Published papers

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.

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

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.

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.

非平衡開放系における自己組織化は、ミセル及び結晶のような熱力学的安定性が保証されている構造が形成される機構とは全く異なることを説明した上で、この概念により、鏡像異性体の一方による化学系の独占が可能であることの証明ができることを解説した。

自発的キラル非対称性の発現が見られる、キラル正八面体型コバルト錯体の合成反応においては、生成物が高過飽和な状態でキラル自触媒系が機能することを説明した。また、反応系の不均一性が反応の促進に大きく寄与することを明らかにした。

ジメチルポリシロキサン型両親媒性ポリマーについて、その香粧品材料としての機能を検討するために、ケラチン表面に対する吸着性を測定した。その結果、パーフルオロアルキル基の導入により、ポリマーの吸着性が向上することを見い出した。

キラル対称性の破れが、キラル自触媒系により起こる機構を概説した。また、これまでに理論的及び実験的に検討を行なってきたキラル自触媒系について、近年の研究の進展を総説すると共に、本分野における今後の様々な課題を提案した。

1, 1’-ビナフチル融液中の結晶化において、生成する多結晶体の光学純度は、過冷却度を低下させることで増加することを見い出した。また、結晶化系を撹拌する速度を上昇させることにより、キラル対称性の破れが起こることを報告した。

ゴマ種子中に存在するセサモールは抗酸化性を有するが、それをメチレン結合あるいは直接結合させてオリゴマー化させることで、抗酸化性がさらに向上することを見い出した。特にメチレン結合型オリゴマーは、優れた抗酸化性を示すことを報告した。

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。