Structures and physicochemical properties of lipids such as fatty acids, alcohols, acylglycerols and steroids in their two- or three-dimensional states were studied through the measurements of surface pressure (π), surface-molecular area (A), vapor-pressure osmosis, radioactivity (R), self-diffusion coefficient (D), density, viscosity, near-infrared spectroscopy (NIR), ¹³C-NMR spin-lattice relaxation time (T₁), ESR, SEM, DSC, X-ray diffraction and small-angle neutron scattering (SANS). Following results are obtained : (1) π-A and R-A relationships indicate that the explanation, being widely believed, of the reaction occurred in the oleic acid or the trioleylglycerol monolayer on the aqueous KMnO₄ solution is incorrect. (2) By using the LB film of ³H-labelled fatty acid, the upper limit of the neutrino mass was determined. In addition, by using the LB film of ¹⁴C-labelled fatty acid, a new type of crystal-transformation process was found, in which fatty-acid crystal transforms from its unstable state to its stable one by the transfer of the fatty acid molecules through the vapor phase. (3) Fatty acids always exist as their dimers in their liquid state and mostly in non-polar solvents; the dimers are the units of the molecular movements in the molten liquid and in solvents. T₁ results clearly showed the internal molecular movements of the dimers. In addition, D and SANS results indicated that two different kinds of fatty acids in their binary mixture make only each homodimers. (4) Furthermore, the study on the liquid structure of fatty acids such as cis-6-, cis-9-, cis-11-,trans-9-octadecenoic acids and stearic acid indicated that these fatty-acid dimers construct the clusters resemble to the smectic-liquid crystal in the liquid state. The clusters determine the physicochemical properties of the liquid of the fatty acid.

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Amino acids are indispensable materials for living system at the same time are versatile molecules to be converted to functional materials. Various N-acylamino acids are synthesized from amino acids and their feature properties as amphoteric materials are investigated in terms of structure and function relationship. The evolution of self-organization of amino acid based chiral surfactants from soft assembly to hard mesophase are investigated. As a soft assembly, chiral micelles and lyotropic cholesteric liquid crystals are introduced. And such soft self organized chiral structure was utilized as a template to create chiral mesoporous silica.

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Polyunsaturated fatty acids (PUFA) play an important role for the regulation of various biological reactions and maintenance of cell homeostasis as a major component of membrane lipids and also exert numerous beneficial functions as bioactive substances and their precursors. For further application of multi-functional PUFA as foods, medicals and materials, molecular mechanism for biosynthesis of PUFA was investigated by identification and elucidation of molecular action of fatty acid desaturases and elongases in mammal and fungus, a physiological function of PUFA was studied in allergic mouse model, and potential of new PUFA-producing microorganisms was examined for industrial use.

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