| Background and objective:The repair of bone defects is a matter of great concern in the medical field,as bone defects may lead to pain and inflammation that impair patients’well-being.The causes of bone defects vary,such as trauma,tumor,infection,congenital malformation,etc.Currently,the main approaches for repairing bone defects are autologous bone graft,allogeneic bone graft,and synthetic material graft.However,each of these procedures carries its complications and drawbacks.Therefore,finding a new method that can effectively,safely,and economically repair bone defects is a pressing concern in the medical field.In this regard,aerogel shows great potential for application as a scaffold material with special properties such as high surface area,low density(0.003-0.5g/cm-3),and high porosity（80%-99.9%）.Aerogel exhibits excellent biocompatibility and high porosity similar to human bone cancellous structure,and by adjusting its porosity,it can have mechanical properties matching with bone tissue.However,the osteogenic effect is still inadequate when simply using scaffold materials to repair bone defects.Non-invasive physicomechanical interventions can accelerate the healing of bone defects by providing appropriate mechanical signals or energy stimulation to promote osteoblast proliferation,differentiation,and gene expression.Combining physical factor stimulation with bone defect repairing materials is one of the strategies to optimize bone defect treatment,which can achieve synergy between physical factor stimulation and bioactive scaffold materials,thus improving the efficiency and quality of bone defect repair.Silicon dioxide（Si O2）and hydroxyapatite（HAP）are both bioactive ceramic materials that can promote the osteogenic differentiation of stem cells and mineralization of bone matrix by elevating the concentration of inorganic ions such as silica,calcium,and phosphorus ions in the osteogenic microenvironment.However,disadvantages such as lack of cell adhesion and growth severely limit the therapeutic effects of these bio-ceramic materials.Polydopamine（PDA）is a biopolymer resulting from the polymerization of dopamine monomers.PDA can form a uniform and stable coating on the surface of numerous materials,providing good cell adhesion and biocompatibility.Polydopamine-modified materials can mimic the extracellular matrix（ECM）and provide an environment for cell support,attachment,and signaling,thereby improving cell behavior and function on the material surface.In this study,we will prepare high-porosity bioactive aerogels based on PDA-modified Si O2-HAP nanofibers,and investigate using in vitro and in vivo experiments whether LIPUS combined with aerogel could achieve a synergistic effect in promoting bone regeneration.Methods:1.First,silicon dioxide-hydroxyapatite nanofibers（Si O2-HAP）were pre-prepared by electro-spinning technique,and the surface of the fibers was modified with polydopamine（PDA）after the fiber was fragmented using a homogenizer,and then the PDA@Si O2-HAP fiber segments were dispersed in aqueous silica sol solution.The porous bioactive nanofiber aerogels（AG）were prepared by the freeze-drying method.2.The surface morphology,network structure,composition,and compressive strength of bioactive aerogel were characterized using scanning electron microscopy,Fourier infrared spectroscopy,X-ray diffraction,and a universal testing machine.3.CCK-8 assay,cell live-dead staining assay,cytoskeleton staining assay,quantitative alkaline phosphatase assay,immunofluorescence staining assay,and real-time fluorescent quantitative PCR were used to evaluate the effect of aerogel combined with LIPUS on the adhesion,proliferation,and differentiation of rat bone marrow mesenchymal stem cells（r BMSCs）.4.To establish a critical bone defect in the skull of rats and evaluate the effect of aerogel combined with LIPUS in treating bone defects.Results:In this study,Si O2-HAP nanofibers and PDA@Si O2-HAP aerogels with suitable compressive strength and high porosity were successfully prepared for bone regeneration research.In vitro,experimental results show that LIPUS can further activate the adhesion,proliferation,and differentiation ability of cells grown on PDA@Si O2-HA aerogels.The results of clinical bone defect repair in rats showed that the combined application of LIPUS and AG had a good synergistic effect on the formation of new bone.Therefore,this study concluded that the combination of high porosity bioactive aerogel and LIPUS is one of the effective therapeutic measures to accelerate bone regeneration. |
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