Influence of the precipitation temperature on properties of nanohydroxyapatite powder for the fabrication of highly porous bone scaffolds

The aim of the present work is to study the influence of the precipitation temperature in the synthesis of nanohydroxyapatite (n-HAp) on the properties of the resulting n-HAp powder for the fabrication of highly porous scaffolds for bone tissue engineering. The n-HAp powder was obtained by a wet precipitation technique starting from calcium nitrate tetrahydrate (Ca(NO3)(2)*4H(2)O) and phosphoric acid (H3PO4) at different temperatures: 10 degrees C, 37 degrees C and 50 degrees C. Highly porous scaffolds were fabricated using the three different powders by the sponge replica method and sintering at 1300 degrees C. Combined X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses on powders indicated that on increasing the precipitation temperature the formation of pure n-HAp is accelerated, without significant changes in particles morphology and size. Scaffolds characterized by high porosity (89%) and good compressive strength (0.53 MPa for n-HAp prepared at 37 degrees C) were obtained. XRD analyses on sintered n-HAp confirmed the thermal stability of the material. Therefore, the as-synthesized n-HAp powder can be successfully used for the fabrication of highly porous scaffolds as bone substitutes.