| Joint disease is one of the main diseases that affect people's health.There are nearly 40 million patients suffering from joint disease in our country.Since the structure and function of articular cartilage and subchondral bone are closely related,joint disease usually leads to the simultaneous lesion of them.The integrative repair of articular cartilage and subchondral bone provides a new way for the treatment of joint diseases.Polyvinyl alcohol(PVA)hydrogels,are ideal materials for integrative repair for their high water content,strong toughness,flexibility and good biocompatibility.However,there are still many problems in pure PVA hydrogels,such as low mechanical strength,poor biological activity,difficult degradation and poor performance in combination with articular cartilage and subchondral bone.Especially the poor performance in combination with subchondral bone usually cause unconspicuous repair effect.?-Tricalcium phosphate(?-TCP),with good compatibility,biocompatibility and biodegradability,can efficiently solve these problems by incorporated into PVA hydrogels.In this paper,In this paper,four kinds of dry processes were designed to prepare ?-TCP powders,and the physical and chemical properties of ?-TCP powders by different processes were studied.The results reveal that the raw materials with small particle size and good dispersion can be processed through nano ball millingt.the purity of the ?-TCP powders prepared by the nano ball milling and ultrasonic stirring process can reach over 97%,and the average particle size of powders is 666 nm,with high pure and uniform particle size.Then the composite hydrogels were prepared by blending PVA with ?-TCP powders.?-TCP/PVA composite dense hydrogels for articular cartilage repair were prepared by physical crosslinking process of repeated freezing-thawing.Then the physical and chemical properties of the dense hydrogels were discussed.The results show that the mechanical strength of PVA hydrogels can be improved significantly under the addition of ?-TCP powders.The compression modulus can reach 1.31 MPa when the content of ?-TCP powders is 12.5%.The addition of ?-TCP can affect the water content,swelling rate,swelling ratio and the friction coefficient of dense hydrogels.But these effects can be adjusted by changing the concentration of DMSO solution.When the concentration of DMSO solvent was adjusted to 85%,the physical properties of the dense composite hydrogels are sufficiently enhanced,which has a low friction coefficient below 0.025.?-TCP/PVA composite porous hydrogels for subchondral bone repair,which have large pore size over 200 ?m and connecting aperture size over 50 ?m,were prepared by template method.The results show that the compression modulus of porous composite hydrogels can reach 23.7 KPa,with good outstanding shape recovery.The porous hydrogels has controllable biodegradation.The degradation rate of porous hydrogels can be regulated by adjusting the content of ?-TCP and pore size,and the maximum weight loss rate of porous hydrogels with 14 days in vitro can reach 15%.?-TCP/PVA bilayered hydrogels,which have high bonding strength between the dense layer and porous layer,were prepared by repeated freezing-thawing and template method in this paper.The results indicate that the dense layer and porous layer are not easy to crack.The compression modulus of bilayered hydrogels can reach 790 KPa,with high mechanical strength.Moreover,bilayered hydrogels are no toxicity to cartilage cells and synovium mesenchymal stem cells,that is,they have excellent cell compatibility. |
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