社団法人高分子学会

Molecular chaperones in living systems selectively interact with a non-native protein by hydrophobic interaction to prevent irreversible aggregation and release the protein in its refolded form with the aid of ATP and another co-chaperone. The chaperone inspired us to explore new concepts for assisting protein refolding/stabilizing proteins and for developing protein delivery system. Design and application of nanogels or liposomes-based chaperon inspired systems are described. Self-assembled amphiphilic nanogels act as artificial molecular chaperones which show effective trapping and stabilizing proteins or enzymes. The chaperon-like function is useful for protein delivery in medical applications such as cancer and nasal vaccines. Liposome chaperone in cell-free membrane protein synthesis is an attractive approach in proteo-liposome engineering. Polymer Preprints, Japan 2010, 59, 7.

Our recent studies demonstrated that a variety of Lewis and protonic acids induced living cationic polymerization of vinyl ethers and styrenes. The addition of a suitable base and appropriate selection of an acid catalyst were found to be crucial to the success of the following various types of living polymerization: (1) new living initiating systems exhibiting characteristic polymerization behavior such as ultrafast living polymerization, (2) heterogeneously-catalyzed living polymerization with metal oxides or heteropolyacids, (3) synthesis of well-controlled alternating copolymers. Furthermore, this living cationic polymerization permitted the selective preparation of new polymers with pendant imidazolium salts exhibiting UCST-type phase separation in water and LCST-type phase separation in organic solvents. Polymer Preprints, Japan 2010, 59, 58.

Reverse Osmosis (RO) membranes can remove more than 99% of Na+ and Cl- ions from seawater. It is difficult to observe the structure of RO membranes by TEM or SEM, because these membranes are very dense. Pores with a range of 0.3 ~ 0.4 nm radius were observed by Positron Annihilation Lifetime Spectroscopy (PALS). It was found that the removal rate of boric acid and pore size has a good correlation. Also pore size measured by PALS is in agreement with the results determined by Molecular Dynamics simulation using data of solid state 13C NMR measurements. Based on this fundamental knowledge, advanced RO membranes have been developed and are used worldwide. Polymer Preprints, Japan 2010, 59, 34., Preprints of 28th Annual Meeting, the Membrane Society of Japan, (2006), p.33.

A unique complex between a cationic enzyme and polyamine graft copolymers was found to show the regulation and preservation of the enzymatic activity even after heat treatment. Poly[2-(N,N- diethylamino)ethyl methacrylate]-graft-poly(ethylene glycol) (PEAMA-g-PEG) suppressed the enzymatic activity of lysozyme completely without any conformational change, indicating complex formation and the capping the active site of lysozyme by PEAMA-g-PEG. The addition of an anionic polymer, poly(acrylic acid) (PAAc), recovered the inhibited enzymatic activity of the lysozyme/PEAMA-g-PEG complex completely. It is interesting to note that even after heating the lysozyme with PEAMA-g-PEG for 20 min at 98 淸, the addition of PAAc recovered 80 % enzymatic activity of lysozyme. CD spectral analysis clearly indicated that the irreversible inactivation of lysozyme induced by the heat treatment was suppressed by the complex formation with PEAMA-g-PEG. The 1st FAPS Polymer Congress, Abstract 22D18 (2009).

This paper reports the latest researches on gel materials using photonic approach, named "GEL PHOTONICS". Latest high-strength gels overcome brittleness due to the inhomogeneities built in their network structure. However, the inhomogeneities still prevent precise characterization of their network structures by scattering methods. A new approach is to take advantage of the ensemble-averaged structure characterization with scanning microscopic light scattering, named "SMILS", in order to clarify the toughening mechanism of anomalously robust double- network gels. Also, the photonic approach makes it possible to create free-shape robust gels having the shape of blood vessel, and to develop a deformable robust gel lens mimicking the crystalline lens in the eye. Polymer Preprints, Japan 2010, 59, 113.

The potential (energy level) gradient plays an important role in several fields of chemistry that is related to charge transfer. However, there are only very few approaches to construct an intramolecular potential gradient in large polymeric systems. For example, the simple connection of several molecules with several energy levels is one possible approach, but the synthesis, the inter- and intra-molecular interactions, and the unstable conformation of the molecule presents a significant problem. To solve these problems, we focused on rigid dendritic structures as a backbone to construct an intramolecular potential gradient, and revealed that dendritic carbazoles have an outer-layer electron rich potential gradient. This potential gradient spontaneously emerges by the electron withdrawal of each carbazole. This simple approach to construct an intramolecular potential gradient will be an important step to allow the design and control of an intramolecular potential structure. Polymer Preprints, Japan 2010, 59, 163., JACS, 2009, 131, 2244.

Cholesteric liquid crystals (CLCs) have found much attention as a distributed feedback laser cavity and their application to wavelength-tunable dye lasers. For the efficient continuous wave (CW) lasing, lasing threshold must be lowered essentially to zero. We designed new pyrene and anthracene derivatives for LC dye lasers. The threshold value of one of the 1,3,6,8-tetraarylpyrene derivatives is as low as 1/20 of that of DCM in CLC distributed feedback lasers. This pyrene dye exhibits good solubility for the CLC matrix and very high absorption coefficients (e > 72700 (392 nm)) and high quantum yields (F > 0.90). We suggest a strategy to obtain an ideal dye in view of the luminous efficiency and radiative decay rate. Polymer Preprints, Japan 2010, 59, 1577.

The synthesis of stereocomplex poly(lactic acid) is one of the central topics in industry as well as in academia. We previously reported that achiral homosalen-Al complexes catalyzed the stereoselective polymerization of racemic lactide (rac-LA) to afford the stereocomplex poly(lactic acid).¹ However, there are some disadvantages to overcome. We therefore synthesized some polymer-supported ligands and prepared the corresponding catalysts, which stereoselectively polymerized rac-LA. After the polymerization, the polymer- supported ligand was easily recovered from the polymer solution by filtration and was reusable, and the colorless poly(rac-LA) solution in toluene was obtained as the filtrate. Polymer Preprints, Japan 2010, 59, 529. ¹(a) J. Am. Chem., Soc. 2002, 124, 5938. (b) Polym. J., 2004, 36, 261. (c) Chem.ﾑEur. J., 2007, 13, 4433.