Construction Of Self-healing Hydrogel With Diselenide Bond

Hydrogels are soft materials with cross-linked three-dimensional fiber networks formed by physical or chemical action.It is characterized by high water content,microporous structure,adjustable mechanical stability and good biocompatibility.Therefore,hydrogel has attracted much attention in the field of regenerative medicine and drug delivery.However,not only limited use of hydrogel material by the original mechanical strength but also it needs to meet the specific needs of different aims.Hydrogels are endowed with self-healing behavior and a variety of response behaviors through reasonable design.Supramolecular interactions and dynamic covalent bonds are stimulus responsive.They are ideal driving forces for the construction of intelligent hydrogels,which compared with the traditional hydrogel has the possibility to realize intelligence.With the help of diselenide bond,we prepared self-healing protein hydrogel.At the same time,we conducted studies on the enhancement of the hydrogels’ mechanical properties and degradation of hydrogels,and obtained the following results:1.Construction of light-responsive self-healing protein hydrogel containing diselenide bondsDisulfide bond is a common dynamic covalent bond in life,which has been widely studied.At the same time,diselenide bond energy is lower than disulfide bond energy,and the dynamic exchange can take place under visible light.The self-healing materials containing diselenide bonds,which are reported,are mostly made by incorporating diselenide bonds into polyurethane(PU)elastomers.There is a lack of relevant reports on other kinds of materials.In this paper,we prepared a light-responsive self-healing protein hydrogel based on diselenide bond.In the process of constructing the hydrogel with BSA protein and glutaraldehyde,we added diselenide to make the skeleton of the hydrogel network contain the part that responds to light.Through this strategy,BSA protein hydrogel is endowed with the ability to repair under visible light irradiation.The influencing factors of repair are further explored,and it is found that there are optimal values of protein content and diselenide content for repair.The hydrogel with protein content of 14.4 wt% and diselenide content of 0.8 wt% can achieve 100% selfhealing efficiency by illumination of 16 h.It is found that the repair behavior of hydrogel has two typical types,corresponding to two repair modes: dynamic covalent bond regeneration and chain diffusion.2.Regulation of strength of protein hydrogel containing diselenide bondsThe dynamic exchange of diselenide bonds make the polymer network of hydrogel rearrange under visible photo-irradiation.Thus,the homogenization of network improves the stiffness of hydrogel.Here,by introducing diselenide bond into protein hydrogel,the modulus of the diselenide-containing protein hydrogel was greatly enhanced after illumination for 16 h.And the Young’s modulus increased from 0.015 MPa to 0.078 MPa.The SEM contrast of diselenide-containing hydrogel before and after illumination clearly indicated the change of the hydrogel tissue after illumination,which fully proved that the gel network was homogenized.Applications of hydrogels in biomedicine often need to take into account the biodegradable properties.The structure of the diselenide-polymer can be destroyed in many ways.Here,we prepared a multi-stimulus responsive degradable hydrogel,which can react with hydrogen peroxide generated during the catalytic oxidation of glucose and responds to a high concentration of diselenide solution.By adding glucose oxidase(GOx)into the hydrogel,the hydrogels can be completely dissolved in 0.2 M glucose solution within48 hours.The hydrogel can be degraded in 30 minutes with a small amount of 10 wt%selenocysteine solution added to the surface of the hydrogel.