Functional Protein Hydrogels with Self-Healing Capacity for Biomedical Applications

Self-healing, a property of autonomically triggered recovery after damage, is one of the most outstanding properties observed in biological materials. Among various strategies for self-healing materials, intrinsic system which use inherent reversibility of physiological interactions or chemical bonds attracted most attention. Smart materials, which possess the property of rapid response to environmental changes, provide an approach to self-healing materials due to their biomimicking functions. Herein, this dissertation aims at design and synthesizing intrinsic self-healing protein hydrogels with different functionalities. Firstly, we present herein a strategy for construction of self-healing protein hydrogels with thermal method. Repeated self-healing events with about 100% recovery extent was observed. However, external thermal requirement to trigger the self-healing mechanism in this system prevents its application in biomedical area. Then, a new class of protein hydrogel system was developed at room temperature under physiological pH based on cooperation of ion-mediated protein-protein interaction and bridging effect. Excellent self-healing properties of this hydrogel system were observed without external stimuli at room temperature under physiological pH, and this behavior can be promoted with the presence of divalent ions in physiological concentration. In addition, superior biocompatibility has been demonstrated by in vitrocytotoxicity analysis, suggesting potential biomedical application of this material in drug delivery, biological repair and tissue engineering. In order to improve healing efficiency and broaden the scope of applications of self-repairing protein hydrogels, a third system was brought. The protein hydrogels were fabricated by adjusting pH of the protein solutions. Rapid recovery as well as stronger healing capability were observed and quantitatively studied. In addition, this hydrogel exhibits self-adhesion and autofluorescence, which expand its application to where versatility of material is required under abrasive condition. Stimulus-responsive repairing to original state of mechanical properties in intrinsic self-healing protein hydrogels were demonstrated. The easy preparation and modification of the hydrogels opens an avenue in design of self-repairing materials with other desired functionalities.