Preparation And Properties Of Photothermal Controlled Bioactive Magnesium Phosphate Bone Cement

Healing of complex bone defects caused by the disease often requires the help of external conditions.Autografts and allografts are limited by issues such as limited sources,immune responses,and potential risks of infection and disease transmission.Currently,widely used bone repair materials in the clinic can only promote bone regeneration in less severe defect sites and do not have the function of treating diseases.The proposed bone tissue engineering（BTE）strategy and four elements of bone tissue engineering point the way for the optimal design of bone repair materials.Relevant studies have shown that in vivo bone regeneration can be achieved through the combined action of internal signals in the scaffold and external physical stimuli,thereby reducing the dependence of bone tissue engineering on pure biological signals such as living cells and growth factors.Photothermal therapy,which eliminates tumor cells and inhibits bacterial growth through thermal ablation technology,has attracted much attention.In this paper,a photothermally controlled bioactive magnesium phosphate cement system（NTMPC）was constructed,and the application of NTMPC in osteogenesis,antibacterial,and tumor growth inhibition was systematically evaluated.The conclusions of this study can provide a theoretical basis for the application of lanthanides in biomaterials and applications in photothermal osteogenesis antibacterial and tumor thermal ablation.The significant studies in this thesis are as follows:（1）Multifunctional calcium-based nanoparticles（MCN）with high photothermal conversion efficiency were designed and prepared,and their physicochemical and in vitro-related biological properties were characterized.The results showed that the doping of lanthanide neodymium（Nd）into whitlockite（WH）by the subcritical hydrothermal method was successful,and the doping of an appropriate amount of Nd³⁺did not change the crystalline phase of WH;the addition of Nd³⁺imparted better photothermal and fluorescence response to WH;cytocompatibility and hemolysis experiments demonstrated that MCN was not cytotoxic and hepatotoxic;in vitro osteogenic differentiation experiments showed that MCN could In vitro osteogenic differentiation assays showed that MCN could upregulate ALP expression and mineralized nodule formation,further demonstrating the great potential of MCN for bone repair（2）A photothermally responsive magnesium phosphate bone cement（NTMPC）system was constructed by combining MCN with trimagnesium phosphate bone cement（TMPC）,and its physicochemical and in vitro biological properties were characterized.The results showed that:the addition of MCN did not affect the hydration products of TMPC;NTMPC had high mechanical strength（over 40 MPa in1 day）and the setting time met the requirements of surgical operation（10-20 min）,and could be adjusted by temperature changes;the introduction of MCN imparted photothermally and fluorescence response properties to NTMPC;NTMPC had no significant The synergistic effect of NTMPC stent and thermal stimulation can significantly upregulate the expression of osteogenic genes and proteins;the synergistic effect of NTMPC stent and thermal stimulation can achieve the clearance of tumor cells and inhibit bacterial growth.（3）Micro-CT and histological staining results demonstrated that the synergistic effect of NTMPC and thermal stimulation showed a better ability to promote new bone production and better osseointegration between the scaffold and the host bone compared to the bone cement group without NIR thermal stimulation and photothermal responsiveness.The ability to promote new bone production and better osseointegration between the graft and host bone further validated the great potential of the synergistic effect of scaffold and physical stimulation to promote tissue regeneration.