Bioresorbable β-TCP-(Fe-Ag) nanocomposites with the high (70 vol.%) content of the β-TCP (tri-calcium phosphate) ceramic phase were prepared by high energy attrition milling of micron- and nano-size powders of Fe, Ag2O and β-TCP followed by high pressure consolidation/cold sintering at room temperature. Macroporous β-TCP-(Fe-Ag) scaffolds with 50 to 80% open porosity were prepared employing the combination of cold sintering and the modified salt-leaching method, using 200-300 µm precompacted matrix granules and highly water soluble K2CO3 porogen particles of the comparable size. The fabricated macroporous scaffolds exhibited an interconnected open-cell architecture with an average pore size of 250 µm and compressive strengths of approximately 12 and 9 MPa for the 50 and 60% porous scaffolds, respectively. The use of precompacted granules instead of the loose β-TCP-(Fe-Ag) nanocomposite powder allowed us to increase the scaffold permeability an order of magnitude, e.g., to 6-7× 10-10 m2 at 50% porosity. Both the permeability and strength values were found to depend on the scaffold porosity and on the size and shape of K2CO3 porogen particles. After 4 weeks immersion in saline solution at 37?C, the scaffolds lost 4-5% weight and retained about 50% of their initial strength. In vitro tests in human osteoblast monocultures and osteoblast-endothelial cell co-cultures indicated that β-TCP-(Fe-Ag) nanocomposites are biocompatible for the growth and survival of both cell types. The attractive combination of high strength, high permeability and cell compatibility makes the developed highly porous open cell β-TCP-(Fe-Ag) structures a potentially useful resorbable scaffold material for bone regeneration in load bearing body locations.
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