Preparation Of Modified 45S5 Bioactive Glass And Study Of Its Osteogenic And Antibacterial Properties

Background: Bioactive glass is a synthetic silica-based material whose excellent bioactivity,osteoinductive and antibacterial properties make it a highly sought-after bone replacement material.Among them,45S5 bioglass(with Si O2-Ca O-Na2O-P2O5 as the main component)has been widely used.Its bioactivity is demonstrated by the release of large amounts of calcium and phosphorus ions and deposition of hydroxyapatite on the surface of the material upon contact with water or body fluids,which further binds to bone tissue.In addition,dissolution products of bioactive glasses and related glass-ceramics play a specific role in osteogenesis and angiogenesis.The addition of specific elements such as dopants magnesium,strontium,zinc,fluorine,copper and boron can modulate the biological properties of bone replacement materials.In order to further improve the biocompatibility of bioactive glasses,promote the expression of relevant osteogenic genes,enhance their antimicrobial properties,and promote bone defect repair,this thesis selectively added strontium oxide and magnesium oxide as dopants and successfully prepared bioactive glasses with amorphous structure.Through the addition of dopants,the biological properties of bone replacement materials were modulated,providing a favorable reference for the treatment of bone defects and bone infections.Objective: In this study,a new bioactive glass(Bioactive Glass Magnesium Strontium Nanoparticle,BGMSN)was prepared by melting method by introducing strontium oxide and magnesium oxide into the classical 45S5 bioactive glass and evaluated for its bioactivity,biocompatibility,in vitro and in vivo induced osteogenesis and antibacterial properties.Methods:1.Strontium oxide and magnesium oxide were introduced into the classical 45S5 bioglass by the melt-quenching method.The structural and surface properties of the new bioactive glasses were evaluated by scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier infrared spectroscopy(FTIR),and water contact angle tests.2.In vitro experiments:(1)human simulated body fluid(SBF)to determine the bioactivity of BGMSN;(2)cellular and molecular biology experiments: CCK-8 cell proliferation assay to study the biocompatibility of BGMSN;mouse embryonic osteoblasts(MC3T3-E1)inoculated onto bioactive glass and calcium xanthophyll staining to verify cell adhesion;reverse transcription-polymerase chain reaction(RTPCR)to study the expression of osteogenic genes.3.Antibacterial experiments: BGMSN bioactive glass and classical 45S5 bioactive glass were co-cultured with aerobic bacteria(Staphylococcus aureus;Escherichia coli)and parthenogenic anaerobic bacteria(Streptococcus pyogenes)respectively,and their antibacterial performance was evaluated by plate count method.4.Animal experiments: SD rats with 5-mm diameter cranial defects were established and implanted with BGMSN and 45S5 bioactive glass,respectively.The rats were executed at 4 and 8 weeks,and the cranial bone samples were removed and analyzed by Micro-CT,HE staining,Masson staining and immunohistochemistry for their effects on angiogenesis and bone formation.Results:1.By melt-quenching method,XRD results showed that the bioactive glass BGMSN with non-crystalline structure was successfully prepared.FTIR detected the characteristic peaks of bioactive glass: hydroxyl and phosphate,and water contact angle test results proved that BGMSN bioactive glass has good hydrophilicity.2.In vitro experiments: SBF test initially proved the bioactivity of BGMSN,and the results of cellular and molecular biology experiments showed that both bioglasses have good biocompatibility,but BGMSN is more favorable to cell proliferation and higher expression of bone formation-related genes ALP compared to 45S5 bioactive glass.3.Antibacterial test: Plate count method shows that BGMSN has more excellent antibacterial performance compared to 45S5 bioactive glass for both aerobic bacteria and parthenogenic anaerobic bacteria.4.Animal experiment: Micro-CT,histological and immunohistochemical analysis showed that BGMSN bioactive glass formed more mature bone collagen fibers and higher expression of bone formation-related genes ALP,BMP-2,and OPN compared with 45S5 bioactive glass.Conclusion: A new bioactive glass BGMSN with non-crystalline structure and excelent biological properties was successfully prepared by melting-quenching method,which is more conducive to cell proliferation and adhesion,exhibits good osteogenic properties,and has excellent antibacterial properties against bacteria,providing a novel strategy for the repair and reconstruction of clinical bone defects.