Preparation And Properties Of Porous BCP Scaffolds With Unidirectional Pore Structure

In view of the deficiency of small pore width and poor mechanical properties of unidirectional porous calcium phosphate ceramics prepared by freeze drying, ice crystal template- freeze drying method was used to fabricate the porous biphasic calcium phosphate(BCP) ceramic scaffolds with unidirectional pore structure in this paper. The porous BCP as bone defect repair materials with good structure and properties were obtained by optimizing the firing system, regulating by the pore structure adding the additive(Na Cl, et al), and improving the mechanical properties by infiltrating the le cithin- modified PLGA solution and adding phosphate-based glass(PG) as sintering agent.The BCP scaffolds with unidirectional pore structure were fabricated by sintering the freeze-dried the BCP slurries, which were prepared by mechanically mixing deionized water with β-TCP powders(D50 = 7.554 μm) and HA powders(D50 = 12.024 μm). The sintering system of porous BCP scaffolds was optimized by investigating the influence of sintering temperature(1000 ~ 1300 °C) and holding time(2, 4, 6 h) on the phase composition, porous structure and compressive strength. The pore widths of unidirectional porous BCP scaffolds were significantly increased by adding Na C l to the slurry. When the concentration of Na C l was 10 wt.%, the average diameter of pores perpendicular to the freezing direction was about 111.27 μm, and the compressive strength of BCP scaffolds were significantly enhanced. The slurries with polyethylene glycol(PEG) and polyvinyl pyrrolidone(PVP) could not promote the increase of the ice crystal size to obtain porous BCP scaffolds with larger pore width. Porous composite scaffolds with good mechanical properties were fabricated by infiltrating the modified PLGA solution and adding PG as sintering agent. When the concentration of PG was 17.5 wt.%, the compressive strength and porosity of porous PG/BCP scaffolds was about 5.7 MPa and 55.9 %, respectively. The compressive strength and compression deformation of PLGA/BCP scaffolds was about 7.8 MPa and 40 %, when the concentration of PLGA solution used for infiltration was 0.075 g/ml. The weight loss of PG/BCP and PLGA/BCP was less than 10 % after immersion in PBS for 28 days. The cell experiment results showed that cells spread well and proliferated fine on the porous PG/BCP and PLGA/BCP scaffolds, demonstrating their good biocompatibility. PG/BCP and PLGA/BCP sca ffolds were expected to further improve for the application in bone defect area.