A covalently crosslinked silk fibroin hydrogel using enzymatic oxidation and chemoenzymatically synthesized copolypeptide crosslinkers consisting of a GPG tripeptide motif and tyrosine: control of gelation and resilience

Abstract

A covalently crosslinked silk fibroin hydrogel (ChemSF) was successfully formed via an enzymatic crosslinking reaction using chemoenzymatically synthesized copolypeptides [poly(GPG_n-r-Y_m)], which consist of a glycine–proline–glycine (GPG) tripeptide motif and tyrosine (Y), as linker molecules. The gelation time of ChemSF was effectively shortened to less than 100 seconds without loss of toughness by adding poly(GPG_n-r-Y_m). In addition, the resilience of ChemSF was improved up to 86% at 66% strain, comparable to that of elastin, due to the flexible conformation of the poly(GPG_n-r-Y_m) crosslinker. The acceleration of the gelation and the improvement of the resilience of ChemSF were simultaneously achieved by using a multifunctional peptide crosslinker.