Radiation Construction Of Hot-melt Castable TPU-based Gel And Study Of Its Biological Activit

The degree of aging of our population is becoming more and more serious,and the demand for bone filling material is increasing.Therefore,it is necessary to synthesize a biological bone tissue material with biocompatibility,antibacterial properties,strong hydrophilicity and cell strong adhesion.In this paper,thermoplastic polyurethane(TPU),nano-hydroxyapatite(HAP)and graphene oxide(GO)were used as raw materials of ternary composite gel.The electron beam with a total dose of 20 kGy and a dose rate of 5 kGy/pass was selected and irradiated at room temperature by using melt blending method and electron beam radiation method.A porous thermoplastic polyurethane based gel scaffold was prepared by loading nano-hydroxyapatite particles and GO on the porous polyurethane scaffold,which could be used in bone tissue engineering.The composite gels of TPU/HAP,TPU/HAP/GO were analyzed by infrared analyzer(FTIR)and X-ray diffraction analyzer(XRD).The results showed that TPU,HAP and GO were successfully prepared.Differential scanning calorimetry(DSC)showed that the LCST of composite gel was within the range of 50°-55°,which was quite different from the temperature of human body,which laid a foundation for the application of human body.A universal tension machine was used to test the mechanical properties of the composite gel,and the mechanical properties of the composite gel became stronger after adding GO,which laid a foundation for the application of bone tissue.Scanning electron microscopy(SEM)showed the typical three-dimensional network structure of the composite gel,and Mapping showed the uniform distribution of each element.Specific surface area analysis(BET)proved that adding GO nanoparticles could increase the specific surface area and pore volume.The results of swelling rate and contact angle showed that the composite gel had good hydrophilicity and provided suitable hydration environment for cell adhesion and growth.These structural characterization proved that the composite gel had the best mechanical property when HAP and GO ratio was 20:3 and irradiation dose was 20 kGy.The antibacterial properties and cell activities of the prepared TPU/HAP and TPU/HAP/GO composite gels were investigated by bacterial and cell experiments.Staphylococcus aureus and Escherichia coli were selected for bacteriostatic experiments.Plate counting method showed that the bacteriostatic effect of TPU/HAP/GO gel was stronger than that of TPU/HAP gel.Compared with blank group,both of them had certain antibacterial properties.Mouse osteoblasts(MC3T3-E1)were selected for cytotoxicity,apoptosis and osteogenesis experiments.MTT assay,Hoechst 33342/PI double dyeing method confirmed that the gel did not produce toxicity to MC3T3-E1 cells and had good biocompatibility.ALP staining showed that the gel could promote osteogenic differentiation of MC3T3-E1 cells.The gel has great potential in bone tissue engineering.