Application Of Hydrotalcite Nanoparticles Loaded With Selenium Nanoparticles In The Treatment Of Osteosarcoma And Bone Tissue Regeneration

Osteosarcoma has a high degree of malignancy and can pose a significant threat to the lives and health of patients.Currently,clinical treatment methods,such as surgical resection,radiotherapy,chemotherapy,etc.,have limitations such as damage to normal bone tissue and difficulty in eradication.Therefore,it is necessary to develop new treatment methods for osteosarcoma.Chemodynamic therapy（CDT）,which uses reactive oxygen species generated by the Fenton reaction activated by the tumor microenvironment（TME）to kill tumor cells,has received widespread attention from researchers.However,its therapeutic efficacy is limited by factors such as low levels of H₂O₂in tumors and high levels of glutathione（GSH）.Selenium nanoparticles（Se NPs）can promote the generation of superoxide anion free radicals(O₂^·-)in organisms,increase the activity of superoxide dismutase（SOD）,catalyze the conversion of O₂^·-into H₂O₂,and increase the level of H₂O₂in tumors,thereby improving the efficacy of CDT.However,Se NPs have poor stability,are prone to aggregation and loss of biological activity.In addition,osteosarcoma significantly invades normal bone tissue,and the treatment of osteosarcoma can also produce bone defects that exceed the critical bone defect threshold and are difficult to heal themselves.Therefore,it is necessary to study new materials combined with carriers and Se NPs,so that they can not only enhance the therapeutic effect of CDT on osteosarcoma,but also achieve bone tissue regeneration at bone defect sites.Layered double hydroxides（LDHs）have been proven to be a good carrier,and bioactive glass（BG）is also a tissue engineering biomaterial that can be used to prepare composite scaffolds.In this paper,selenium nanoparticles were loaded on the surface of Mg Fe-LDH nanosheets by in-situ reduction method,and hydrotalcite nanocomposites（LDH/Se）loaded with selenium nanoparticles were prepared.After that,they were coated on bioactive glass by immersion method to explore their application in bone tissue engineering.Mg²⁺in LDHs laminates plays a key role in osteogenesis and differentiation.Both Fe³⁺and Fe²⁺produced by glutathione reduction can react with H₂O₂to achieve chemodynamic treatment of tumor microenvironment response and bone tissue regeneration at the defect site.The positively charged main laminate of LDHs can be used to stabilize negatively charged Se NPs,improve their stability,and improve the problem of insufficient H₂O₂levels in the tumor microenvironment.The specific research content and results are as follows:1.Preparation and performance study of LDH/Se nanosheetsFirstly,Mg Fe-LDH nanosheets were synthesized by a"bottom-up method".After that,successively drip Na₂Se O₃and L-cysteine solutions dissolved in deionized water,and through the principle of electrostatic adsorption,in-situ reduce Se O₃^2-on LDHs laminates to obtain LDH/Se nanosheets.The SEM photos,zeta potential,and hydration particle size characterization of the material showed that Se NPs were successfully loaded onto LDHs laminates,with uniform particle size,and good dispersionand significantly improved stability.The Fenton reaction properties of the composite were verified by UV-vis spectroscopy,fluorescence spectroscopy,and electron spin resonance（ESR）methods.Due to the presence of Fe³⁺,composite materials have a significant consumption capacity for GSH,and can catalyze the production of highly toxic·OH from H₂O₂through the Fenton reaction pathway under weakly acidic conditions.The reaction kinetics of the formation of·OH was tested using 3,3’,5,5’-tetramethylbenzidine（TMB）,and the Michaelis constant K_m=0.61 m M was obtained using M-M equation fitting,the maximum reaction rate V_max=2.05×10^-8M s^-1.In addition,LDH/Se has an ionic slow-release property,which can control the release of Mg²⁺and Fe³⁺that promote osteogenic differentiation,helping to promote osteogenic differentiation.2.Study on the treatment of osteosarcoma and bone tissue regeneration performance of LDH/Se nanotabletsWe validated the potential application of LDH/Se in the treatment of osteosarcoma and bone tissue regeneration through biological experiments,utilizing its Fenton reaction performance and ion release performance.First,we studied the biocompatibility of LDH/Se composite materials on MG63cells,and verified the ROS production ability and CDT effect of LDH/Se nano materials in tumor microenvironment response at the cellular level.Secondly,we immersed LDH/Se on the surface of BG to validate the tumor ablation effect of LDH/Se on tumor bearing mice,as well as its biological safety and metabolism in vivo through in vivo experiments.Finally,we explored the ability of LDH/Se to promote osteogenic differentiation of BMSCs and promote the healing of rabbit skull defects at both the cellular and in vivo levels.In addition,the Fenton reaction performance of LDH/Se can be utilized to achieve tissue engineering antibacterial activity.In summary,this thesis has prepared LDH/Se nanomaterials with dual functions of osteosarcoma treatment and bone defect repair by utilizing the adjustable variability,high specific surface area,and laminate electronegativity of LDHs.The introduction of Se NPs has improved the therapeutic effect of CDT,providing ideas for the exploration of new therapeutic methods for osteosarcoma and the development of therapeutic-regenerative dual functional materials.