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Gut in Form: Filme von hochverzweigten Polycumaraten können unter Einstrahlung von UV ‐ Licht eine reversible [2+2] ‐ Cycloaddition eingehen und verhalten sich wie photomechanische Elastomere. Ausgehend von der Form A werden die photonisch und thermisch gespeicherten Formen B und C erhalten. Durch Bestrahlen mit Licht kann die Ausgangsform wiederhergestellt werden (siehe Bild; Tg=Glasübergangstemperatur). [ABSTRACT FROM AUTHOR]

Poly(4-hydroxycinnamic acid) (P4HCA), poly(3-hydroxycinnamic acid) (P3HCA), poly(3-methoxy-4-hydroxycinnamic acid) (PMHCA) and poly(3,4-dihydroxycinnamic acid) (PDHCA) were synthesized by the thermal poly-condensation of the corresponding monomers, which are lignin precursors, coumaric acid derivatives consisting of cinnamoyl groups and different position and number of OH groups. The solubility of the homo-polymers in organic solvents decreased in the order of P3HCA > PDHCA > P4HCA > PMHCA. The wide angle X-ray diffraction (WAXD) results indicated that P4HCA or PMHCA with p-OH group had higher crystallinity, in contrast to P3HCA or PDHCA with m-OH group which had lower crystallinity. Crossed-polarizing microscopy suggested that P4HCA had the nematic liquid crystal properties at 220°C and PDHCA showed birefringence properties at 200°C. In cell-adhesion tests, PDHCA showed the highest cell adhesion (ca. 70%), whereas P3HCA, P4HCA and PMHCA had 50, 18 and 10% cell adhesion, respectively. The coumaric acid derivative homo-polymers can be useful as cell adhesion controllable thermotropic polymers for biomedical and environmental fields. [ABSTRACT FROM AUTHOR]

The present study focuses on nanoparticles composed of amphiphilic poly(γ-glutamic acid) (γ-PGA) as potential protein carriers. Amphiphilic graft co-polymers composed of γ-PGA as the hydrophilic backbone and L-phenylalanine ethylester (L-PAE) as the hydrophobic segment were synthesized by grafting L-PAE to γ-PGA using water-soluble carbodiimide (WSC). Due to their amphiphilic properties, the γ-PGA-graft-L-PAE co-polymer formed monodispersed nanoparticles in water. The particle size of the nanoparticles composed of γ-PGA-graft-L-PAE (γ-PGA nanoparticles) was about 200 nm and showed a highly negative zeta potential. To evaluate their potential applications as multifunctional protein carrier, we prepared protein-entrapped γ-PGA nanoparticles by encapsulation, covalent immobilization or physical adsorption methods. For this purpose, 11 different proteins with various molecular weights and isoelectric points (pI values) were used as model proteins. The encapsulation of the protein into the nanoparticles was observed for all tested proteins. The amount of protein covalently immobilized or adsorbed onto the nanoparticles showed different tends based on the molecular weight and pI of each protein. Positively charged proteins could be adsorbed onto the negatively charged nanoparticles by electrostatic interaction. Moreover, it was found that enzyme-encapsulated nanoparticles showed higher enzymatic activity than surface-immobilized nanoparticles. These results indicated that the enzymatic activity of the enzyme-entrapped nanoparticles was significantly affected by the conjugation method, and that encapsulation was the optimal method for the conjugation of proteins and nanoparticles. It is expected that the γ-PGA nanoparticle will have great potential as multifunctional carriers in pharmaceutical and biomedical applications, such as drug and vaccine delivery systems. [ABSTRACT FROM AUTHOR]

Abstract: A novel thermotropic liquid-crystalline biocopolymer, poly{trans-4-hydroxycinnamic acid (4HCA: trans-coumaric acid)-co-lithocholic acid (LCA)}, was synthesized by a thermal polycondensation of 4HCA and LCA. When the LCA composition of P(4HCA-co-LCA) was 0, 5, 7, 23, 27, and 45mol%, the copolymers showed a nematic liquid-crystalline phase. The melting point of the copolymers was 120–250°C depending on the LCA composition, and showed a maximum at 7mol%. Wide angle X-ray diffraction (WAXD) analyses showed a typical diffraction pattern of a hexagonal arrangement for 0, 7, 23, and 27mol% LCA composition, which were cooled from a nematic melt. The other polymers showed no distinct diffraction. In particular, the copolymer of 7mol% LCA composition showed four distinct diffractions corresponding to spacings with a reciprocal ratio of 1, √3, 2, and √7, indicating the highest structural ordering of all copolymers prepared here. The results of the cell adhesion and static contact angle tests suggest that the 7mol% LCA composition copolymer had the highest hydrophobicity and cell adhesion ability, which was easily controlled by altering in feed. We conclude that the structural ordering may have a significant correlation with cell adhesion activity. [Copyright &y& Elsevier]