Thin film of low-crystalline calcium phosphate apatite formed at low temperature

Surface modification of biomaterials to improve biocompatibility without ch anging their bulk properties is desired for many clinical applications and has become an emerging technology in biomaterial research and industry. In the present study, a simple method of coating the solid surfaces of metals, organic tissue matrices, glasses, inorganic ceramics as well as organic po lymers with a thin film of low-crystalline apatite crystals (LCA) was devel oped. Acidic solution containing calcium and phosphate ions was neutralized with alkaline solution to form calcium phosphate precipitates at low tempe rature. Precipitates of solid calcium phosphate particles were, then, remov ed by filtration. Concentration of free ions in the filtered ion solution w hich were not involved in the formation of calcium phosphate precipitate wa s high enough to induce the heterogeneous nucleation on the solid surfaces at low temperature. Thin layers of calcium phosphate crystals were formed o n the surfaces of metals, glasses, inorganic ceramics, organic polymers inc luding hydrophobic ones, and biological tissue matrices with this solution. The thin layer of crystals consisted of poorly crystalline calcium phospha te apatite crystals which contain high amount of labile ions like bone crys tals and did not dissolve in the physiologic solutions. Various cells attac hed to this crystal layer and proliferated well. (C) 2000 Elsevier Science Ltd. All rights reserved.