Study On Surface Modification And Pneumatic Extrusion Cryogenic 3D Printing Of PCL-HAW Composite Bone Scaffold

The clinical way of autologous bone transfer cannot meet the needs of patients,every year more than 2.2 million cases of bone transplant related surgery in bone repair material demand,the researchers found a calcium phosphorus ceramic powder material-hydroxyapatite(HA),is the mineral composition in the bones of the animal body,and the animal bones very similar physical,chemical and biological properties,get the favour of more and more researchers.When HA and polymer materials are combined,the composite materials have good plasticity,biocompatibility and bone conductivity,which provides a new treatment scheme and guiding significance for bone tissue repair,and has a bright application future.In this paper,hydroxyapatite nanowires(HAW)were prepared by hydrothermal method,the influence of different conditions on hydrothermal products was investigated by control variable method,and the main crystal phase composition of hydrothermal products was verified by XRD test,and the morphology of HAW was observed by scanning electron microscope(SEM)and the size similarities and differences were analyzed statistically.The suitable conditions for preparing HAW are summarized.At the same time,the micro and nano hydroxyapatite purchased by the laboratory and HAW prepared by the experiment were compared.The crystal phase of the two was analyzed by XRD,the specific surface area difference was detected by BET,and the biocompatibility of the two was tested by cell experiment.HA and HAW were mixed repectively with polycaprolactone(PCL)in a water bath at 65℃.The improvement effects of HA and HAW on hydrophilicity and mechanical properties of the composites were tested.The porous grid scaffolds were prepared by pneumatic 3D cryogenic printing technology,and the surface of the scaffolds was modified by self-induced crystallization,and the sheet crystal structure was formed on the surface.The effects of PCL-HAW modified porous scaffolds on the adhesion,growth,proliferation and differentiation of osteoblasts after self-induced crystallization were studied from macro and micro structure,phase composition,functional groups,mechanical properties and biocompatibility.According to the experimental results of this paper,it is concluded that the most suitable condition for HAW preparation is to prepare the reaction solution with the ratio of ethanol to pure water of 5:9,the p H is 7.8,and place the solution in the ultrasonic oscillator,the reaction vessel of ultrasonic oscillation for 2 hours is 100 ml reactor,and the reaction is kept in a drying oven at 180℃ for 24 hours.By comparing HA,HAW and PCL,it is found that HAW can significantly improve the compressive properties and hydrophilicity of the composites,and has better biocompatibility.PCL-HAW composite porous scaffold prepared by 3D printing technology through self-induced crystallization,the formation of flake crystal structure makes the scaffold surface more rough,which can provide a favorable environment for cell adhesion growth.The scaffolds with flake crystal structure also showed good hydrophilicity.All four scaffolds showed good biocompatibility and promoted osteogenic differentiation of osteoblasts,among which 01 P scaffolds had the best effect.In this paper,HAW synthesized by hydrothermal method is combined with PCL,and self-induced crystallization technology is used to modify the surface of PCLHAW porous composite scaffolds prepared by pneumatic 3D printing.This provides a new idea for the subsequent research and application of scaffold materials for bone tissue engineering,and proposes a new way to promote the composite use of ceramic materials and polymer.