Published online by Cambridge University Press: 01 February 2011
The orientation distribution of crystalline grains in calcium phosphate coatings produced by pulsed laser deposition was investigated using an X-ray pole-figure diffractometer. Increased laser energy density of a KrF excimer laser in the 4–7 J/cm2 range leads to the formation of hydroxyapatite grains with the c-axis preferentially aligned perpendicularly to the substrates. This preferred orientation is most pronounced when the plume direction of incidence is normal to the substrate. This crystallographic texture of hydroxyapatite grains in the coatings is associated with the highly directional and energetic nature of the ablation plume. Anisotropic stresses, transport of hydroxyl groups, and dehydroxylation effects during deposition all seem to play important roles in texture development. Studies of cell adsorption using human Mesenchymal stem cells reveal that hydroxyapatite coatings with strong texture and random orientation show different cell adsorption behavior, which is consistent with the notion that protein attach differently on different faces of hydroxyapatite crystals. Cells seeded on textured coatings exhibit better spreading and adhesion compared to those placed on randomly oriented coatings.