Coprecipitation of cytochrome C with calcium phosphate on hydroxyapatite ceramic

Cytochrome C (cyt C), which has a molecular weight and an isoelectric point similar to those of fibroblast growth factor (FGF-2), was coprecipitated with calcium phosphates in the presence or absence of a hydroxyapatite ceramic (HAP) using supersaturated calcium phosphate solutions that can be prepared by mixing infusion fluids. The precipitates formed in the solution consisted of amorphous calcium phosphate in the absence of a HAP. In the presence of a HAP, precipitates morphologically identical to bone-like apatite formed a calcium phosphate layer on the surface of HAP. The optimum conditions for coprecipitation of cyt C with calcium phosphate on HAP were a Ca/P molar ratio of 1.5 and a NaHCO3 concentration of 7.90 mM. The release of cyt C from the calcium phosphate layer continued for at least 10 days in the physiological salt solution. The results suggest that FGF-2 is also expected to be coprecipitated with calcium phosphates onto HAPs using infusion fluids.