Manufacturing of highly porous calcium phosphate bioceramics via gel-casting using agarose

There is a technological need for highly porous bioceramics to be produced in an environmentally friendly manner. Gel-casting of highly porous HAp-(alpha-TCP) (CaP) foams using agarose as a gelling agent was investigated. Foaming of gel-cast suspension was performed at the temperature of 60 degrees C followed by transformation of the foams from a liquid state to a gelled state by cooling them to 15 degrees C. The sintered (1250 degrees C, 2 h soaking time) foams were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N(2) adsorption isoterm and Hg porosimetry. XRD study revealed that additives used in the gel-casting process did not influence the phase composition of the investigated materials. The macroporous microstructure of HAp-(alpha-TCP) foams was typically composed of approximately spherical pores (cells) interconnected by circular windows. The foams exhibited a broad pore size distribution with cells and windows ranging from 250 to 900 mu m, and from 25 to 250 mu m, respectively. The mode for spherical pore size was approximately 500 mu m while the above value for window was similar to 100 mu m. Additionally, the small amount of wall microporosity in the range of 0.2-0.9 mu m was confirmed by SEM and Hg porosimetry. The obtained porous (P = 90%) HAp-(alpha-TCP) scaffolds with interesting two types of macropores and a small amount of micropores seem to be a promising bone substitution material. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.