Polymer Journal

Yoshida, Ryo

doi: 10.1038/pj.2010.75pmid: N/A

In this study, polymers with an autonomous self-oscillating function were examined to obtain a novel biomimetic polymer. The author succeeded in developing a novel self-oscillating polymer and gel by using the oscillating reaction called the Belousov–Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer is composed of a poly(N-isopropylacrylamide) network in which the catalyst for the BZ reaction is covalently immobilized. Under the coexistence of reactants, the polymer undergoes spontaneous cyclic soluble–insoluble changes or swelling–deswelling changes (in the case of gel) without any on–off switching of external stimuli. Several kinds of functional material systems using self-oscillating polymer and gel, such as biomimetic actuators and mass transport surfaces, are expected.

Maruyama, Ken; Hirabayashi, Toshiaki; Kudo, Hiroto; Nishikubo, Tadatomi

doi: 10.1038/pj.2010.74pmid: N/A

The synthesis and photo-polymerization of hyperbranched polyesters (HBPEs) containing terminal methacryloyl groups (HBPE-MA) were examined. Polycondensations of 1,4-bis(chloromethyl)benzene with 1,3,5-benzenetricarboxylic acid using 1,8-diazabicyclo[5.4.0]undec-7-ene as a base were performed to give the soluble HBPEs in satisfactorily high yields. Furthermore, HBPE-MA was synthesized by the reaction of HBPE with methacrylic acid. The photo-induced radical polymerization of HBPE-MA was performed in the presence of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-2-one (Irgacure 907), which acts as a photoinitiator in the solid film state and yields an insoluble cured film upon ultraviolet irradiation.

Okuda, Hitoshi; Seto, Ryota; Koyama, Yasuhito; Takata, Toshikazu

doi: 10.1038/pj.2010.77pmid: N/A

Poly(arylene sulfone)s (PASs) containing a 9,9′-spirobifluorene (SBF) skeleton in the main chain were synthesized in high yields by the oxidation of the corresponding poly(arylene thioether)s. The PASs exhibited good thermal stability (T g 257–370 °C, T d5>400 °C under nitrogen) and showed high solubility in ordinary organic solvents, such as CHCl3, N-methylpyrrolidone (NMP) and N,N-dimethyl formamide (DMF). All films of PASs showed higher refractive indices in the range of 1.65–1.67 at 587.6 nm than those of commercially available polysulfone, whereas they hardly showed birefringence. These excellent optical and thermal properties are derived from the C 2 symmetry and high aromatic component of the SBF moiety.

Miyasaka, Makoto; Fujiwara, Yusuke; Kudo, Hiroto; Nishikubo, Tadatomi

doi: 10.1038/pj.2010.79pmid: N/A

Hyperbranched polysiloxanes were synthesized by polyhydrosilylation of silsesquioxane derivatives and vinyl derivatives in the presence of Karstedt's catalyst. The hyperbranched polymers (HBPs) with M n=5.2 × 103–9.8 × 104 were soluble in common solvents and exhibited good thermal stability. HBPs based on double-decker-shaped silsesquioxane showed a large thermal–optical coefficient compared with the corresponding linear polymer. The refractive index values of the polymers obtained tended to decrease with the increasing structure size of the co-monomers.

Ghoul, Yassine El; Martel, Bernard; Achari, Ahmida El; Campagne, Christine; Razafimahefa, Lova; Vroman, Isabelle

doi: 10.1038/pj.2010.80pmid: N/A

Polypropylene (PP)-knitted fabrics were finished with β-cyclodextrin (β-CD) and crosslinked with citric acid (CTR). The polyCTR–β-CD polymer-coated fibers were wash resistant. We report that the rate of immobilized CD was controlled by temperature and curing time. The weight increase of the fabrics after modification with native β-CD and CTR reached 30 %wt. The treated PP supports were dyed using disperse, acid and reactive dyes. Standard tests of wash fastness (shade change and staining) were conducted and showed that all dyes were fixed, because of inclusion complexation with immobilized cavities on the one hand and sorbed hydrogen and ionic bonds that occurred between the polyCTR–β-CD coating and the tested dyestuffs on the other.

Kudo, Yasuya; Sakuragi, Mina; Hashida, Satoshi; Kuwahara, Rempei; Ishi-I, Tsutomu; Masunaga, Hiroyasu; Sakurai, Kazuo

doi: 10.1038/pj.2010.72pmid: N/A

Small- and wide-angle X-ray scattering from an organogel system made from discotic triazine triamide (TRI) in octanol was carried out using a synchrotron X-ray source to provide scattering profiles for a wide range of scattering vectors, of range 0.050 nm−1 <q <20 nm−1, where q is the magnitude of the scattering vector. The analyses of the profiles revealed the following features: (1) the amorphous nature of the molecular stacking at a distance of 0.32 nm; (2) the presence of a semiflexible rod-like scattering object with a radius of 1.3 nm and a Kuhn length of 55 nm; and (3) branching of the cylinder formed in the gel state. These findings lead to the conclusion that the aggregated TRI functions in the manner of a semiflexible polymer chain in octanol and that the polymer-chain-like behavior of TRI cylinders is the origin of the gel nature of this system.

Lee, Eun-Hye; Tsujimoto, Takashi; Uyama, Hiroshi; Sung, Moon-Hee; Kim, Kwang; Kuramitsu, Seiki

doi: 10.1038/pj.2010.71pmid: N/A

The effects of poly(γ-glutamic acid) (γPGA), a water-soluble poly(amino acid), on the enzyme activity and stability have been investigated. The activity of carbonic anhydrase (CA) was distinctly improved in the presence of 0.30–2.0% γPGA at pH 7. γPGA was also effective to enhance the activity of lipase and α-amylase. γPGA efficiently suppressed denaturation of the enzyme by the thermal treatment and repeated freeze–thaw process. The interaction of γPGA and CA was investigated by using fluorescence probe-labeled protein. The Michaelis–Menten kinetics on the CA-catalyzed hydrolysis of p-nitrophenyl acetate in the absence or presence of γPGA were performed, which demonstrated that the enhancement of the CA activity by γPGA is ascribed to the increase of the catalytic constant k cat.

Sasaki, Yoshihiro; Nomura, Yuta; Sawada, Shin-ichi; Akiyoshi, Kazunari

doi: 10.1038/pj.2010.73pmid: N/A

Polysaccharide nanogels have been demonstrated to aid the refolding processes of chemically or thermally denatured proteins, a function that is similar to that of natural molecular chaperones. In this study, we examined the possibilities of using the nanogel chaperone system to mediate protein folding in a cell-free (in vitro) protein synthesis system containing transcription/translation factors. High-performance liquid chromatography showed that a polysaccharide nanogel comprising cholesteryl group-bearing pullulan (CHP) trapped unfolded or partially folded green fluorescent protein (GFP) expressed in the cell-free system. The protein release and refolding processes, which are induced by ATP in natural molecular chaperone systems, were also simulated by methyl-β-cyclodextrin (M-β-CD). The CHP nanogels dissociate on complexation with M-β-CD to yield dissociated CHP. Thus, the dissociation of the CHP nanogel–protein complex subsequently allows for the release and folding of GFP. The folding kinetics in the presence of the CHP nanogel and M-β-CD was comparable to that of spontaneous folding in the absence of CHP/M-β-CD, indicating that the CHP nanogels did not affect protein synthesis in the cell-free system, providing correctly folded active proteins.

Kaneko, Daisaku; Thi le, Nguyen Quyen; Shimoda, Tatsuya; Kaneko, Tatsuo

doi: 10.1038/pj.2010.78pmid: N/A

For the purpose of an electronic paper application, alginate/Ca hydrogel particles having a diameter of a few micrometers used with Titanium Black (TB), which has a diameter of ∼1 μm, for visualization purposes were prepared by mixing an aqueous sodium alginate solution with TB into an aqueous CaCl2 solution. In order to increase their absolute zeta potential ∣ζ∣ for demonstrating good electric responsive behavior, micro-hydrogel particles were rinsed instantaneously by different concentrations of Na2CO3 solution. Through this procedure, the absolute value of the zeta potential ∣ζ∣ in pure water increased from ∣ζ∣=1.3 mV for the minimum value to ∣ζ∣=73 mV for the maximum value with an upon increasing Na2CO3 concentration. Micro-hydrogel particles were set between electrodes in pure water, their electro-responsive behavior was examined under an applied electric field and their position was analyzed using an optical microscopy. It was found that micro-hydrogel particles with a high absolute zeta potential ∣ζ∣ could oscillate from the anode to the cathode with a corresponding frequency, and threshold absolute zeta potential ∣ζ∣ was found to be between 1.3 and 39 mV.

Miyata, Takashi; Asami, Noriko; Okita, Yurie; Uragami, Tadashi

doi: 10.1038/pj.2010.76pmid: N/A

Permeation of model drugs with different molecular weights through a bioconjugated membrane having antigen–antibody complexes as reversible crosslinks was investigated in the absence and presence of a target antigen. The bioconjugated membrane regulated the drug permeation in response to the concentration of a target antigen. This paper focuses on the effect of the molecular size of the drugs on controlled permeability of the antigen-responsive membrane.[Figure not available: see fulltext.]