Preparation And Properties Of Tough And Adhesive Protein Hydrogel

Hydrogel has received much more attention because of high water content and excellent biocompatibility.Adhesiveness is a unique property for materials with high water content,and this property allows hydrogel used in many fields,such as wearable equipment,biological glue and medical bandages.However,the adhesive hydrogel obtained at this stage usually have low mechanical strength,so it is very important to fabricated a hydrogel with high mechanical properties,excellent adhesion and good biocompatibility.In this paper,a tough and adheisve protein hydroegl driven by milk protein was fabricated.Casein was introduced into polyacrylamide hydroegl,the protein network formed by the physical interaction between the casein can form a hybrid network with the polyacrylamide network to improve the mechanical properties of the hydrogel.Moreover,functional groups in protein molecules can produce intermolecular interactions with different materials and thus have adheison properties.The fracture stress and strain of caseinpolyacrylamide hydrogel were180 k Pa and over 2000%,respectively.The maximum peeling force on the surface of aluminium was 378 N/m.Moreover,the hydrogel can be peeled repeatedly through potential physical interactions,and can be bonded to various solid materials and biological tissue surfaces.In order to further improve the mechanical strength of the hydrogel,and to make the hydrogel have adhension adjustability.The hydrophobic monomer MEA was introduced into the system.Hydrophobic interaction can be combined with the hydrophobic part of milk protein as a physical crosslinking center.It can effectively dissipate energy and improve mechanical properties.The fracture stress was 258 k Pa and fracture strain was 2200%.In addition,the adhesion between the hydrogel and the different materials can be adjusted by adjusting the ratio of the hydrophobic monomer MEA to sodium caseinate.The hydrogel can achieve repeated peeling tests over 40 times on the hydrophobic rubber material,and the hydrogel was bonded between the rubber sheets without separation by multiple torsion experiments.This thickening strategy through protein biomolecules not only provides a new design method for the preparation of tough and adhesive hydrogels,but also expands the application of hydrogels in bioelectrodes,wearable devices,gel electrolytes.