S.I Roohani Esfahani - Department of Materials Engineering, Isfahan University of Technology, ۸۴۱۵۴, Iran
r Emadi
f Tavangarian
m Karbasi

Highly porous scaffolds with open structure are today the best candidates for bone substitution to ensure bone oxygenation and angiogenesis [1]. The reduced mechanical strength of highly porous, i.e. greater than 80% porosity HA scaffolds is a major drawback. Various efforts have been done for improvement of mechanical properties of highly porous ceramic scaffolds. Kim et al. [2] developed a highly porous HA (~86%) by polymer-sponge method with compressive strength of 0.21 MPa. In another work, these researchers [3] developed a composite coatings (Hydroxyapatite/poly(ε-caprolactone) on the porous hydroxyapatite and enhanced the compressive strength to 0.45. Tian et al. [4] improved compressive strength of porous HA (~82.46%) from 0.34 MPa to 0.8 MPa by developing PLLA onto the framework of sintered HA scaffold. Miao et al. [5] achieved the astounding results. They enhanced the compressive strength of porous HA (~86%) From 0.1 MPa to 2.39 MPa by impregnation of scaffold in PLGA–bioactive glass slurry and coating the struts, although the composition of HA scaffold consisted of high amounts of TTCP (tetracalcium phosphate) and ß-TCP. The present study developed a nanostructured bioactive glass coated HA scaffold with porosity about 83% and compressive strength about 1.49 MPa. These scaffolds possessed high compressive strength in comparison with other HA scaffolds with similar porosities moreover in this research, polymeric materials were not used as a coating material. SC-800 scaffolds (sintered scaffolds at 800ºC with 2 h holding time) showed remarkable bioactivity and degradability simultaneously. Formation of crystalline phase (Si2PO7) during the sintering remarkably decreased the ability of Ca-P formation and the rate of degradation but enhanced mechanical property. The SC-800 scaffolds showed not only significant bioactivity but also good degradability and suitable mechanical property.