Universal Strategy for Designing ShapeMemory Hydrogels

Smart polymeric biomaterials have been the focusof many recent biomedical studies, especially those withadaptability to defects and potential to be implanted in thehuman body. Herein we report a versatile and straightforwardmethod to convert non-thermoresponsive hydrogels intothermoresponsive systems with shape memory ability. As aproof of concept, a thermoresponsive polyurethane mesh wasembedded within a methacrylated chitosan (CHTMA), gelatin(GELMA), laminarin (LAMMA) or hyaluronic acid (HAMA)hydrogel network, which afforded hydrogel composites withshape memory ability. With this system, we achieved good toexcellent shapefixity ratios (50-90%) and excellent shaperecovery ratios (similar to 100%, almost instantaneously) at bodytemperature (37 degrees C). Cytocompatibility tests demonstrated good viability either with cells on top or encapsulated duringall shape memory processes. This straightforward approach opens a broad range of possibilities to convey shape memoryproperties to virtually any synthetic or natural-based hydrogel for several biological and nonbiological applications.