Porous Alumina/Zirconia Composite Scaffold with Bioactive Glass 58S33C Coating

Abstract

Strong and tough, macroporous alumina/zirconia composites are superior to alumina scaffolds but still biologically inert to bone tissue, leading to poor tissue ingrowth and osteointegration. One way to solve this problem is applying a bioactive coating onto the pore walls of the macroporous composites. In this study, macroporous alumina/zirconia (20vol%) composites (scaffolds) were prepared by a vacuum infiltration method involving the use of strained (10%) compacts of the expanded polystyrene (EPS) beads (typically 1-2.8 mm in diameter). A bioactive glass (58S33C) coating (~ 20 μm) was applied on the pore walls of the macroporous composites by slurry dip coating and sintering at 1200 oC for 1 hour. A top or outer bioactive glass (58S33C) thin layer (< 10 μm) was further applied by sol dip coating and sintering at a low temperature (< 800 °C). The bioactive glass-coated macroporous alumina/zirconia composites had well interconnected pores, relatively large pore sizes (1-2 mm), medium porosities (60-66%), high compressive strengths (7.52 – 5.42 MPa), and high bioactivity (with an apatite layer formed within 24 hours in the simulated body fluid). The combination of the strong and ultrafine (if not nano-structured) macroporous scaffolds with the multiple or graded bioactive coatings represented a new generation of bone substitutes or permanent scaffolds for bone tissue regeneration.