Jun‐Ichi Kadokawa

Facile preparation of glycogen‐based polysaccharide gel materials was carried out by phosphorylase‐catalyzed chain elongation of glycogen using glucose 1‐phosphate (Glc‐1‐P). The resulting solution after the enzymatic reaction gradually turned into a hydrogel form, which was probably caused by formation of junction zones based on the double helix structure of the elongated amylose chains among the glycogen molecules. Furthermore, lyophilization of the hydrogel resulted in formation of a glycogen‐based xerogel. The mechanical properties of the hydrogels and xerogels were affected by the amount of glycogen and the Glc‐1‐P/glycogen ratio in the feed for the enzymatic reaction. The xerogel was also subjected to film formation and re‐hydrogelation with appropriate techniques. magnified image

This article describes preparation of polysaccharide–polymethacrylate hybrid materials by means of free‐radical polymerization of a cationic methacrylate monomer in the presence of anionic polysaccharides. In particular, synthesis of the hybrid material composed of carboxymethyl cellulose (CMC) and a cationic polymethacrylate, i.e. poly(2‐aminoethyl methacrylate) is disclosed. The formation of the materials was achieved by radical polymerization of 2‐aminoethyl methacrylate hydrochloride (AEMA‐HCl) in aqueous solution of CMC. The insoluble material was formed and the structure was determined by the IR spectra and elemental analysis to be composed of CMC and polymethacrylate. Thermal analyses such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed to confirm the network structure of the material. The dehydrative amidation occurred by heating the material at 200°C, giving rise to the new hybrid material hybridized by the amide linkages. Copyright © 2007 John Wiley & Sons, Ltd.

An amylose‐grafted chitosan has been synthesized by a chemoenzymatic method according to the following two reactions. First, maltoheptaose is introduced to chitosan by a reductive amination using sodium cyanotrihydroborate in a mixed solvent of 1.0 mol · L⁻¹ aqueous acetic acid and methanol at room temperature to produce a maltoheptaose‐grafted chitosan that has a well‐defined molecular structure. A phosphorylase‐catalyzed enzymatic polymerization of α‐D‐glucose 1‐phosphate is then performed from the maltoheptaose‐grafted chitosan to obtain the amylose‐grafted chitosan. This material does not dissolve in any solvent, e.g., aqueous acetic acid and dimethyl sufoxide, which are good solvents for chitosan and amylose, respectively. magnified image

In this article we describe a new method of polymerization called “vine‐twining polymerization” for preparation of well‐defined supramolecules, which are amylose–polymer inclusion complexes. The method was achieved by enzymatic polymerization of α‐D‐glucose‐1‐phosphate catalyzed by phosphorylase in the presence of various synthetic polymers such as polyethers, polyesters, poly(ester–ether), and amphiphilic block copolymer. Powder X‐ray diffraction (XRD) and ¹H‐NMR measurements determined the structures of the products to be inclusion complexes. The XRD patterns were completely different from those of amylose and guest polymers. The ¹H‐NMR spectra of the products indicated that the structures were composed of amylose and guest polymers. The formation process of the inclusion complexes during the enzymatic polymerization was also evaluated. In addition, we revealed that the bulkiness of the end groups and the hydrophobicity of the guest polymers strongly affected the formation of the inclusion complexes. By means of this method of polymerization, a graft polymer having inclusion complexes as side chains was prepared. Furthermore, as an evolution of the “vine‐twining polymerization,” we attempted a system of parallel polymerization to form an inclusion complex of amylose with a strongly hydrophobic guest polymer. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 36–46; 2005: Published online in Wiley InterScience ( www.interscience.wiley.com) DOI 10.1002/tcr.20031