Preparation And 3D Printing Research Of Monetite-based Biomaterials

Calcium phosphate materials have become a research hotspot in the field of bone repair and bone replacement because of their excellent biocompatibility and degradability.Monetite(MC)is transformed from Brushite(DCPD)and has excellent self-curing properties and the ability to inhibit osteoclasts compared with other calcium phosphate materials.Monetite has special solubility,porosity,surface area and inhibition of osteoclasts.After implantation in the human body,there are two pathways for bioresorption:passive lysis and active cellular resorption,thus providing a balance before resorption and new bone formation.This is an advantage of Monetite over Hydroxyapatite and Brushite.However,there are still many problems in the traditional synthesis of Monetite.Traditional calcium phosphate bone cement has some problems,such as long initial and final setting time,poor injectivity,weak cohesion and low mechanical properties.However,there are insufficient studies on the influence of particle size,particle distribution and blending liquid on printing effect of 3D printing paste of calcium phosphate cement,and the mechanical properties of printed scaffoldings are low.In addition,there are few studies on cell proliferation,cell migration and other biological properties of Monetite.In response to the above problems,this paper mainly carried out the following aspects:(1)In order to solve the problems of low purity and poor environmental friendliness existing in the traditional synthesis method of Monetite,a novel process was used to prepare Monetite powder,and the influence of the preparation process on the purity and morphology of Monetite was studied.A two-step hydrothermal method was used to prepare the MC powder with controllable morphology,small particle size and high purity.The study found that The best preparation process route of Monetie is in the pure water system,the ratio of calcium to phosphorus is 1,calcium nitrate is the calcium source,the hydrothermal temperature of the first step is 90℃,the hydrothermal time is 6 h,the hydrothermal temperature of the second step is 60℃,and the hydrothermal time is 18 h.(2)In order to solve the problems of traditional bone cement such as long initial and final setting time and poor injectable,Amorphous Calcium Phosphate/Monetite biocomposite bone cement was prepared,and the changes of properties,components and morphology of bone cement after hydration were studied.The study found that the optimal liquid-solid ratio of Monetite-based bone cement added with 50%ACP was 0.8,the initial and final setting times were 8 min and 15 min respectively,and the injectability was 75.4%,the surface morphology of cell adhesion and growth,all indicators meet the requirements.(3)In order to solve the problems of difficult printing of traditional bone cement and low mechanical properties of scaffolds,amorphous Calcium Phosphate/Monetite biocomposite bone cement scaffolds were prepared by extrusion 3D printing,and the effects of calcination and steam hydrothermal on the properties and morphology of the scaffolds were studied.The optimal liquid phase composition is 1wt%sodium alginate+2.5wt%gelatin.Calcining is not suitable for post-treatment of the stent,and the mechanical properties of the stent increase rapidly after steam-water heating.(4)The biological properties of Amorphous Calcium Phosphate/Monetite biocomposites were investigated.The biological properties of Monetite-based composite biomaterials were characterized by CCK-8 method,flow cytometry,Transwell,and immunofluorescence method.The study found that 25%ACP+75%MC composite biomaterial is beneficial to the adhesion,proliferation and osteogenic differentiation of BMSCs,and have a significant inhibitory effect to the adhesion,proliferation,differentiateon and osteolysis process of RAW164.7 osteoclast.