Radiation Construction Of PVA/PMPC-CaCl₂ (PP-Ca) Double Network Hydrogel And Its Cartilage Repair Behavio

Due to the increasingly serious aging society,osteoarthritis and other articular cartilage diseases have become one of the increasing burdens of public health,and the complex structure of articular cartilage and the lack of blood vessels and nerves,the repair of cartilage damage has been a challenging problem.There is an urgent need to propose a safe and convenient solution to cartilage repair.Using PVA,PMPC and CaCl₂as the raw materials of double-network hydrogel,the initial network structure of PVA hydrogel was prepared through the cyclic freeze-thawing process,and the structure was soaked into the second layer network containing PMPC-CaCl₂monomer.The second network monomer penetrates into the first layer network structure of the hydrogel,and the obtained samples are crosslinked by radiation as the second layer network structure of the hydrogel to obtain PP-Ca DN hydrogel.The effect of the total absorbed dose on the degree of crosslinking of hydrogels was discussed with the absorbed dose rate of 5 kGy/pass and the total absorbed dose of 5-30 kGy.The gel fraction showed that when the total absorbed dose was 20 kGy,and the gel fraction could reach 89%.The swelling rate of irradiated hydrogels was compared with that of ternary hydrogels.The results showed that the swelling rate of ternary hydrogels was much higher than that of single and binary hydrogels,reaching 554%.A universal testing machine was used to test the mechanical properties of hydrogels.The results showed that the tensile and compression modulus of the three-component hydrogels were greater than that of the one-component and two-component hydrogels,the tensile modulus could reach 2.3MPa,the compression modulus was 0.17MPa,and the maximum strain could reach 275%.The excellent mechanical properties laid a foundation for cartilage repair.The morphology and structure of PP-Ca DN hydrogels were analyzed by infrared（IR）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）and X-ray photoelectron spectroscopy（XPS）.The results showed that PP-Ca DN hydrogels were successfully synthesized.In addition,the antibacterial properties and cytotoxicity of hydrogel were tested,and the results showed that it had significant effects on Escherichia coli and Staphylococcus aureus.The cytotoxicity results showed that PP-Ca DN hydrogel had promoting effects on mouse embryonic osteoblast MC3T3-E1.After osteogenic induction by alkaline phosphatase ALP staining,the results showed that PP-Ca DN hydrogels had a better effect on osteoblast differentiation than the control,unary and binary hydrogels.In vivo osteogenic experiment was conducted in New Zealand white rabbits,and the results showed that PP-Ca DN hydrogel had a better effect on osteoblast differentiation than the control group.The results of 4W and 8W experiments on rabbit cartilage defect repair showed that compared with the experimental model group without hydrogel filling,the experimental group with hydrogel filling had better recovery.In this paper,the cross-linking technique of electron accelerator irradiation was used to prepare strong double network hydrogel for cartilage repair.Compared with the traditional preparation methods of hydrogel antibacterial materials,radiation method has obvious advantages over physical and chemical crosslinking,especially without adding chemical cross-linking,easy operation,normal temperature and pressure,cheap raw materials and environmental protection,and can be applied to industrial production.Based on this unique preparation method and excellent dual-network hydrogel properties,it is expected to be applied in cartilage repair neighborhood.