Polydopamine-loaded Metal Ions Modified PCL/β-TCP Scaffold For Bone Tissue Engineering

With the serious aging of the population,bone defects are becoming more and more common,which is a huge challenge for clinical treatment.The best way to treat bone defects is autologous bone transplantation.However,autologous bone transplantation still has some disadvantages,such as lack of available resources,lack of customization and related complications.Allogeneic bone transplantation does not have the problem of available resource supply,but it often fails due to severe immune rejection in the face of human antigenic reaction,especially when the graft is large.Still exist at present,the clinical use of metal,ceramic or polymer made of artificial bone substitute material,but these materials there are many problems,such as poor poor biocompatibility,biodegradable,mechanical properties and the host is not matching,and the problem of short service life of the emergence of the bone tissue engineering offers hope for reconstruction of bone tissue and repair.Natural bone is mainly composed of water,collagen and minerals,and HA is the main component of minerals.Usually,the method to treat bone defects is to induce the generation of HA to achieve autologous bone growth,so as to play the therapeutic effect.β-Tricalcium phosphate（β-TCP）is one of the bioactive ceramics,and its unique biodegradability,biocompatibility and bone induction are widely used in bone tissue engineering.However,due to the brittleness of single bioceramic scaffolds,other ductile materials are often needed to be used together.PCL is a kind of polyester with good toughness,biodegradable and bioabsorbable as well as good biocompatibility.It is generated by ring-opening polymerization reaction ofε-caprolactone.Its melting temperature is about 60℃lower and it is soluble in most organic solvents,so it can be processed in a very simple way.Due to the safety,reliability,accuracy,personalized design and strong functionality of 3D printing extrusion deposition technology,the preparation of porous PCL/β-TCP bone tissue engineering scaffolds based on 3D printing extrusion deposition technology will become a trend in bone tissue engineering.Using PCL andβ-TCP as raw materials,PCL/β-TCP bone tissue engineering scaffolds were prepared by 3D printing extrusion deposition technology.In addition,the mechanical properties,biocompatibility and bone inductance of PCL/β-TCP scaffolds were studied,and the best PCL/β-TCP bone tissue engineering scaffolds were selected.Then,Cu²⁺was introduced into the PCL/β-TCP scaffold surface to prepare Cu-PCL/β-TCP scaffolds.The mechanical properties of the scaffold were investigated,such as in vitro antibacterial properties,cytotoxicity and in vitro degradation simulation.The main research is as follows:1.Explore the 3D printing process parameters satisfying the bone tissue engineering scaffold2.Using PCL andβ-TCP as raw materials,PCL/β-TCP porous bone tissue scaffolds were prepared by 3D printing extrusion deposition technology.Meanwhile,the mechanical properties and biocompatibility of the scaffolds were analyzed.PCL40/β-TCP60 scaffold is more suitable for bone tissue engineering.2.Based on PCL/β-TCP porous scaffold,Cu-PCL/β-TCP porous scaffold was prepared by the strong adhesion of polydopamine and chelation of metal ions.The surface morphology,in vitro antibacterial properties and biocompatibility of the scaffold were analyzed.The results showed that dopamine self-polymerized into polydopamine particles under alkaline conditions,and the surface morphology of the scaffold was changed by the adhesion of polydopamine particles chelated with Cu²⁺.In vitro antibacterial activity indicated that the scaffold showed antibacterial properties after chelated with Cu²⁺,and the antibacterial properties increased with the increase of chelated Cu²⁺.The cytotoxicity test showed that the cytotoxicity of the scaffold increased with the increase of Cu²⁺content,but it still met the needs of bone tissue engineering.