Abstract
SynopsisNetwork polymers of poly(acrylic acid) cross-linked with elastin-like peptide(PAA-ELP(n%), n% : degree of crosslinking) were newly designed and synthesized to fabricate dual-responsive polymer materials. The polymerizable ELP as a cross-linker, which contains methacrylamide group at both chain ends, was first prepared by solid-phase synthesis using Fmoc chemistry, and then two types of network polymers(PAA-ELP(1%) and (2%)) were successfully obtained by radical copolymerization of this ELP and acrylic acid. Temperature－dependent structural and assembling properties of these polymers in water were examined by using CD and turbidity measurements. PAA-ELP(1%) showed a phase transition with upper critical solution temperature, based on the conformational change of the ELP segment from random coil to ordered structure involving type II β-turns along with the temperature rise. On the other hand, PAA-ELP(2%) was found to form hydrogel and to give a marked temperature－dependence of the swelling ratio at neutral pH region close to the pKa of PAA segment. This hydrogel was also found to transform gradually to a sol state by cleaving peptide bonds of the ELP segment with papain as a peptide segment cleavable enzyme.(Received August 10, 2010)
