecular mechanisms underlying motility is crucial for advancing these applications. This study investigates the self-propelled motion of lauronitrile oil droplets in aqueous surfactant solutions, focusing on the impact of different surfactant molecular structures on droplet dynamics. This study compares surfactants with ester and amide linkages, highlighting their critical role in modulating interfacial tension and driving Marangoni convection, a key factor behind droplet movement. Surfactants with ester linkages exhibit a high affinity for lauronitrile and rapidly adsorb at the oil–water interface, generating strong Marangoni flows and driving fast droplet motion. In contrast, amide-containing surfactants exhibit slower adsorption and weaker interactions with lauronitrile, leading to reduced or absent motion. These findings provide new insights into the molecular mechanisms underlying the self-propelled droplet behavior in non-equilibrium systems and contribute to a deeper understanding of self-organizing phenomena.

Access to Document (DOI)

A molecular strategy for creating functional vesicles with balancing structural stability and stimuli-responsiveness

Sasaki S., Ueno H., Arai N., Asakura K., Banno T.

Nanoscale 17 ( 11 ) 6863 - 6873 2025.02

ISSN 20403364

Vesicles, closed bilayer structures composed of amphiphiles, have attracted considerable attention as functional materials. Structural stability and stimulus responsiveness are required for next-generation functional vesicles. However, there is a dilemma between these properties because the desired membrane structure varies in terms of structural stability and stimulus sensitivity. Herein, we propose a new approach for the development of giant vesicles (GVs) through the molecular design and synthesis of amphiphiles with or without amide linkages, forming hydrogen bonding. From the 1H NMR analysis and fluorescence spectra of environment-responsive probes, intermolecular hydrogen bonding between the amide linkages in the membrane contributed to the enhanced structural stability of the GVs. Moreover, by adding amphiphiles containing a photoresponsive azobenzene moiety to GVs composed of amphiphiles with or without amide linkages, a distinct mechanism of photoresponsive deformation was observed: the former exhibited large and irreversible deformation, while the latter showed a modest and reversible manner due to the photoisomerisation of azobenzene under ultraviolet and subsequent visible light illumination. This difference was also attributed to the membrane structure affected by intermolecular hydrogen bonding. Based on these results, the finding provides a molecular methodology for developing highly functional vesicles.

Access to Document (DOI)

Programmed Fabrication of Vesicle-Based Prototissue Fibers with Modular Functionalities

Kojima T., Asakura K., Gobbo P., Banno T.

Advanced Science 2025

Multicellular organisms have hierarchical structures where multiple cells collectively form tissues with complex 3D architectures and exhibit higher-order functions. Inspired by this, to date, multiple protocell models have been assembled to form tissue-like structures termed prototissues. Despite recent advances in this research area, the programmed assembly of protocells into prototissue fibers with emergent functions still represents a significant challenge. The possibility of assembling prototissue fibers will open up a way to a novel type of prototissue subunit capable of hierarchical assembly into unprecedented soft functional materials with tunable architectures, modular and distributed functionalities. Herein, the first method to fabricate freestanding vesicle-based prototissue fibers with controlled lengths and diameters is devised. Importantly, it is also shown that the fibers can be composed of different specialized modules that, for example, can endow the fiber with magnetotaxis capabilities, or that can work synergistically to take an input diffusible chemical signals and transduce it into a readable fluorescent output through a hosted enzyme cascade reaction. Overall, this research addresses an important challenge of prototissue engineering and will find important applications in 3D bio-printing, tissue engineering, and soft robotics as next-generation bioinspired materials.

Access to Document (DOI)

Photoinduced Shape Changes of Giant Vesicles Comprising Phospholipids and Azobenzene-Containing Cationic Amphiphiles

Noguchi Y., Sasaki S., Liao Y., Matsuo M., Asakura K., Banno T.

Chemistry - An Asian Journal 2025

ISSN 18614728

For the development of new functional materials for various applications, such as drug or gene delivery and environmental remediation, the relationship between function and morphology has been considered an important aspect for controlling affinity to the targets. However, there are only a few reports on this relationship because the molecular strategy for the precise control of vesicle shape has been restricted. Herein, we report the photocontrol of vesicle shape using azobenzene-containing amphiphilic switches. The addition of the photoswitches to vesicles composed of phospholipids yielded non-spherical vesicles. They exhibited reversible deformation between a non-spherical and spherical shape in response to ultraviolet and visible light illumination, respectively. From the results of the 1H NMR analyses, fluorescence spectra of the environmentally responsive probes, and Π-A isotherm measurements, the reversible photoresponsivity can be attributed to the changes in the vesicular membrane structures caused by migration of the photoswitches between the aqueous phase and membrane through their photoisomerization.

Access to Document (DOI)

Engineering pH-Responsive, Self-Healing Vesicle-Type Artificial Tissues with Higher-Order Cooperative Functionalities

Kojima T., Noguchi Y., Terasaka K., Asakura K., Banno T.

Small 20 ( 30 ) 2024.07

ISSN 16136810

Multicellular organisms demonstrate a hierarchical organization where multiple cells collectively form tissues, thereby enabling higher-order cooperative functionalities beyond the capabilities of individual cells. Drawing inspiration from this biological organization, assemblies of multiple protocells are developed to create novel functional materials with emergent higher-order cooperative functionalities. This paper presents new artificial tissues derived from multiple vesicles, which serve as protocellular models. These tissues are formed and manipulated through non-covalent interactions triggered by a salt bridge. Exhibiting pH-sensitive reversible formation and destruction under neutral conditions, these artificial vesicle tissues demonstrate three distinct higher-order cooperative functionalities: transportation of large cargoes, photo-induced contractions, and enhanced survivability against external threats. The rapid assembly and disassembly of these artificial tissues in response to pH variations enable controlled mechanical task performance. Additionally, the self-healing property of these artificial tissues indicates robustness against external mechanical damage. The research suggests that these vesicles can detect specific pH environments and spontaneously assemble into artificial tissues with advanced functionalities. This leads to the possibility of developing intelligent materials with high environmental specificity, particularly for applications in soft robotics.

Access to Document (DOI)

Spot Overtaking of Dyes of Their Chromatographic Development Associated with Solvent Evaporation

Aizawa A., Sumita R., Banno T., Asakura K.

Journal of Oleo Science 73 ( 4 ) 593 - 601 2024

ISSN 13458957

Infiltration of binary solution of hexane and ethanol into chromatography paper associated with their evaporation was found to generate unexpected initial rapid advancement of wicking front followed by its receding and readvancing in our previous research. In the present study, paper chromatography development of hydrophobic dye, Sudan III, and hydrophilic dye, Acid Blue 9, was carried out using binary solutions of hexane and ethanol in open environment, allowing the developing solvent been evaporated. Sudan III was developed with initial rapid advancing wicking front, while Acid Blue 9 was scarcely developed. On the other hand, Acid Blue 9 was developed with the readvancing second wicking front, while the spot of Sudan III scarcely migrated. Thus, the unexpected illusional phenomenon, overtaking the spot of Sudan III by the spot of Acid Blue 9, was observed. The readvancement of the second wicking front was found to be enhanced as increasing the relative humidity in the environment. Surface temperature of the chromatography paper was measured during the chromatographic development in open environment to show that it became lower than the dew point when the experiments were carried out in relatively high humidity. Solubility of Sudan III in a binary solution of ethanol and water remarkably decreased as increasing the content of water. It was thus suggested that the water vapor condensation to induce water mixing into the mobile phase to decrease the solubility of Sudan III to inhibit its chromatographic development to realize the illusional spot overtaking of dyes of their chromatographic development associated with solvent evaporation.

Access to Document (DOI)

Investigation on the Validity of in vitro Sun Protection Factor and Ultraviolet-A Protection Factor Evaluation Method for Sunscreen Samples

Fujishiro M., Yahagi S., Kuroda A., Banno T., Asakura K.

Journal of Oleo Science 73 ( 4 ) 603 - 610 2024

ISSN 13458957

Factors affecting the in vitro Sun Protection Factor (SPF) and Ultraviolet-A Protection Factor (UVA-PF) of sunscreens were analyzed for verifying the validity and reliability of the ISO24443 evaluation method. UV absorbance measurements by different spectrophotometers did not lead to the large difference in in vitro SPF/UVA-PF, although the UV absorbance determined by each spectrophotometer exhibited relatively large difference when it was larger than 2. On the other hand, relatively large difference was found in in vitro SPF/UVA-PF by utilizing European Cosmetic and Perfumery Association (Colipa) 1994 or UV-solar simulated radiation (UV-SSR) for the spectral irradiance. Appropriateness of employing the coefficient of adjustment for the determination of in vitro UVA-PF was also found to be reexamined.

Access to Document (DOI)

Induction for Self-Propelled Motion of Artificial Objects with/without Shape Anisotropy

Banno T., Ueno K., Kojima T., Asakura K.

Journal of Oleo Science 73 ( 4 ) 509 - 518 2024

ISSN 13458957

Motion is an essential feature of living systems. Microorganisms autonomously change their nature in response to slight changes in the surrounding environment induced by external stimuli and exhibit unique motion modes. Various self-propelled objects have been constructed to understand these behaviors. Towards achievement of such purpose, the precise settings of experimental conditions including fabrication of objects with a shape anisotropy have been made attempts in the field of active matter and supramolecular chemistry. This review describes the recent progress in inducing the self-propelled motion of artificial objects. If life-like dynamic behavior such as self-propelled motion can be designed and experimentally induced from molecular properties, it will be easier to control functions expressed as outputs. This will lead to not only a better understanding of the complex functions in living systems, but also the fabrication of exotic materials with life-like properties.

Access to Document (DOI)

In vitro Evaluation Method of UV Protecting Ability of Sunscreens: Clarifying and Overcoming Problems to Develop New Method

Asakura K., Kuroda A., Fujishiro M., Yahagi S.

Journal of Oleo Science 73 ( 2 ) 121 - 134 2024

ISSN 13458957

Factors influencing on in vitro evaluation of UV protecting ability of sunscreens were analyzed. It was found that any factors making the sunscreen layer spatially inhomogeneous, such as directional viscous fingering during the sunscreen application, dewetting of applied sunscreen layer, and the surface roughness of the standard PMMA plate, alter the UV transmittance. New application procedure and new type of flat hydrophilic plate were developed for inhibiting the generation of spatial inhomogeneity in applied sunscreen layer. The method created by the combination of these newly developed technologies succeeded in providing reliable and reproducible in vitro evaluation of UV protecting ability.

Access to Document (DOI)

Bifurcation and Transposition of the Wicking Front of Binary Solutions Infiltrating into Chromatography Paper Associated with Their Evaporation

Aizawa A., Banno T., Asakura K.

Langmuir 39 ( 47 ) 16731 - 16739 2023.11

ISSN 07437463

Nonequilibrium fluid patterns, such as Marangoni contraction, coffee rings, and tears of wine, are generated in binary solutions spread on a substrate during their evaporation. In this study, we observed another type of nonequilibrium behavior exhibited by binary solutions as they infiltrate porous materials and undergo evaporation. A binary solution comprising hexane and ethanol was brought into contact with the chromatography paper to facilitate infiltration into the paper’s pores. Because the experimental setup was in an open environment, infiltration and evaporation occurred simultaneously. The wicking front exhibited an initial rapid advancement, followed by subsequent receding and readvancing. Additionally, the bifurcation of the wicking front after the onset of its readvancement was confirmed by monitoring the temporal evolution of the spatial luminance distribution and temperature distribution on the surface of the chromatography paper. Chromatographic development of a hydrophilic dye was conducted in this experimental setup in an open environment. Additionally, it was confirmed that the receding and readvancing of the wicking front represented the transposition of the bifurcated wicking fronts.

Access to Document (DOI)

Photoinduced phase transition between vesicles and coacervates using low-molecular-weight catanionic amphiphiles

Kojima T., Terasaka K., Asakura K., Banno T.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects) 669 2023.07

ISSN 09277757

Amphiphiles form various molecular self-assemblies in the aqueous phase, such as vesicles and coacervates, depending on molecular properties. Recently, phase transitions between vesicles and coacervates have drawn much attention because the switching between “closed” and “open” compartments could achieve the controllability of molecular sequestrations. We expect that the photoinduced drastic change in the molecular structure of catanionic amphiphiles comprising azobenzene-containing cationic amphiphiles (Azo) and anionic sodium dodecyl sulfate causes the transition. Self-assemblies prepared by a thin-film hydration method were observed using microscopy under UV and subsequent visible-light illumination. Additionally, investigation of selectivity for molecular sequestration and assay of enzymatic reactions in the self-assemblies were conducted. Photoinduced reversible phase transitions between vesicles and coacervates occurred owing to the photoisomerization of Azo. The formed coacervates had selectivity for molecular sequestration. Additionally, the transition achieved fusion of different vesicles via coacervates. Although coacervates are generally known to facilitate enzymatic reactions, the reactions were inhibited in the presence of the formed self-assemblies due to the deactivation of enzymes. Our results represent rapid and non-invasive systems of reversible vesicle–coacervate transitions. Furthermore, the findings provide a new aspect of coacervates in which catanionic low-molecular-weight amphiphiles could act as suppressors of chemical reactions.

Access to Document (DOI)

Factors to control the alignment of surface-treated titanium dioxide powders to maximize performance of sunscreens

Takekawa S., Ohara M., Banno T., Asakura K.

International Journal of Cosmetic Science (International Journal of Cosmetic Science) 45 ( 1 ) 38 - 49 2023.02

ISSN 01425463

Objective: Titanium dioxide powders are contained in a large class of colour cosmetics and sunscreen formulas. When they are used, the formation of a uniform functional powder layer on the skin is an important factor to show their functionality, such as aesthetic and UV protection. Attempts were made to extract the factors that affect the UV shielding ability of the deposited powder layer. Methods: Seven kinds of surface treatments were conducted on nano-sized titanium dioxide powder to modify the surface characteristics. Dispersion samples were prepared by mixing these powders with liquids, such as mixed solutions of cyclopentasiloxane, isododecane, coconuts alkane and dimethicone using a disperser and a bead mill. The dispersions were applied using an applicator on cellulose triacetate film, polycarbonate film and polymethyl pentene film. Laser microscope observation and micro-gloss glossmeter analysis were carried out to assess the flatness of the deposited powder layers, and the UV shielding ability was evaluated using SPF analyser. Results: Factors whose influences on the structure and UV shielding ability of the deposited powder layer being analysed were pseudo-HLB of the powders, liquids for preparing the dispersions and material of the substrates. Higher UV shielding ability was attained when powders having pseudo-HLB at around 6 were employed independent from the kinds of liquids and substrates. Flatness of the deposited layer was found to enhance the UV shielding ability of the UV-B region, while that of the UV-A region was scarcely influenced by the flatness. Employing lower surface tension liquids for preparing the dispersions and materials exhibiting lower polar components of surface free energy as substrates tended to enhance the UV shielding ability. Conclusion: Surface treatments conducted on the powders in this study were found to change UV shielding ability, especially UV-B shielding ability, and the relation between pseudo-HLB and UV shielding ability was scarcely influenced by the kinds of liquids. Both surface tension of liquids and the polar component of surface free energy of substrates affected the UV shielding ability. It was suggested that pseudo-HLB calculated based on chemical structure becomes useful information to choose optimum surface treatment to make uniform powder alignment independent from the surrounding environment.

Access to Document (DOI)

Photoinduced collective motion of oil droplets and concurrent pattern formation in surfactant solution

Kojima T., Kitahata H., Asakura K., Banno T.

Cell Reports Physical Science (Cell Reports Physical Science) 4 ( 1 ) 2023.01

Collective motions are the spontaneous emergence of the ordered movement in living systems. Various constructive approaches have been attempted toward understanding the mechanism. However, few studies have been on the motion induced by biomimetic artificial systems based on molecular conversions. In this study, we report an artificial system of oil droplets in surfactant solutions, wherein collective motion and pattern formation occur concurrently, using the conversion of photoresponsive surfactants. Assembly/dispersion of multiple oil droplets and appearance/disappearance of circular patterns around them occur under UV/visible light illumination, respectively. Moreover, whether the assembled droplets move laterally or not depends on the number of droplets, which is considered analogous to biological organisms in response to population density. These phenomena occur because the photoisomerization of surfactants induces the gradient of interfacial tension, generating specific flow fields around droplets. Our results could be useful for understanding the mechanism of life motion in terms of physicochemical aspects.

Access to Document (DOI)

Synthesis of Mannosylerythritol Lipid Analogues and their Self-Assembling Properties, Recovery Effects on Damaged Skin Cells, and Antibacterial Activity

Kondo T., Yasui C., Miyajima I., Banno T., Asakura K., Fukuoka T., Ushimaru K., Koga M., Saika A., Morita T., Takahashi Y., Hayashi C., Igarashi M., Takahashi D., Toshima K.

Chemistry - A European Journal (Chemistry - A European Journal) 28 ( 55 ) 2022.10

ISSN 09476539

Synthesis of three types of purpose-designed mannosylerythritol lipid (MEL)-D analogues with decanoyl groups, β-GlcEL-D, α-GlcEL-D, and α-MEL-D, was accomplished utilizing our boron-mediated aglycon delivery (BMAD) methods. Their self-assembling properties, recovery effects on damaged skin cells, and antibacterial activity were evaluated. It was revealed, for the first time, that α-GlcEL-D and α-MEL-D only generated giant vesicles, indicating that slight differences in the steric configuration of an erythritol moiety and fatty acyl chains affect the ability to form vesicles. Analogue α-MEL-D exhibited significant recovery effects on damaged skin cells. Furthermore, α-MEL-D exhibited antibacterial activity as high as that for MEL-D, indicating that α-MEL-D is a promising artificial sugar-based material candidate for enhancing the barrier function of the stratum corneum, superior to a known cosmetic ingredient, and possesses antibacterial activity.

Access to Document (DOI)

pH-Sensitive Controlled Motion of Micrometer-sized Oil Droplets in a Solution of Surfactants Containing Fumaric Acid Derivatives

Kaburagi M., Kojima T., Asakura K., Banno T.

Journal of Oleo Science (Journal of Oleo Science) 71 ( 9 ) 1319 - 1326 2022.09

ISSN 13458957

Self-propelled droplets are of considerable interest as an appropriate model for understanding the self-propulsion of objects in the fields of nonequilibrium physics and nonlinear science. Several research groups have reported the monodirectional motion of droplets, that is, chemotaxis, using stimuli-responsive materials. However, the precise control of chemotaxis remains challenging from the perspective of synthetic chemistry because chemotactic motion is primarily induced by the consumption of reactive oil or surfactants. Herein, we report a chemical system containing pH-responsive fumaric acid derivatives, in which the oil droplet exhibited positive chemotaxis over a wide pH range–from basic to acidic conditions. From the measurements of the interfacial tension between the oil and aqueous phases, it was deduced that the positive chemotaxis was due to heterogeneity in the interfacial tension of the droplet surface, which was accompanied by the production of surface-active compounds in the pH gradient in a linear-type channel.

Access to Document (DOI)

Chemotaxis of Oil Droplets and Their Phase Transition to Aggregates with Membrane Structures in Surfactant Solution Containing Metal Salts

Nakayama S., Kojima T., Kaburagi M., Kikuchi T., Asakura K., Banno T.

ChemSystemsChem 4 ( 2 ) 2022.03

The movement of supramolecular self-assemblies has been induced by the application of external stimuli that cause a shift to non-equilibrium conditions. However, few supramolecular chemical systems exist in which multiple different functions are associated with movement. Herein, we observed multiple phase transition of micrometer-sized lauronitrile oil droplets in a solution of cationic surfactants with aniline skeletons in the presence of metal ions. These dynamics include tactic motion and subsequent formation of aggregates with membrane structures, in a linear-type channel. These dynamic behaviors result from variations in the interfacial tension at the droplet surface and the chemical compositions owing to the interactions between system components. The current findings may provide a methodology for designing molecular systems in which multi-step phase transitions of supramolecular self-assemblies are coupled to movement in non-equilibrium conditions.

Access to Document (DOI)

New in vitro SPF Evaluation Method for Hydrophilic Sunscreen Samples

Ikawa K., Aizawa A., Banno T., Fujishiro M., Yahagi S., Kuroda A., Asakura K.

Journal of Oleo Science (Journal of Oleo Science) 71 ( 2 ) 321 - 331 2022.02

ISSN 13458957

A new method was developed for the in vitro sun protection factor (SPF) evaluation of sunscreen samples. A new type of substrate, a hydroxyalkyl cellulose-coated plate, was also prepared specifically for hydrophilic samples. This new substrate was required because hydrophilic samples would be unlikely to wet the surface of the standard cosmetic PMMA UV evaluation plate. A super-hydrophilic quartz plate was prepared by corona-discharge treatment before an aqueous solution of hydroxyalkyl cellulose was spread on it. A flat and uniform hydroxyalkyl cellulose film was subsequently formed through the evaporation of water. Special care was taken to inhibit the generation of spatial non-uniformity. Six hydrophilic sunscreen samples with in vivo SPF values of 56, 55, 52, 25, 15, and 4, were then applied to the prepared hydroxyalkyl cellulose-coated plate, as well as a super-hydrophilic quartz plate and a flat hydrophobic PMMA plate. The thicknesses of the applied layers were determined using a wheel-shaped wet film thickness gauge immediately after the application, and UV transmission was measured using an SPF analyzer. The value of in vitro SPF was calculated from the UV absorbance and the thickness of the layer. For two out of the six samples, PMMA plate could not be available, as the samples were unable to wet the PMMA surface. Relatively small differences were observed between the in vitro SPF values when the super-hydrophilic and hydroxyalkyl cellulose-coated plates were used. Samples exhibiting higher in vivo SPF were also associated with higher in vitro SPF values, although a linear relationship was not observed. In contrast to the super-hydrophilic plate whose half-life of the super-hydrophilicity is only approximately five days, the hydrophilicity of the hydroxyalkyl cellulose-coated plate scarcely varied during six months of storage. Finally, a simplified evaluation method was also proposed. The validity of the method was verified through a ring test where three researchers employed this method in different laboratories at three independent organizations.

Access to Document (DOI)

Self-Assembling Properties and Recovery Effects on Damaged Skin Cells of Chemically Synthesized Mannosylerythritol Lipids

Kondo T., Yasui C., Banno T., Asakura K., Fukuoka T., Ushimaru K., Koga M., Minamikawa H., Saika A., Morita T., Takahashi D., Toshima K.

ChemBioChem (ChemBioChem) 23 ( 2 ) 2022.01

ISSN 14394227

Mannosylerythritol lipids (MELs), which are one of the representative sugar-based biosurfactants (BSs) produced by microorganisms, have attracted much attention in various fields in the sustainable development goals (SDGs) era. However, they are inseparable mixtures with respect to the chain length of the fatty acids. In this study, self-assembling properties and structure-activity relationship (SAR) studies of recovery effects on damaged skin cells using chemically synthesized MELs were investigated. It was revealed, for the first time, that synthetic and homogeneous MELs exhibited significant self-assembling properties to form droplets or giant vesicles. In addition, a small difference in the length of the fatty acid chains of the MELs significantly affected their recovery effects on the damaged skin cells. MELs with medium or longer length alkyl chains exhibited much higher recovery effects than that of C18-ceramide NP.

Access to Document (DOI)

Pathway-Dependent Phase Transitions of Supramolecular Self-assemblies Containing Cationic Amphiphiles with Azobenzene and Disulfide Groups

Sawada D., Asakura K., Banno T.

Chemistry - A European Journal (Chemistry - A European Journal) 27 ( 55 ) 13840 - 13845 2021.10

ISSN 09476539

There have been several attempts to construct supramolecular chemical systems that mimic the phase transitions in living systems. However, most of these phase transitions are one-to-one and induced by one stimulus or chemical; there have been few reports on the pathway-dependent phase transition of supramolecular self-assemblies in multi-step. To induce multistep phase transitions, molecular crystals were prepared that contained a cationic amphiphile bearing azobenzene and disulfide groups. A reducing agent caused the crystals to become vesicles, and adjacent, non-touching vesicles fused under UV and subsequent visible light. Adding a reducing agent to the worm-like aggregates that were generated after UV irradiation of the original crystals resulted in the growth of sheet-like aggregates. 1H NMR and fluorescence anisotropy measurements showed that a series of phase transitions was induced by changes in the phase structures from molecular conversions of the reactive amphiphiles. The multiple pathway-dependent phase transitions of supramolecular self-assemblies can provide a methodology for developing new stimuli-responsive materials that exhibit the desirable properties under specific circumstances from a systems chemistry viewpoint.

Access to Document (DOI)

How to control powder alignment to maximize functionality and performance of color cosmetics and sunscreen

Takekawa S., Ohara M., Banno T., Asakura K.

Journal of Oleo Science (Journal of Oleo Science) 70 ( 8 ) 1081 - 1091 2021.08

ISSN 13458957

Control of powder alignment is essential for maximizing the functionality of color cosmetics and sunscreens. Various surface treatments were applied to nanosized titanium dioxide to modify their surface characteristics. Such modifications can be used to control the behavior of dispersions in cosmetics, enabling them to align uniformly. The powders were mixed with solvents and applied to a cellulose triacetate film. The features of powder alignment on the film were evaluated using several approaches. When the type of surface treatment changed by varying the weight ratio, there was no significant correlation between its alignment and treatment. However, when we focused on the pseudo-HLB each treated pigment, their alignments were correlated. It was confirmed that the powders subjected to the appropriate surface treatment combinations from the pseudo-HLB standpoint made it possible to align uniformly and create a smooth coating film. As a result, it has a high UV-shielding ability. The surface-treated powders in this study were found to change the UV shielding ability and surface roughness of the layer formed when they were formed by spreading the sample powder dispersion and drying of the film. It was suggested that the pseudo-HLB, which is calculated based on the chemical structure after the surface treatment process, is useful for choosing the optimum surface treatment to create a uniformly aligned pigment layer.

Access to Document (DOI)

pH-Tolerant giant vesicles composed of cationic lipids with imine linkages and oleic acids

Sawada D., Hirono A., Asakura K., Banno T.

RSC Advances (RSC Advances) 10 ( 56 ) 34247 - 34253 2020.09

Giant vesicles (GVs) have attracted attention as functional materials because they can encapsulate both hydrophilic and hydrophobic compounds. For next generation functional GVs, both tolerance and stimuli-sensitivity are needed. So far, vesicles tolerant to acidic or basic conditions were generated using a mixture of cationic lipids and fatty acids. Here, to create functional GVs that are tolerant to a wide pH range but sensitively respond at below a specific pH, the behaviour of GVs composed of a cationic lipid with an imine bond and oleic acid was investigated. Even though the GVs prepared by the film swelling method were tolerant to strongly acidic conditions, GVs without oleic acid gradually shrank, accompanied by the generation of oil droplets at the same pH. 1H NMR analysis revealed that during hydration of the film, the imine bond hydrolysed to provide a cationic surfactant and an oil component in the presence of oleic acid due to its own Lewis basicity, suggesting the dissociation of oleic acid. The results of fluorescence spectroscopy using an environment-responsive probe and IR spectroscopy indicated that the GV tolerance originated from the intermolecular interactions of cationic lipids and anionic oleate. This journal is

Access to Document (DOI)

Temperature-Dependent Dynamics of Giant Vesicles Composed of Hydrolysable Lipids Having an Amide Linkage

Tameyuki M., Hiranaka H., Toyota T., Asakura K., Banno T.

Langmuir (Langmuir) 35 ( 52 ) 17075 - 17081 2019.12

ISSN 07437463

Various amphiphiles including surfactants and lipids have been designed and synthesized to improve and create new functionalities. In particular, the emergence of cell-like behaviors of giant vesicles (GVs) composed of synthetic lipids has drawn much attention in the development of chemical models for cells. The aim of this study was to measure temperature-dependent morphological changes of GVs induced by fragmentation and subsequent growth using hydrolysable cationic lipids having an amide linkage. Results from differential scanning calorimetry, fluorescence spectroscopy using an environment-responsive probe, and confocal Raman microscopy showed that the dynamics observed were due to changes in the vesicle membrane, including variation in the lipid composition, induced by thermal stimulation.

Access to Document (DOI)

Start of Micrometer-Sized Oil Droplet Motion through Generation of Surfactants

Kasuo Y., Kitahata H., Koyano Y., Takinoue M., Asakura K., Banno T.

Langmuir (Langmuir) 35 ( 41 ) 13351 - 13355 2019.10

ISSN 07437463

Self-propelled motion of micrometer-sized oil droplets in surfactant solution has drawn much attention as an example of nonlinear life-like dynamics under far-from-equilibrium conditions. The driving force of this motion is thought to be induced by Marangoni convection based on heterogeneity in the interfacial tension at the droplet surface. Here, to clarify the required conditions for the self-propelled motion of oil droplets, we have constructed a chemical system, where oil droplet motion is induced by the production of 1,2,3-triazole-containing surfactants through the Cu-catalyzed azide-alkyne cycloaddition reaction. From the results of the visualization and analysis of flow fields around the droplet, the motion of the droplets could be attributed to the formation of flow fields, which achieved sufficient strength caused by the in situ production of surfactants at the droplet surface.

Access to Document (DOI)

Surface structures of cosmetic standard poly methyl methacrylate UV evaluation plates and their influence on the in vitro evaluation of UV protection abilities of cosmetic sunscreens

Kuroda A., Sakai K., Yahagi S., Mukawa T., Sato N., Nakamura N., Maezawa D., Masaki H., Banno T., Asakura K.

Journal of Oleo Science (Journal of Oleo Science) 68 ( 2 ) 175 - 182 2019.02

Research paper (scientific journal), Joint Work, Accepted, ISSN 13458957

© 2019 by Japan Oil Chemists’ Society. Cosmetic standard poly methyl methacrylate (PMMA) UV evaluation plates, i.e., roughened PMMA plates, are used in the EU and the US for the in vitro evaluation of UV protection abilities of sunscreen, such as in vitro UVA-PF and critical wavelength for the Broad-spectrum approval. In our previous studies, inhomogeneity in the thickness of a pseudo-sunscreen layer applied on a flat quartz plate was observed to alter UV transmission. Thus, the surface roughness of the standard plates should have a significant influence on the in vitro evaluation. In the present study, we have analyzed the surface structures of three cosmetic standard PMMA UV evaluation plates: Helioplates HD6 (Sa = 6 µm) and ISO plates (Ra = 2 and 5 µm). A decamethylcyclopentasiloxane and 2-propanol-mixed solvent solution of acrylsilicone resin was prepared, and the solution was added dropwise onto the plates. After the evaporation of the solvents, the plates were cut and the cross section was analyzed using SEM-EDS. The distribution of silicon atoms at the cross-section suggested that the maximum depth of penetrating of acrylsilicone resin was larger than Ra for all the standard plates, and the surface structure was significantly different for each standard plate. In addition, cracks into which the acrylsilicone resin deeply penetrated were observed on the surface of some plates. Clear-solution-type pseudo-sunscreen samples in which UV absorbers and acrylsilicone resin were dissolved were deposited on the standard roughened PMMA plates. It was observed that the addition of acrylsilicone resin drastically changed the net UV transmission. The degree to which the hollows of the roughened surface were filled with the pseudo-sunscreen samples determined the variation of UV transmittance.

Access to Document (DOI)

Hydrophilicity of the substrate surface under the applied sunscreen layer changes in vitro UV protection efficacies

Kouichi Asakura, Akihiro Kuroda

IFSCC Magazine (IFSCC) 21 53 - 57 2018.08

Research paper (scientific journal), Joint Work, Accepted

Locomotion Mode of Micrometer-Sized Oil Droplets in Solutions of Cationic Surfactants Having Ester or Ether Linkages

Hirono A., Toyota T., Asakura K., Banno T.

Langmuir (Langmuir) 34 ( 26 ) 7821 - 7826 2018.07

Research paper (scientific journal), Joint Work, Accepted, ISSN 07437463

© 2018 American Chemical Society. Micrometer-sized self-propelled oil droplets under a far-from-equilibrium condition have drawn much attention because of their potential as a dynamic model for the chemical machinery in living organisms. To clarify the effect of interactions between the system components (surfactant, oil, and water) on the locomotion mode of droplets, we investigated the behaviors of oil droplets composed of n-heptyloxybenzaldehyde (HBA) in solutions of cationic surfactants having or not having an ester or an ether linkage. It was observed that in solutions of cationic surfactants having an ester or an ether linkage, spherical HBA droplets self-propelled by changing their direction frequently. On the other hand, when this functional group is absent, a slow self-propelled motion of the oil droplets concurrent with the evolution of aggregates on their surface was observed. From the results of measurement of interfacial tension and assessment of self-emulsification, we determined that the attractive interactions of cationic surfactants without an ester or an ether linkage with HBA are stronger than those having the linkage. The difference in the locomotion mode of oil droplets is probably explained from the viewpoint of the interactions among the system components.

Access to Document (DOI)

Effect of freeze–thaw treatment on the precipitation of octyl β-D-Galactoside hemihydrate crystal from the aqueous solution

Ogawa S., Takahashi I., Koga M., Asakura K., Osanai S.

Journal of Oleo Science (Journal of Oleo Science) 67 ( 5 ) 627 - 637 2018

Joint Work, Accepted, ISSN 13458957

© 2018 by Japan Oil Chemists’ Society. Cryogenic treatment, like the freeze–thaw process, has been reported to be effective in modifying the physicochemical properties of polymeric hydrogels. However, not much attention has been paid to this process in terms of the precipitation of surfactant–water systems. In this study, two effective cryogenic methodologies were successfully reported to alter the physicochemical properties of a precipitate of an octyl β-D-galactoside (Oct-Gal)–water system. First, hyperrapid cooling (i.e., cooling at 30℃/min) was found to be an effective type of cryogenic treatment: the phase transition temperature (T K ) and enthalpy at the phase transition (ΔH K ) between the crystal-dispersed phase and the sol (micelle) phase significantly decreased. In addition, cryogenic treatment in the presence of electrolytes, such as NaCl, NaBr, and CsCl, was effective even in the absence of the hyperrapid cooling condition. The hyperrapid cooling or the addition of certain electrolytes was considered to prevent the precipitation of the Oct-Gal hemihydrate crystals prior to the complete freezing of ice and the electrolyte/ice eutectic. Hence, the size of the aggregated crystals prepared by the above-mentioned effective cryogenic treatments seemed to be decreased compared with that of the normal precipitated crystals, thereby changing T K and ΔH K . Thus, two basic methodologies for the modification of the physicochemical properties of the crystal-dispersed phase of surfactant–water systems are discussed.

Access to Document (DOI)

Coagel prepared from aqueous octyl β-D-galactoside solution

S. Ogawa, M. Koga, K. Asakura, I. Takahashi, S. Osanai

J. Surfact. Det. 20 ( 1 ) 255 - 261 2017

Research paper (scientific journal), Joint Work, Accepted

Phototactic behavior of self-propelled micrometer-sized oil droplets in a surfactant solution

S. Kaneko, K. Asakura, T. Banno

Chem. Commun. 53 2237 - 2240 2017

Research paper (scientific journal), Joint Work, Accepted

Self-propelled oil droplets and their morphological change to giant vesicles induced by a surfactant solution at low pH

T. Banno, Y. Tanaka, K. Asakura, T. Toyota

Langmuir 632 ( 37 ) 9591 - 9597 2016

Research paper (scientific journal), Joint Work, Accepted

Controlled polymerization of acrylonitrile proceeded along with the Belousov-Zhabontinsky oscillator by changing its stirring conditions

Y. Furue, K. Okano, T. Banno, K. Asakura

Chem. Phys. Lett. 645 210 - 214 2016

Research paper (scientific journal), Joint Work, Accepted

Oligosaccharide-based surfactant / citric acid buffer system stabilizes lactate dehydrogenase during freeze-drying and storage without the addition of natural sugar

S. Ogawa, R. Kawai, M. Koga, K. Asakura, I. Takahashi, S. Osanai, S

J. Oleo Sci. 65 ( 6 ) 525 - 532 2016

Research paper (scientific journal), Joint Work, Accepted

Problems on the evaluation of the critical wavelength of sunscreens for “Broad Spectrum” approval brought on by viscous fingering during sunscreen application

M. Wakabayashi, K. Okano, T. Mukawa, D. Maezawa, H. Masaki, A. Kuroda, K. Asakura

Photochem. Photobiol. 92 ( 4 ) 637 - 643 2016

Research paper (scientific journal), Joint Work, Accepted

Deformable self-propelled micro-object comprising underwater oil droplets

T. Banno, A. Asami, N. Ueno, H. Kitahata, Y. Koyano, K. Asakura, T. Toyota

Sci. Rep. 6 31292 2016

Research paper (scientific journal), Joint Work, Accepted

Photoresponsive stripe pattern in achiral azobenzene liquid crystals

Kunihiko Okano, Satoshi Aya, Fumito Araoka, Haruki Obara, Shiori Sato, Takashi Yamashita, Hideo Takezoe, Kouichi Asakura

ChemPhysChem 16 ( 1 ) 95 - 98 2015.01

Research paper (scientific journal), Joint Work, Accepted

Degree of maintenance of lactate dehydrogenase (LDH) activity during freeze/thaw process highly depends on hydrophobic chain length of synthetic mono-tailed glycolipid stabilizer

S. Ogawa, R. Kawai, M. Koga, K. Asakura

Cryobiology and Cryotechnology 61 89 - 94 2015

Research paper (scientific journal), Joint Work, Accepted

Lyotropic behavior of a mono-tailed glycolipid assembly during solidification and melting of electrolyte/ice eutectic systems

Shigesaburo Ogawa, Kouichi Asakura, Shuichi Osanai

Chem. Pharm. Bull. 62 ( 12 ) 1180 - 1184 2014.12

Research paper (scientific journal), Joint Work, Accepted

High-strength gel actuator driven by a photothermal effect

Kunihiko Okano, Aya Nogami, Kouichi Asakura

Polymer J. 46 ( 12 ) 827 - 830 2014.12

Research paper (scientific journal), Joint Work, Accepted

Coexistence effect of UVA absorbers to increase their solubility and stability of supersaturation

Mayu Endo, Tsubasa Mukawa, Nobumasa Sato, Daisuke Maezawa, Yutaka Ohtsu, Akihiro Kuroda, Misaki Wakabayashi, Kouichi Asakura

Int. J. Cosmet. Sci. 36 ( 6 ) 546 - 552 2014.12

Research paper (scientific journal), Joint Work, Accepted

Problems of in vitro SPF measurements brought about by viscous fingering generated during sunscreen applications

Kanae Fujikake, Shizuka Tago, Raphael Plasson, Ryo Nakazawa, Kunihiko Okano, Daisuke Maezawa, Tsubasa Mukawa, Akihiro Kuroda, Kouichi Asakura

Skin Pharmacol. Physiol. 27 ( 5 ) 254 - 262 2014.07

Research paper (scientific journal), Joint Work, Accepted

Thermotropic and glass transition behaviors of n-alkyl β-D-glucosides

OGAWA SHUGESABURO, ASAKURA KOUICHI, OSANAI SHUICHI

RSC Adv. 3 21439 - 21446 2013

Research paper (scientific journal), Joint Work, Accepted

Synchronization of Oscillatory Chemiluminescence with Pulsed Light Irradiation

S. Takayama, K. Okano, K. Asakura

Chem. Phys. Lett. 555 300 - 305 2013

Research paper (scientific journal), Joint Work, Accepted

Freezing and Melting Behavior of an Octyl b-D-glucoside-water Binary System - Inhibitory Effect of Octyl b-D-glucoside on Ice Crystal Formation

S. Ogawa, K. Asakura, S. Osanai

Phys. Chem. Chem. Phys. 14 ( 47 ) 16312 - 16320 2012

Research paper (scientific journal), Joint Work, Accepted

Turing Pattern Formation by the CIMA Reaction in a Chemical System Consisting of Quaternary Alkyl Ammonium Cationic Groups

K.Asakura, R. Konishi, T. Nakatani, T. Nakano, M. Kamata

J. Phys. Chem B 115 ( 14 ) 3959 - 3963 2011

Research paper (scientific journal), Joint Work, Accepted

Reactivity of Alanylalanine Diastereoisomers in Neutral and Acid Aqueous Solutions: A Versatile Stereoselectivity

R. Plasson, M. Tsuji, M. Kamata, K. Asakura

Orig. Life Evol. B 41 ( 5 ) 413 - 435 2011

Research paper (scientific journal), Joint Work, Accepted

Preparation of Highly Water-repellent Surface by Spontaneous Formation of Double Scale Roughness Pattern

P. Joly, A. Kuroda, K. Asakura

J. Oleo Sci. 59 ( 2 ) 89 - 94 2010

Research paper (scientific journal), Joint Work, Accepted

Preparation and Characterization of Organic-inorganic Microcomposite Cylindrical GRIN Lens

E. Nihei, J. Oomoto, S. Kimura, K. Asakura

Polym. J. 42 ( 12 ) 941 - 946 2010

Research paper (scientific journal), Joint Work, Accepted

Glass Transition Behavior of Octyl Beta-D-glucoside and Octyl Beta-D-thioglucoside/water Binary Mixtures

S. Ogawa, K. Asakura, S. osanai

Carbohydr.Res. 345 ( 17 ) 2534 - 2541 2010

Research paper (scientific journal), Joint Work, Accepted

An Organic-Inorganic Hybrid Composite as a Coating Agent

A. Kuroda, P. Joly, N. Shibata, H. Takeshige, K. Asakura

J. Am. Oil Chem. Soc. 85 ( 6 ) 549 - 553 2008.06

Research paper (scientific journal), Joint Work, Accepted

Preparation of photonics polymers by spontaneous frontal polymerization

Asakura, K.; Takata, A.; Oomoto, J.; Nihei, E.

Polymer Preprints 49 ( 1 ) 805 - 806 2008

Research paper (conference, symposium, etc.), Joint Work

Fabrication of Spatially Periodic Double Roughness Structures by Directional Viscous Fingering and Spinodal Dewetting for Water-Repellent Surfaces

A. Kuroda, T. Ishihara, H. Takeshige, K. Asakura

J. Phys. Chem. B 112 ( 4 ) 1163 - 1169 2008

Research paper (scientific journal), Joint Work, Accepted

Analysis of the Mechanism of Asymmetric Amplification by Chiral Auxiliary Trans-1,2-diaminocyclohexane Bistriflamide

K. Asakura, Y. Isoda, D. K. Kondepudi, T. Yamaguchi

Chirality 20 ( 8 ) 919 - 923 2008

Research paper (scientific journal), Joint Work, Accepted

結晶成長フロントにおける散逸構造としてのキラル対称性の破れ

朝倉浩一

日本結晶成長学会誌 34 ( 2 ) 63 - 68 2007

Research paper (scientific journal), Single Work

Emergence of Homochirality in Far-from-equilibrium Systems: Mechanism and Role in Prebiotic Chemistry

R. Plasson, D. K. Kondepudi, H. Bersini, A. Commeyras, K. Asakura

Chirality 19 ( 8 ) 589 - 600 2007

Research paper (scientific journal), Joint Work, Accepted

Experimental Evidence and Theoretical Analysis for the Chiral Symmetry Breaking in Growth Front of Conglomerate Crystal Phase of 1,1'-Binaphthyl

K. Asakura, R. Plasson, D. K. Kondepudi

Chaos 16 037116 2006.09

Research paper (scientific journal), Joint Work, Accepted

Stable Non-racemic States in Far-from-equilibrium Systems as Origin of Homochirality

Raphael Plasson, Kouichi Asakura, Dilip K. Kondepudi

Origins of Life 36 ( 3 ) 282 - 283 2006.06

Research paper (conference, symposium, etc.), Joint Work, Accepted

Chiral Symmetry Breaking in Growth Front of Conglomerate Crystal Phase

Kouichi Asakura 、Raphael Plasson、 Dilip K. Kondepudi

Origins of Life 36 ( 3 ) 284 - 285 2006.06

Research paper (conference, symposium, etc.), Joint Work, Accepted

Control of Spatial Periodicties of Dewetting Structures of Oleo-Liquid Films

A. Kuroda, H. Takeshige, K. Asakura

J. Oleo. Sci. 55 277 - 282 2006.06

Research paper (scientific journal), Joint Work, Accepted

Three-Dimensional Description of the Spontaneous Onset of Homochirality on the Surface of a Congromerate Crystal Phase

R. Plasson, K. Asakura, D. K. Kondepudi

J. Phys. Chem. B 110 8481 - 8487 2006.04

Research paper (scientific journal), Joint Work, Accepted

A New Perspective on the Mechanism of Asymmetric Amplification

K. Asakura, T. Yamamoto, S. Inoue, S. Osanai, D. K. Kondepudi

Chem. Phys. Lett. 406 312 - 317 2005

Research paper (scientific journal), Joint Work, Accepted

周期凹凸構造の自己組織化を利用した表面処理技術

朝倉浩一, 石井宏明

金属 75 ( 8 ) 766 - 770 2005

Research paper (scientific journal), Joint Work

Kinetic Model for Chiral Symmetry Breaking Transition in Growth Front of Conglomerate Crystal Phase

K. Asakura, Y. Nagasaka, S. Osanai, D. K. Kondepudi

J.Phys. Chem. B 109 1586 - 1592 2005

Research paper (scientific journal), Joint Work, Accepted

Synthesis and characterization of novel amphiphiles containing amino acid and carbohydrate

ASAKURA KOUICHI, A. Abe, S. Osanai

Journal of Surfactants and Detergents ( 7 ) 297 - 303 2004.07

Research paper (scientific journal), Joint Work, Accepted

Spontaneous Frontal Polymerization -Propagating Front Spontaneously Generated by Locally Autoaccelerated Free-radical Polymerization

K. Asakura, E. Nihei, H. Harasawa, A. Ikumo, S. Osanai

Nonlinear Dynamics in Polymeric Systems, ACS Symposium Series No. 869; Pojman, J. A.; Tran-Cong-Miyata, Q. Eds.; American Chemical Society: Washington, DC, p.135-146(2004) ( 869 ) 135 - 146 2004

Research paper (scientific journal), Joint Work, Accepted

Chiral Symmetry Breaking Transition in Growth Front of Crystal Phase of 1, 1'-Binaphthyl in its Supercooled Melt

K. Asakura, T. Soga, T. Uchida, S. Osanai, D. K. Kondepudi

Chirality ( Vol.16 ) 131 - 136 2004

Research paper (scientific journal), Joint Work, Accepted

ナノテクを利用したラスティングサンスクリーン剤の開発

朝倉浩一, 黒田章裕

フレグランスジャーナル, Vol. 2003 ( 2003 ) 49 - 54 2003

Research paper (scientific journal), Joint Work

Role of latent heat in chiral symmetry breaking transition in the crystallization of 1,1-binaphthyl

K. Asakura, M. Hayashi, S. Osanai

Chirality ( Vol.15 ) 238 - 241 2003

Research paper (scientific journal), Joint Work, Accepted

Spontaneous Generation of Hot and Reacted Region to Form Propagating Front in a Reaction System of Free-radical Polymerization of Methyl Methacrylate

Asakura, K.; Ikumo, A.; Harasawa, H.; Osanai, S.; Nihei, E.

Polymer Preprints 43 823 - 824 2002.08

Joint Work, Accepted

メタクリル酸メチルの重合における反応の自己促進効果は、トロムスドルフ効果のみならず、反応熱の蓄熱効果も大きな要因であり、したがって反応器のサイズが反応進行度に大きな影響を与えることを報告した。また、適当なサイズとすることで、反応中心部に高温で反応が進行した部位が出現し、フロンタル重合が中心部から周囲へと進行していく形で反応が完了することを紹介した。

Polymeric Antioxidants. V. Ortho Methylene-bridged and Direct-linked Sesamol Oligomers

Asakura, K.; Honda, E.; Matsumura, S.; Osanai, S.; Kawada, K.

Journal of Oleo Science 51 ( 2 ) 97 - 102 2002.02

Research paper (scientific journal), Joint Work, Accepted

Probability Distributions of Enantiomeric Excess in Unstirred and Stirred Crystallization of 1, 1’-Binaphthyl Melt

Asakura, K.; Soga, T.; Uchida, T.; Osanai, S.; Kondepudi, D. K.

Chirality 14 ( 1 ) 85 - 89 2002.01

Research paper (scientific journal), Joint Work, Accepted

有機基質の劣化防止に対する新規物質及び新規技術の開発に関する研究

朝倉浩一

オレオサイエンス ( Vol.12 ) 767 - 773 2002

Research paper (scientific journal), Single Work

Chiral Autocatalysis, Spontaneous Symmetry Breaking, and Stochastic Behavior

Kondepudi, D. K.; Asakura, K.

Accounts of Chemical Research 34 ( 12 ) 946 - 954 2001.11

Research paper (scientific journal), Joint Work, Accepted

Adsorption Properties of Amphiphilic Polyoxyalkylenated Dimethylpolysiloxane Derivatives on Keratin

Asakura, K.; Iida, A.; Kitagata, R.; Yoshida, A.; Osanai, S.; Kuroda, A.

Journal of Surfactants and Detergents 4 ( 4 ) 375 - 378 2001.10

Research paper (scientific journal), Joint Work, Accepted

Condition for Chiral Asymmetry Generation in the Preparation of the Chiral Octahedral Cobalt Complex

Asakura, K.; Osanai, S.; Kondepudi, D. K.

Chirality 13 ( 8 ) 435 - 440 2001.08

Research paper (scientific journal), Joint Work, Accepted

自発的キラル非対称性の発現と成長

朝倉浩一

化学と教育 49 ( 8 ) 476 - 479 2001.06

Research paper (scientific journal), Single Work

Chirally Autocatalytic Reaction Performed in Highly Supersaturated Conditions

Asakura, K.; Kurihara, K.; Ikumo, A.; Tanaka, A.; Miura, T.; Ozawa, T.; Kushibe, Y.; Osanai, S.; Kondepudi, D. K.

Macromol. Symp. ( vol.160 ) 7 - 13 2000.10

Research paper (scientific journal), Joint Work, Accepted

Chirally Autocatalytic Reaction Peformed in Highly Supersaturated Condition

朝倉浩一，井雲昭仁，栗原和志，小山内州一，Dilip K. Kondepudi

International Conference on Nonlinear Dynamics in Polymer Science and Related Fields 3-6 2000.03

Joint Work, Accepted

正八面体ビスエチレンジアミン型コバルト錯体の合成反応において観察されるキラル自動触媒過程は、その生成物の過飽和度がある閾値を越えた時点で機能するようになることを見出した。高過飽和度溶液中において形成されたクラスターが、キラル自動触媒種として機能したという仮定に基づいたシミュレーションの結果は、実験的に観察された自動触媒反応速度と過飽和度の関係に一致した。

Random Chiral Asymmetry Generation by Chiral Autocatalysis in Far-from-Equilibrium Reaction System

朝倉浩一，井雲昭仁，栗原和志，小山内州一，Dilip K. Kondepudi

J. Phys. Chem. A, Vol. 104 2689-2694 2000.03

Research paper (scientific journal), Joint Work

局所的濃度の自動触媒的成長が拡散速度を上回ると，ゆらぎの成長により反応システムは平衡から離れる。キラル自動触媒系が機能するならば、このような場合に生成物の光学純度がランダムにばらつくことが予想される。正八面体ビスエチレンジアミン型コバルト錯体の合成反応におけるキラル非対称性の発現は、このような機構によるものであることを実験及び理論の両面から証明した。

Chiral Symmetry Breaking in Stirred Crystallization of 1,1'-Binaphthyl Melt

Dilip K. Kondepudi，Jennifer Laudadio，朝倉浩一

J. Am. Chem. Soc. 121 1999.02

Research paper (scientific journal), Joint Work

Auto-inhibitory Factors of p-Cresol Oxidative Coupling and Their Elimination

朝倉浩一，中田芳昭，坂詰裕之，小山内州一

J. Jpn. Oil Chem. Soc. 48 1999.02

Research paper (scientific journal), Joint Work

塩化第二鉄水溶液中での， p-クレゾールの酸化カップリング反応による直接結合型オリゴマーの合成反応において，生成される塩化水素と塩化第一鉄は反応を抑制し、この反応は自動阻害系であることを見い出した。ＨＳＡＢ則で中間の塩基に分類されるピリジンは，中間の金属イオンに分類され本反応の競争阻害因子として機能する塩化第一鉄と安定な錯体を形成し，変換率を向上させることを報告した。（５頁）

Formation of the Intermediate, Aquohydroxobis(ethylenediamine)cobalt(III) complex, in the Preparation of cis-Bromoamminebis(ethylenediamine)cobalt(Ⅲ) Bromide by the Reaction of Bis[bis(ethylenediamine) cobalt(Ⅲ)-μ-dihydroxo] diaquocobalt(Ⅱ) Sulfate with A

朝倉浩一，井上和也，小山内州一，Dilip K. Kondepudi

J. Coord. Chem. 46 1998.12

Research paper (scientific journal), Joint Work

Mechanism of Chiral Asymmetry Generation by Chiral Autocatalysis in the Preparation of Chiral Octahedral Cobalt Complex

朝倉浩一，Dilip K. Kondepudi，Reesheda Martin

Chirality 10 1998.04

Research paper (scientific journal), Joint Work

キラル自動触媒的非対称性の発現が起こる正八面体ビスエチレンジアミン型コバルト錯体の合成反応において，一方の異性体結晶を予め添加して反応を行った際に，激しく撹拌した場合ほど同じ異性体が優先的に合成される割合が高まることを見い出した。また，この反応系を動力学的に解析し，コンピューターシミュレーションにより実験結果を再現させ，キラル自動触媒機構についての理論的な検討を行った。（５頁）

Emergence of Chiral Symmetry Breaking by Chirally Autocatalytic Secondary Nucleation

朝倉浩一，小林佳代，水澤良徳，小澤武廣，三浦兼仁，田中亜希子，櫛部圭紀，小山内州一

Recent Res. Devel. in Pure & Applied Chem. 1 ( 1 ) 1997.12

Research paper (scientific journal), Joint Work

キラリティーを有する母結晶からの二次核生成により生成する子結晶は，母結晶と同じキラリティーを有する。反応系内において生成物の結晶化が進行し，さらにその結晶化がキラル自動触媒的二次核生成による進行するために，反応初期の統計学的偏差による両異性体量の差が増幅されて，自発的に一方の異性体が優先的に生成されてくる例を幅広く総説した。（１０頁）

(+)589-Λ-Amminebromobis (ethylenediamine-N,N')cobalt (III) Dibromide

中川博雄，大場茂，朝倉浩一，三浦兼仁，田中亜希子，小山内州一

Acta Cryst. C 45 1997.02

Research paper (scientific journal), Joint Work

Selective Dimerization of p-Cresol in the Presence of Micelles of Cationic Surfactants

朝倉浩一，井奥章，四津貴之，小山内州一

J. Jpn. Oil Chem. Soc. 45 1996.09

Research paper (scientific journal), Joint Work

水溶液中での塩化第二鉄によるp-クレゾールの酸化カップリング反応を，アルキルトリメチルアンモニウムブロミド型陽イオン性界面活性剤の存在下にて行うと，生成されたp-クレゾールの二量体はそのミセル中に高選択的に取り込まれるため，酸化反応系からは除去されて三量体への成長が抑制され，二量体生成の選択性が向上することを報告した。（３頁）

二次核生成によりキラル選択性が増幅される反応系

朝倉浩一，小山内州一

日本結晶学会誌 38 1996.06

Research paper (scientific journal), Joint Work

キラル自動触媒系が機能する反応システムにおいては，反応初期の統計学的偏差による両異性体量の差が増幅され，自発的に一方の異性体が優先的に生成されてくる可能性が有る。二次核生成により自己複製が可能で，さらに自身の構成要素である鏡像異性体分子を認識出来るキラル結晶が反応系に生成してくるために，自発的に一方の異性体が高選択的に生成する自動触媒的キラル対称の破れの現象について総説した。（６頁）

Selective Oxidative Dimerization of p-Cresol in Water-Organic Solvent Two Phase Systems

朝倉浩一，中田芳昭，坂詰裕之，小山内州一

J. Jpn. Oil Chem. Soc. 45 1996.05

Research paper (scientific journal), Joint Work

Regulations for the Product Distribution of the Oxidative Coupling of p-Cresol by Cyclodextrins

朝倉浩一，渡辺智也，本田栄敏，小山内州一

Chem. Lett. 1996 1996.04

Research paper (scientific journal), Joint Work

Generation of an Optically Active Cobalt Complex by Chiral Autocatalysis

朝倉浩一，小林佳代，水澤良徳，小澤武廣，小山内州一，吉川貞雄

Physica D 84 1995.07

Research paper (scientific journal), Joint Work

非対称な正八面体ビスエチレンジアミン型コバルト錯体の合成反応において，光学活性を有する錯体が自発的に合成されてくることがあることを見い出した。極少量の一方の異性体結晶を予め添加して反応を行うと同じ異性体が優先的に合成されてくることから，反応初期の統計学的偏差による両異性体量の差がキラル自動触媒的に増幅されるため，自発的に一方の異性体が優先的に生成されてくると考察した。（７頁）

Selective Oxidative Coupling of p-Cresol Producing an ortho-ortho Direct-linked Dimer

朝倉浩一，本田栄敏，小山内州一

Chem. Lett. 1995 1995.06

Research paper (scientific journal), Joint Work

Synthesis and Antimicrobial Properties of Amphiphilic Sugar Derivatives Containing Sulfur and Nitrogen

矢後和夫，膳昭之助，河田和雄，内堀毅，　朝倉浩一，松村秀一

J. Antibact. Antifung. Agents 22 1994.04

Research paper (scientific journal), Joint Work

Antimicrobial Properties of ortho-ortho Direct-linked Phenolic Oligomers

松村秀一，塩谷陽俊，朝倉浩一，河田和雄，内堀毅

J. Antibact. Antifung. Agents 22 1994.01

Research paper (scientific journal), Joint Work

Polymeric Antioxidants. IV. Phenolic Oligomers Having Direct Linkage at ortho Positions

朝倉浩一，塩谷陽俊，本田栄敏，松村秀一

J. Jpn. Oil Chem. Soc. 42 1993.09

Research paper (scientific journal), Joint Work

ペルオキシダーゼを用いたフェノール類の過酸化水素による酸化重合により，オルト位同士が直接結合したオリゴマーを合成した。これらオリゴマーのラードの自動酸化に対する抗酸化性はそれぞれのモノマーと同程度であるが，テトラリンに対する抗酸化性は優れていることを見い出した。特に重合中の水酸基の損失の少なかったオリゴマーについては，顕著な抗酸化性の向上が認められたことを報告した。（５頁）

Effects of Preparation Temperature on the Hydroperoxide Retention Properties of Cyclodextrin Polymer Gels

朝倉浩一，川口宏和，叶内敬之，田中信敏，吉川貞雄，鈴木孝治

J. Jpn. Oil Chem. Soc. 42 1993.04

Research paper (scientific journal), Joint Work

シクロデキストリンを，25及び50℃にてアルカリ中でエピクロロヒドリンと反応させてポリマーゲルを合成し，液体カラムクロマトグラフィーの固定相として用い，ヘキサンを溶出溶媒としてテトラリンとテトラリンモノヒドロペルオキシドの分離を試みたところ，25℃で合成したポリマーゲルは分離に有効であったが，50℃で合成したものはほとんど分離能を示さなかった。（４頁）

Affinity of Cyclodextrins to Hydroperoxides

朝倉浩一，田中信敏，叶内敬之，松村秀一，吉川貞雄

J. Jpn. Oil Chem. Soc. 41 1992.03

Research paper (scientific journal), Joint Work

シクロデキストリン水溶液中に，酸化劣化したテトラリン及び不飽和脂肪酸メチルを加えて撹拌すると，それぞれの過酸化物と選択的に複合体を形成し析出するため，過酸化物の除去に有効であることを見い出した。テトラリンに対してはβ-シクロデキストリン，オレイン酸メチル及びリノレン酸メチルに対してはγ-シクロデキストリン，リノール酸メチルに対してはα-シクロデキストリンが最も有効であることを報告した。（４頁）

Biological Activities of Phenolic Oligomers (II) Antimicrobial Activity of Fractionated Phenol Oligomers and Alkylidene-bridged Phenol Oligomers

河田和雄，内堀毅，渡辺昭一郎，朝倉浩一，松村秀一，吉川貞雄

J. Antibact. Antifung. Agents 18 1990.08

Research paper (scientific journal), Joint Work

ゲル濾過カラムクロマトグラフィーにより，異なった数平均分子量を有するフラクションに分離されたフェノール類の線状全オルトメチレン結合型オリゴマーは，分子量が高いものを除いては，グラム陽性菌，グラム陰性菌，及び真菌に対する優れた抗菌性を示すことを見い出した。また，アルキリデン結合型のオリゴマーは，グラム陽性菌及び真菌に対する抗菌性に優れることを報告した。（４頁）

Biological Activities of Phenolic Oligomers (I) Relationship Between the Degree of Addition-condensation of Phenolic Oligomers and their Antimicrobial Activity

内堀毅，河田和雄，渡辺昭一郎，朝倉浩一，松村秀一，吉川貞雄

J. Antibact. Antifung. Agents 18 1990.05

Research paper (scientific journal), Joint Work

一連のフェノール類のメチレン結合型オリゴマーを合成し，これらオリゴマーがグラム陽性菌，グラム陰性菌，及び真菌に対して優れた抗菌性を示すことを見い出した。また，全オルトメチレン結合のフェノールの２，３，４，及び６量体を合成し，その抗菌性を測定したところ，４量体はグラム陽性菌に対して，また６量体は真菌に対して，特に活性に優れることを報告した。（４頁）

Recognition of Tetralin Hydroperoxide by Cyclodextrins

朝倉浩一，田中信敏，松村秀一，吉川貞雄

Chem. Lett. 1989 1989.11

Research paper (scientific journal), Joint Work

シクロデキストリン水溶液中にテトラリンを加え撹拌するとその複合体が析出するが，その際に酸化劣化したテトラリンを用いると，その過酸化物と選択的に複合体を形成して析出するため，その除去に有効であることを見い出した。また，α-，β-，及びγ-シクロデキストリンの中では，β-シクロデキストリンが複合体形成における過酸化物選択性が最も高いことを報告した。（５頁）

Antioxidant Effect and Antimicrobial Activity of Phenolic Sulfides

朝倉浩一，松村秀一，吉川貞雄，河田和雄，内堀毅

J. Amer. Oil Chem. Soc. 66 1989.06

Research paper (scientific journal), Joint Work

ビニルフェノールとチオール類のマイケル付加及びラジカル付加により，フェノール性水酸基とスルフィド基の両方を有する誘導体を合成し，その抗酸化性及び抗菌性について検討を行った。マイケル付加体はラードに対して非常に優れた抗酸化性を示すが，ラジカル付加体はほとんど活性を示さないことを見い出した。また，両種の誘導体とも優れた抗菌性を示すことを報告した。（５頁）

Antioxidant and Antimicrobial Effect of Phenolic Sulfides

朝倉浩一，松村秀一，吉川貞雄，河田和雄，内堀毅，渡辺昭一郎

Proceedings of ISF-JOCS World Congress 1988 p. 556-562 ( 1988 ) 556-562 1989.06

Research paper (scientific journal), Single Work, Accepted

高分子抗酸化剤の研究（第３報）ポリビニルフェノールについて

松村秀一，笠間秀徳，朝倉浩一，吉川貞雄

油化学 37 1988.08

Research paper (scientific journal), Joint Work

高分子抗酸化剤の研究（第２報）線状及び環状メチレン結合フェノールオリゴマーについて

朝倉浩一，松村秀一，吉川貞雄，笠間秀徳

油化学 37 1988.04

Research paper (scientific journal), Joint Work

線状及びノボラック型のフェノール-アルデヒド型のオリゴマーを合成し，ラードの自動酸化に対する抗酸化性を測定したところ，数平均分子量は600〜1000，オルト位結合比は90％程度のものが抗酸化性に優れることを見い出し，メチレン結合の部位にメチル基を導入すると活性が低下することを報告した。また，環状のオリゴマーは全く抗酸化性を示さないことを報告した。（６頁）

高分子抗酸化剤の研究（第１報）全オルトメチレン結合線状アルキルフェノールオリゴマーについて

阿部芳郎，松村秀一，朝倉浩一，笠間秀徳

油化学 35 1986.09

Research paper (scientific journal), Joint Work

線状全オルト結合型のアルキルフェノール-ホルムアルデヒド型オリゴマーを合成し，ラードの自動酸化に対する抗酸化性を測定したところ，BHTと同等以上の優れた抗酸化性を有することを見い出した。そして，パラ位にメトキシル基を有する誘導体には，特に優れた抗酸化性が認められ，またいずれのオリゴマーについても，数平均分子量が600〜1000のものが高い抗酸化性を示すことを報告した。（５頁）

　 Previous page - Next page 　