Optimization And Construction Of Titanium-based Surface By Gradient High-throughput Experimental Platform And Study On Its Bioadaptability

With the increasingly serious problem of population aging and the continuous improvement of people’s health requirements,the number of implants used in the replacement of spine,joints and other parts in orthopedic clinic has increased dramatically.Because of its excellent mechanical properties and biocompatibility,titanium-based implants have become one of the main metal implant materials in orthopedic clinic.Nevertheless,with the increase of applications,the problem of implant failure is prominent.Among them,bacterial infection and loosening caused by biological inertia are the two main reasons for implant failure.To solve this problem,bioactive peptides have been widely used for surface modification of implants,because of their excellent bioactivity.During the process of surface modification,whether it was single-or multi-functional surface,the optimization of peptide density is very important.Low density will lead to insufficient bioactivity,while high grafting density will produce side effects.In addition,on the surface of multi-functional implants modified by mixed peptides,the density of unoptimized peptide may also inhibit or shield the activity of other peptides.At present,most studies use orthogonal experiment to optimize the biological properties of implant surface,but this method needs a lot of time and power.In view of this difficulty,this paper developed a gradient high-throughput experimental platform for rapid optimization and construction of functional titanium-based implants,and selected a variety of optimized functional titanium-based implants with different biological activities.The main work mainly includes the following four parts:(1)Five single-functional gradient high-throughput experimental platforms were constructed on the titanium-based implants,which were used to screen the optimal single-functional surfaces with antibacterial,cell adhesion,osteogenic differentiation,angiogenic differentiation or neurogenic growth properties.The constructed high-throughput experimental platform can quickly screen out the best grafting density of five bioactive peptides on the implants,and the corresponding region has the best biological properties.At the same time,the preparation parameters of the corresponding area in the high-throughput experimental platform can be extracted quickly and accurately to prepare uniform functional implants,and it has the corresponding best biological performance.(2)Aiming at the main problems such as bacterial infection and loosening in the application of orthopedic implants,the high-throughput experimental platform based on AMP and RGD was constructed on the titanium-based implants.The platform can screen out the best grafting ratio and grafting density of AMP and RGD,and the preparation parameters of the corresponding region can be extracted quickly and accurately for the preparation of multifunctional surface with excellent antibacterial ability and biocompatibility.The prepared TiDual-P4 has a high inhibition rate of 98.2% against the orthopedic clinical pathogen Staphylococcus aureus(S.aureus);At the same time,this antibacterial implant overcomes the cytotoxicity of traditional antibacterial materials and shows excellent biocompatibility for mouse bone marrow mesenchymal stem cells(m BMSCs).(3)Aiming at the three important biological properties of osteogenesis,angiogenesis and neurogenesis in the process of bone repairing,the orthogonal complementary gradient highthroughput experimental platform based on YGFGG,QK and IKVAV was constructed on the titanium-based implants.By this platform,945 groups of data were collected quickly and accurately,and machine learning analysis was carried out to reveal the grafting kinetics of three peptides and the influence of each other on their biological properties.On this basis,the optimal grafting ratio and grafting density of three peptides were selected,and the preparation parameters of the corresponding regions were extracted.The optimal multi-functional surface Ti-(Y+Q+I)constructed by preparation parameters can simultaneously promote the osteogenic differentiation of human bone marrow mesenchymal stem cells(h BMSCs),the angiogenic differentiation of human umbilical vein endothelial cells(HUVECs)and the neurogenic growth of Schwann cells(SCs).(4)Two models of bone defect and bone defect with bacterial infection were constructed in New Zealand white rabbits are applied to study the biocompatibility of functional titaniumbased implants optimized by different high-throughput experimental platforms in vivo.It was found that Ti-Dual-P4 optimized by the binary peptides parallel complementary gradient highthroughput experimental platform of AMP and RGD can show excellent bone integration performance in the bone defect model;In the bone defect with bacterial infection model,it can effectively inhibit bacterial infection,reduce peripheral inflammatory cells and ensure bone integration.On the other hand,Ti-(Y+Q+I)optimized by the ternary peptides orthogonal complementary gradient high-throughput experimental platform based on YGFGG,QK and IKVAV,compared with the corresponding single-and dual-functional surfaces,it can promote bone integration through the synergy of three biological properties in the bone defect model.To sum up,this paper successfully designed and developed a high-throughput experimental platform for optimizing the functional surface of peptides for titanium-based implants with large clinical volume and wide range.The multi-functional titanium-based implants optimized by this platform can overcome the limitations of single-functional titanium-based implants,meet the complex needs of a variety of biological properties in the process of bone repair,and show excellent biocompatability in vivo.Relevant research provides an effective strategy for optimizing the functional surface and constructing titanium-based implants to meet clinical needs efficiently and accurately.