The Construction Of ROS Responsive Bio-functional Titanium Interface And Its Effect On Osteoporotic Fracture Repair

Titanium and its alloys have been widely used in biomedical fields such as bone repair due to their excellent mechanical properties and biocompatibility.However,the interface bio-inertness of titanium reduces the integration of implant and host bone,leading to implant loosening and surgical failure.Especially for osteoporosis patients,the high brittleness and low bone greatly increase the risk of loosening and displacement of titanium-based implants.Based on this,how to design and optimize the surface properties of titanium-based materials and promote the integration of materials and host bone has important practical significance for the improvement of osteoporotic fracture repair especially.Based on the special microenvironment(high ROS level)of osteoporosis,in order to promote the repair of osteoporotic fracture,a bio-functional interface with ROS response was constructed on titanium-based materials by simple amide reaction and electrochemical deposition.The main research contents and results are as follows:1.Preparation and characterization of ROS responsive functionalized titanium interface.Firstly,the hydroxyapatite(HA)coating was deposited on the surface of titanium by electrochemical deposition,and the OGP modified by phosphoric acid group was adsorbed on the surface of HA by coordination.Then,the NBC(4-nitrophenyl4-(4,4,5,5-tetramethyl-1,3,2-dioxa borolan 2)benzyl carbonate)small molecule was used to combine Apt 19S and OGP to obtain the ROS responsive bio-functional interface.The surface properties were characterized by H NMR,X-ray photoelectron spectroscopy,field emission scanning electron microscopy and contact angle measurement.2.Optimization of ROS responsive functionalized titanium-based interface.To determine the suitable loading amount of OGP and Apt 19S on the titanium-based interface for recruiting bone marrow mesenchymal stem cells(MSCs)and promoting their differentiation,we explored the loading efficiency of OGP and Apt19S in different concentrations and their cumulative release behavior.3.The effect of ROS responsive functional titanium interface on MSCs migration and differentiation.To explore the influence of ROS responsive functional titanium substrate on MSCs migration in H₂O₂ environment,transwell migration test,gelatin zymogram,wound healing test and expression of integrin,FAK and vimentin at protein level were performed.The cells behavior of MSCs inclucing spread,proliferation and differentiation on ROS responsive functional titanium interface in H₂O₂ environment were studied by using tetrazolium salt colorimetry,alkaline phosphatase(ALP)staining,alizarin red staining,calcium production,protein and m RNA levels.The results showed that this titanium based responsive interface can significantly promote the proliferation,migration and osteogenic differentiation of MSCs.4.The study of ROS responsive functional titanium interface in osteoporotic fracture repair.In order to investigate the effect of titanium based responsive interface on osteogenesis in vivo,the functional titanium rod was implanted into the osteoporosis model animal body.To evaluate stem cells recruitment and new bone formation induced by this functional titanium rod in vivo,X-ray,CD29/CD90 immunohistochemical staining and hematoxylin eosin staining were used.The results showed that ROS responsive functional titanium-based interface can effectively recruit stem cells to the implant interface and promote the formation of new bone around the implant.It provides new strategy for the repair of osteoporotic fracture.