Elastin-Based Thermoresponsive Shape-Memory Hydrogels

Abstract

A shape-memory\nhydrogel is a programmable hydrogel material that\ncan store specific shapes and execute functions in response to stimuli.\nIn this report, we developed shape-memory hydrogels by creating double-network\npolymeric structures using a physically cross-linking elastin-like\npolypeptide (ELP) and a chemically cross-linking polyacrylamide (PAM).\nWe synthesized the hydrogel matrix by polymerizing the acrylamide\nmixed in an ELP solution. We exploited the lower critical solution\ntemperature transition of the ELP to enable the hydrogel to hold a\nnew desired shape at an elevated temperature of 55 °C. The original\nshape of the hydrogel can then be recovered by lowering the temperature\nto 20 °C. The shape-memory hydrogels we developed exhibit ultrafast\nfunctionality and high repeatability. Taking advantage of the temperature-induced\nshape-memory capability, we also demonstrate practical functions such\nas gripping an object and connecting two tubes. Our materials with\neffective temperature-driven shape-memory functionality will be useful\nfor developing novel materials for biomedical applications in the\nfuture.