Fabrication And Biocompatibility Characterization Of Porous Alumina Hydroxyapatite Composites Prepared By Protein Foaming-Consolidation Method

Abstract

Porous alumina ceramics have been attracting considerable attention for cell loading and bone grafts. Although porous alumina provides relatively high mechanical properties in respect to bioactive porous ceramics, the bioinertness of alumina hamper its application for for permanent bone implant. On the other hand, the use of hydroxyapatite (HA) for bone surgery is highly succesful due to its biocompatibility, bioactivity and osteoconduction characteristics. Its is therefore attractive to combine the mechanial properties of alumina with the bioactive of hydroxyapatite for bone generation. This report presents fabrication and biocompatibility test of porous alumina–hydroxyapatite composites fabricated through protein foaming–consolidation technique. Alumina and sol-gel derived HA powder were mixed with yolk and starch at an adjusted ratio to make slurry. The resulting slip was poured into cylindrical shaped molds and followed by foaming and consolidation via 180°C drying for 1 h. The obtained green bodies were burned at 600°C for 1 h, followed by sintering at temperatures of 1200–1550°C for 2 h. Porous alumina–HA bodies with 26–73 vol.% shrinkage, 29%–52% porosity and 0.1–4.9 MPa compressive strength were obtained. The compressive strength of bodies increased with the increasing sintering temperatures. The addition of sol-gel derived HA in the body was found to decrease the compressive strength. Biocompatibility study of porous alumina–HA was performed in a stirred tank bioreactor using culture of Vero cells. A good compatibility of the cells to the porous microcarriers was observed as the cells attached and grew at the surface of microcarriers at 8–120 cultured hours. The cell growth on porous alumina microcarrier was 0.015 h−1 and increased to 0.019 h−1 for 0.3 w/w HA-to-alumina mass ratio and decreased again to 0.017 h−1 for 1.0 w/w ratio. Carbon concentration on porous alumina bodies without addition was 36.03%; it significantly increased 46.14 when 1.0 w/w HA was added.