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A simultaneous measurement system of wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and Raman or transmission- type infrared spectroscopy was developed by us. Its purposes is to clarify the static and dynamic structural changes of polymer materials subjected to the various external condition changes. Some examples described here include the study of the stretch-induced reorientation phenomenon of a-axially-oriented polyethylene, the study of structural change in photo-induced solid-state polymerization reaction of muconic acid ester monomer crystal, the study of the two-stage high-temperature phase transitions of aliphatic nylons, the study of stress-induced crystalline phase transition of an oriented poly(tetramethylene terephthalate) sample and its relation to the higher-order structural change, and the study of structural regularization process of poly(L-lactic acid) in the isothermal crystallization of the meso phase. These case studies in the clarification of hierarchical structural changes of polymer materials have proven that the simultaneous measurement systems can be useful to examine the structural changes in polymer systems. [ABSTRACT FROM AUTHOR]

To deliver genes, we used a complex made from DNA and cationic lipids that is called "lipoplex". In this Study, we prepared lipoplexes consisting of an aromatic amine compound and various short single chains of DNA with the different lengths and bases, and evaluated the structures of the lipoplexes by small-angle X-ray scattering (SAXS) and circular dichroism (CD). SAXS showed that the transition from a spherical to lamellar structure was observed between dA3 and dA4 when dA was added. dT showed the same tendency between dT4 and dT5. The CD analysis revealed that each oligonucleotide forms a different conformation after the complexation. dA maintained the conformation in the lipoplex, but dT broke it up. These differences are attributed to the hydrophobicity of the each base structure between dA and dT. These data indicate that the each oligonucleotide has a different strength to maintain the stacking of base. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) has three crystal structures: forms I, II, and III. Each structure was fabricated by solvent casting using various solvents. In this study, we demonstrated how to fabricate forms I, II, and III using one solvent (hexamethylphosphoric triamide), The results and revealed that the crystal structure of PVDF depended on the evaporation rate of the solvent. Eventually, Form I was formed into when the evaporation rate was slow, Form II was formed when it was fast, and form III was formed at the evaporation rate between form I and II. [ABSTRACT FROM AUTHOR]

The evolution processes of regular structure in isothermal crystallization phenomena of crystalline polymers have been investigated from the viewpoints of molecular level, crystal lattice, and higher-order structure on the basis of time-dependent infrared spectral data and synchrotron small- (SAXS) and wide-angle X-ray scattering (WAXD) data. The polymers treated here were isotactic polypropylene (iPP), nylon 10/10 and polyoxymethylene (POM). In the case of iPP, the formation and growing processes of regular helical segments in the molten state are described by utilizing the concept of critical sequential length for infrared bands. Combination of these spectroscopic data with the SAXS and WAXD data clarifies the formation process of domains consisting of regular helical segments, the increment of correlation of neighboring domains, and the development of stacked lamellar structure, during which the remarkable growth of crystal lattices consisting of regular helices occurs in parallel. In the case of nylon 10/10, weak hydrogen bonds are formed between amide groups even in the molten state. Once the isothermal crystallization starts to occur, these more-or-less correlated domains built up by the hydrogen bonds are formed followed by the formation of crystal lattices consisting of relatively regular methylene segments. Such growth is quite different from the case of iPP crystallization. The study of POM is based on the observation of infrared bands intrinsic to the folded chain crystals (FCC) and extended chain crystals (ECC). From the time-resolved measurements of these infrared bands as well as the SAXS and WAXD in the isothermal crystallization process of POM, we clarified that the lamellar structure of FCC morphology is formed at first. Then some new lamellae are formed in between these original lamellae, resulting in the formation of ECC parts in which the regular helices pass through the several neighboring lamellae as taut tie chains. [ABSTRACT FROM AUTHOR]

We synthesized a cationic lipid benzyl amine derivative bearing a primary amine as the head group and evaluated its transfection efficiency as a DNA carrier. A lipoplex (complex of DNA and lipid micelle) was prepared by mixing BA and two neutral colipids (DOPE and DLPC). When we compared the transfection efficiency at various compositions, we found that B-lipoplex (BA/DOPE/DLPC = 1/2/1) was the most efficient while A-lipoplex (BA/DLPC = 1/1) showed no transfection. We compared A-lipoplex with B-lipoplex by use of SAXS, fluorescence spectrum of ethidium bromide and pyrene. These results indicated that A-lipoplex formed a lamellar or cylinder structure within which DNA molecules were trapped in the lipid alkyl chain, while B-lipoplex formed cylinders where DNAs were intercalated between the lipid micelle cylinders. [ABSTRACT FROM AUTHOR]