Association of calcium phosphate and fibroblast growth factor-2: a dynamic light scattering study

The size distributions of fibroblast growth factor-2 (FGF-2) in aqueous solutions with neutral pH were investigated with dynamic light scattering technique. We found that the FGF-2 was distributed in dimer or trimer form at concentration of 0.1-1.0 mg.mL(-1). An aggregate with a hydrodynamic radius approximately 90 nm coexisted with this and its proportion increased with a decrease in concentration. At lower concentrations (less than 0.10 mg.mL(-1)) FGF-2 aggregates with an average radius of 80-100 nm were dominant and were stable for more than a day. These FGF-2 solutions were mixed with calcium phosphate solutions to produce a sub-micron sized compound of FGF-2 and hydroxyapatite, which could be used as a biological implant that possessed a pharmacological function for bone formation. By utilizing a transformation from amorphous calcium phosphate to hydroxyapatite, FGF-2 was effectively incorporated into polycrystals of hydroxyapatite.