A room temperature camphene-based freeze-casting method was used to fabricate hydroxyapatite/tricalcium phosphate (HA/TCP) ceramic scaffolds. By varying the solid loading of the mixture and the freezing temperature, a range of structures with different pore sizes and strength characteristics were achieved. The macropore size of the HA/TCP bioceramics was in the range of 100-200 mu m, 40-80 mu m and less than 40 mu m at solid loadings of 10, 20 and 30 vol.%, respectively. The initial level of solid loading played a primary role in the resulting porosity of the scaffolds. The porosity decreased from 72.5 to 31.4 vol.% when the solid loading was increased from 10 to 30 vol.%. This resulted in an increase in the compressive strength from 2.3 to 36.4 MPa. The temperature gradient, rather than the percentage porosity, influenced the pore size distribution. The compressive strength increased from 1.95 to 2.98 MPa when samples were prepared at 4 degrees C as opposed to 30 degrees C. The results indicated that it was possible to manufacture porous HA/TCP bioceramics, with compressive strengths comparable to cancellous bone, using the freeze-casting manufacturing technique, which could be of significant clinical interest.
Macchetta, A., Turner, I. G., & Bowen, C. R. (2009). Fabrication of HA/TCP scaffolds with a graded and porous structure using a camphene-based freeze-casting method. Acta Biomaterialia, 5(4), 1319-1327. https://doi.org/10.1016/j.actbio.2008.11.009