Effect of β-TCP Size on Bone-Like Layer Growth and Adhesion of Osteoblast-Like Cells in Hydroxyapatite/β-TCP Composites

Abstract

Hydroxyapatite (HAp)-20 vol% β-tricalcium phosphate (β-TCP) composites were prepared. The effect of β-TCP size on bone-like layer growth and adhesion of osteoblast-like cells on the composites was systematically studied in vitro. When the composites were soaked in a simulated body fluid, the formation and growth rates of the bone-like layer increased with increasing β-TCP size, even if the volume fraction of β-TCP was constant. Moreover, selective dissolution of β-TCP phase and formation of the bone-like layer around the phase were frequently observed. Higher Ca²⁺ concentration due to the fast dissolution of β-TCP beneath the sample surface resulted in faster formation and growth of the bone-like layer, especially in the samples containing β-TCP powders larger than 100 μm. MC3T3-E1 osteoblast-like cells preferentially adhered to β-TCP phase in HAp/β-TCP composites because of the enrichment of Ca²⁺ ions around β-TCP.