Abstract
Self-healing is a capacity observed in most biological systems in which the healing processes are autonomously triggered after the damage. Inspired by this natural behavior, researchers believed that a synthetic material possessing similar self-recovery capability could also be developed. Albeit various intrinsic self-healing systems have been developed over the past few decades, restriction on the biocompatibility due to the required synthetic conditions under extreme pH and with poisonous cross-linker significantly limits their application in biomedical field. In this study, a highly biocompatible nanocomposite protein hydrogel with excellent biomimetic self-healing property is presented. The self-healing protein gel is made by inducing calcium ions into the mixture of heat-induced BSA nano-aggregates and pristine BSA molecules at room temperature and under physiological pH due to the ion-mediated protein-protein association and the bridging effect of divalent Ca2+ ions. The as-prepared protein hydrogel shows excellent repetitive self-healing properties without using any external stimuli at ambient condition. Such outstanding self-recovery performance was quantitatively evaluated/validated by both dynamic and oscillatory rheological analysis. Moreover, with the presence of calcium ions, the self-healing behavior can be significantly facilitated/enhanced. Finally, the superior biocompatibility demonstrated by in vitro cytotoxicity analysis suggests that it is a promising self-healing material well-suited for biomedical applications.
Highlights
Smart materials possessing rapid response to environmental changes have drawn increasing interests due to their unique biomimetic functions[1,2]
For the first time here we report a novel self-healing system based on gelation of the mixture of thermally induced bovine serum albumin (BSA) protein nano-aggregates and fresh BSA molecules upon the addition of metal ions
Requires three steps: first, fibrillar BSA aggregates were obtained after thermally-induced unfolding of the native BSA protein and the as-prepared BSA nano-aggregates solution is transparent and homogenous due to the small size of BSA aggregates; after cooling down to room temperature, further aggregation was achieved by adding fresh native BSA into the solution, in which the mixture remains transparent and homogeneous, and gels were formed by inducing calcium ions into the mixture
Summary
Smart materials possessing rapid response to environmental changes have drawn increasing interests due to their unique biomimetic functions[1,2]. After running out of the limited amounts of healing agents, the self-healing process cannot be repeated in the same area[5,16] Another self-repairing strategy relies on utilizing reversible chemical bonds or physical interactions. Such self-healing system can withstand repetitive damage due to their intrinsic stimuli-responsive self-healing properties. To realize the repetitive biomimetic self-healing system with good biocompatibility at benign biological conditions is still an unmet challenge yet critical for potential biomedical applications To address this challenge, for the first time here we report a novel self-healing system based on gelation of the mixture of thermally induced bovine serum albumin (BSA) protein nano-aggregates and fresh BSA molecules upon the addition of metal ions. The presence of additional calcium ions (even at biological Ca2+ concentration level) could significantly promote and facilitate the self-healing behavior
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