Study On Preparation And Drug Release Characteristics Of Drug-bearing Tissue Engineering Bone Scaffolds

The permanent repair of large bone defects caused by bone tuberculosis disease is a huge problem in modern orthopedics clinical medicine,while tissue engineering provides a new feasible idea for it.Tuberculosis lesions are covered with fibrous connective tissue to form sclerotic bone,which results in the slow surrounding blood flow,obstruction of the medicine from reaching the focus area,and leads to the failure of bactericidal action.In addition,the closed hypoxia environment causes the bacterial colonies breed and leads to hardened bone necrosis,which is a potential possibility of relapse of mycobacterium tuberculosis.To solve the local long-term effective release of anti-tuberculosis drugs,to ensure the repair and reconstruction of bone defects.The preparation of the drug-loaded tissue engineering bone scaffold,selection of drug carrier materials,and construction of drug release mechanism were studied.Firstly,this paper selects hydroxyapatite(HA),silk fibroin(SF)and polyvinyl alcohol(PVA)as medicine release carrier materials,and make use of implantable sustained release medicine delivery system to evenly blend and mix medicine and the carrier material through different processing methods.On the basis of 3D printing technology,it's feasible to develop the co-axial medicine-bearing nozzle equipment on the platform of the mechanical extrusion device and the coaxial medicine-loaded bone scaffold.Moreover,based on this,through the comparison of mechanical properties,micro-morphology,molecular structure and biocompatibility of different preparation schemes,the final result is that SF-PVA(1:4)composite gel heated by water bath shows excellent comprehensive performance.The medicine carrier materials are mixed according to the proportion to satisfiy 3D printing.HA/PVA,HA/SF-PVA,core HA/SF-PVA and outer HA/PVA medicines are separately prepared drug-loaded bone scaffolds for the degradation of drug-eluting bone scaffolds in terms of pH,SEM,degradation rate,and mechanical properties.The change analysis showed that the degradation performance of the coaxial drug carrier bone scaffold was basically consistent with the new bone growth rate.Finally,an implantable medicine release mechanism is used to establish three carrier medicine delivery system models,impregnation-implantable,uni axial-mixed implantable,and coaxial-mixed-implantable are contained.Taking RFP as model medicine,and combine engineering process method to determine the mixing ratio of the loaded bone scaffold material,the platform speed and the extrusion speed to form a three-dimensional porous bone carrier.In order to investigate SF content,RFP content,and medicine delivery system model's impact on the sustained-release properties of medicine-loaded bone scaffolds,making use of Design Expert software to obtain the relationship among three dependent variables through response surface methodology,to construct regression model and achieve significance analysis,and to obtain the most optimization parameters in the end.Through integrating the medicine-loaded bone scaffold degradation performance and medicine release performance,it could reduce the initial release concentration of the co-axially implanted medicine-loaded bone scaffold,relieve the phenomenon of bursting,and achieve sustained and effective concentration release.