Sustained heparin release actuator achieved from thermal and water activated shape memory hydrogels containing main-chain LC units

In this work, liquid crystalline (LC) monomer with two n-decenoyl terminated groups was synthesized and applied into shape memory hydrogels containing main-chain LC unit by Michael addition polymerization. The liquid crystalline textures of LC monomer and hydrogels were determined by polarized optical microscopy. Thermal and water activated shape memory properties were investigated. And the shape memory properties were improved by incorporating main chain LC unit into hydrogels. The biocompatibility was evaluated by the cytotoxicity test and all these hydrogels illustrated no cytotoxicity. The good biocompatibility and reinforced shape memory properties with shape fixity ratio higher than 96% and shape recovery ratio higher than 93%, indicating a new idea to prepare shape memory hydrogels by introducing main-chain mesogenic units into hydrogels in the safe application of smart biomedical areas. Finally, water-activated actuators were prepared and could change themselves into C or S shape in water at 25 degrees C with about 20 min. And through in vitro heparin release of hydrogel and actuator investigation, more sustained heparin release performance of actuator was observed in our study. This indicated that the heparin loaded actuator would have potential application in anticoagulant scaffold by combining the sustained heparin delivery character and the shape self-changing character of water-activated actuators.