Enzymatic Preparation of Supramolecular Networks Composed of Amylosic Inclusion Complexes with Grafted Guest Polymers

In this study, we attempted to prepare supramolecular networks composed of amylosic inclusion complexes with grafted guest polymers by means of phosphorylase-catalyzed enzymatic polymerization of α-d-glucose 1-phosphate as a monomer from a maltooligosaccharide primer. When the enzymatic polymerization was examined in the presence of poly(γ-glutamic acid-graft-tetrahydrofuran) (PGA-g-PTHF), the reaction mixture totally turned into a hydrogel form. The powder X-ray diffraction measurement of a lyophilized sample of the hydrogel suggested that enzymatically elongated amyloses formed inclusion complexes with the PTHF graft chains among the PGA main-chains according to vine-twining polymerization manner to construct the supramolecular network structure. Therefore, the product formed the hydrogel with inclusion complex cross-linking as the enzymatic polymerization progressed. The vine-twining polymerization is the method for the formation of amylose-polymer inclusion complexes in the phosphorylase-catalyzed enzymatic polymerization field, which has been previously developed by us. On the other hand, the enzymatic polymerization mixture in the presence of poly(γ-glutamic acid-graft-l-lactic acid) (PGA-g-PLLA) did not induce the hydrogel formation upon the same operation. In this system, enzymatically elongated amyloses did not form inclusion complexes with the PLLA graft chains due to their bulkiness, but sorely constructed well-known double helical assemblies, resulting in their aggregation in the reaction mixture.