Preparation Of Sericin Double Network Hydrogel And Its Application In Cartilage Damage Repair

The articular cartilage lacks blood vessels,lymphatic vessels and nerve distribution,so it is difficult to repair and regenerate the cartilage tissue after damage.The current technical methods used for cartilage damage repair cannot fully meet the clinical needs.With the continuous improvement of tissue engineering and cell therapy technology,research and preparation of cartilage scaffold materials with good repair properties have become a research hotspot.Hydrogels have three-dimensional network structure,strong hydrophilicity,and certain viscoelasticity.Hydrogel is a good material for imitating chondrocyte extracellular matrix.Existing traditional hydrogels cannot provide enough space for rapid cell growth and material exchange due to the dense internal cross-linked structure,and there is a problem of uncontrollable degradation rate.Therefore,this subject intends to prepare a silk with a porous structure.Gelatin double network hydrogel,characterization and analysis of the physical properties of sericin double network hydrogel,the effect of repairing rabbit knee joint cartilage defects in situ and the biological performance of the in vivo environment.The ratio of the materials based on sodium alginate hydrogel was optimized by orthogonal experiments,and the sericin double-network hydrogel was prepared by the method of blending modification.The morphological characteristics of the stent material were characterized by field emission scanning electron microscopy,and the structural characteristics of the stent material were characterized by Fourier infrared scanning.The physical properties of the scaffold material were characterized by testing the mechanical properties,porosity,swelling rate,and water content.The in situ cartilage defect repair experiment of rabbit knee joint was used to evaluate the ability of scaffold materials to induce regeneration and repair of cartilage injury in situ.The scaffold materials were evaluated for cell compatibility,blood compatibility and histocompatibility respectively,to study the influence of different sericin content on the growth of chondrocytes,the interaction with direct contact with blood,and the regulation of inflammation in surrounding tissues.The effect on the degradation rate in the body.The experimental results show that the best process for sodium alginate hydrogel substrate is:SA（2wt%）,CaCO₃（0.5wt%）,GDL（2.5wt%）.After the sodium alginate hydrogel is blended and modified by sericin,the sericin double network hydrogel has hydrogen bonding,and the porosity and pore diameter gradually decrease with the increase of sericin content,and the pore wall The roughness increases and the mechanical properties have been significantly improved.When the sericin content is 1%（m/v）,the compressive strength is the largest,245.17±6.658 Kpa.The content of sericin increases,the hydrophilicity of the material increases,and the swelling rate increases.It reaches a dynamic equilibrium at about 24 hours,and the water content is between85%and 88%at this time.After 4 weeks of implantation of the sericin double network hydrogel in the rabbit knee joint full-thickness cartilage defect,the regenerated tissue and the surrounding natural cartilage tissue are highly integrated,cartilage lacunae are formed,glycosaminoglycans and type II collagen are deposited and the distribution is uniform,and part of the tidal line structure is formed in the regenerated tissue.The sericin double network hydrogel can significantly increase the adhesion rate of chondrocytes,promote the proliferation of chondrocytes,maintain the phenotype of chondrocytes,significantly reduce the rate of hemolysis and platelet consumption,and increase the anticoagulant index.In addition,the sericin double network hydrogel can significantly reduce the infiltration of inflammatory cells,and the degradation controllability of the scaffold material can be achieved by adjusting the content of sericin.In summary,a sericin double-network hydrogel scaffold material developed in this subject has a certain pore structure,degradability,and good biocompatibility.The biological activity of sericin can effectively promote the secretion of type II collagen and glycosaminoglycan in the extracellular matrix of the cartilage further realizes the repair effect on cartilage damage.Sericin double network hydrogel provides a new idea for the preparation of scaffold materials for cartilage tissue engineering,and has broad prospects in future clinical applications.