Effect of coprecipitation temperature on the properties and activity of fibroblast growth factor-2 apatite composite layer

Fibroblast growth factor-2 (FGF-2) apatite composite layers were formed on anodically oxidized titanium (Ti) rods at temperatures lower than the previously used 37 degrees C to reduce the risk of the inactivation of FGF-2 in calcium phosphate solution. A two-step procedure was used to coprecipitate FGF-2 apatite composite layers on Ti rods. Continuous and homogeneous carbonate-containing low-crystalline apatite layers incorporating FGF-2 were formed on the surface of the Ti. The amounts of apatite and FGF-2 coprecipitated on the Ti rod surface decreased with decreasing coprecipitation temperature. When the coprecipitation temperatures were 15 and 20 degrees C, the amounts of FGF-2 precipitated on the Ti rods were 0.19 +/- 0.03 and 0.20 +/- 0.03 mu g/cm(2), respectively. A cell proliferation assay for evaluating the mitogenic activity of FGF-2 immobilized in the layer showed that when FGF-2 was coprecipitated at 15 and 20 degrees C, the number of NIH3T3 cells cultured with FGF-2 extract was significantly larger than that at 4, 10, 25 and 30 degrees C. To obtain the largest amount of active FGF-2 on a Ti surface, a temperature of 15 or 20 degrees C should be used for coprecipitating FGF-2. (c) 2008 Elsevier B.V. All rights reserved.