Preparation and characterizations of all-biodegradable supramolecular hydrogels through formation of inclusion complexes of amylose

In this study, we found that the hydrogel containing cross-linking points of amylose/PCL graft chain inclusion complexes was obtained by vine-twining polymerization using a water-soluble chitosan-graft-poly(ε-caprolactone) (chitosan-g-PCL). When phosphorylase-catalyzed enzymatic polymerization was performed in the presence of chitosan-g-PCL, the reaction mixture turned into a gel form. The IR spectrum of the sample obtained by lyophilization of the hydrogel indicated that amylose included the PCL graft chains in the intermolecular (chitosan-g-PCL)s to produce cross-linking points. The evaluation of the hydrogels obtained under various conditions was conducted by the shear-viscosity measurement. Because amylose, chitosan, and PCL are known to be enzymatically hydrolyzed, we have investigated enzymatic disruption behaviors of the hydrogels by hydrolysis of these components catalyzed by the corresponding enzymes, i.e., β-amylase, chitosanase, and lipase, respectively. In all cases, the hydrogels were transformed into solution or suspension states, indicating the occurrence of enzymatic disruption of hydrogels. Furthermore, the hydrogel was reproduced when the vine-twining polymerization was carried out in the presence of phosphorylase in the resulting solution by the β-amylase treatment.