Preparation And Evaluation Of Hydroxyapatite Bone Bio-Scaffold

Additive manufacturing technique is more and more widely applied to repairing bonedefects because of its many advantages, such as the capability of fabricating customizablestructure of implant and diversity of used materials and so on. This dissertation aimed tofabricate HA scaffolds that have customizable structures, complete shapes, highmechanical strength and good biocompatibility, through combining the extrusiondeposition method which is one of the additive manufacturing techniques with microwavesintering.At first, the critical parameters in preparation of HA slurry, extrusion depositionmethod and microwave sintering were studied and optimized in this dissertation. Themeasurements experiments of viscosity and deposit height of HA slurry showed that HAslurry can possess the best dispersion stability when the content of dispersant（Ammonium polyacrylate, PAA） was1wt%and PH=9.And based on the results above,35vol%HA slurry with moisture retention, good self-sustaining, moderate viscosity wasprepared.Scanning electron microscopy （SEM）, X-ray diffraction （XRD） and universalmaterial testing machine were used to observe, analyze and measure the microstructures,phase compositions and compressive strength of HA scaffolds prepared with differentparameters. After comparing and optimization, the parameters were chose as followings:during extrusion deposition method process, inner diameter of nozzle is0.34mm, nozzlerise height between two layers is0.35mm, synthetic movement speed of workbench inX-Y axis is5mm/s, extrusion speed of piston is0.0035mm/s, operating temperature is inthe range of15~25℃; during microwave sintering process, the pre-sintering temperatureis400℃, hold time is0.5h, final sintering temperature is1200℃, hold time is0.5h,heating rate is40℃/min. With such parameters, the scaffolds with porosity of50%wereprepared, having the compressive strength of46MPa.In the testing process, the osteosarcoma （SAOS-2） cells were cultured on preparedHA scaffolds for21days. The adhesion and proliferation of cells were observed through optical microscope to study the biocompatibility of HA scaffolds, the changes on surfacemetrology and surface morphology of HA scaffolds before and after cell culture wereobserved and measured by optical profilometry and SEM, to investigate the degradation ofHA scaffolds under cell culture. The results showed that during cell culture period,SAOS-2cells could attach to and grow on scaffolds well, cells also had a circle ofgrowth-death-growth, which prove the HA scaffolds was not toxic and could induce cellsto proliferate, so they had good biocompatibility. There was not an obvious difference ofsurface metrology and surface micro morphology before and after cell culture, that meansthere was nearly no degradation of HA scaffolds during the cell culture period of21days.In summary, customizable HA scaffolds with good compressive strength andbiocompatibility could be prepared through extrusion deposition method and microwavesintering.