Growth, characterization and biocompatibility of bone-like calcium phosphate layers biomimetically deposited on metallic substrata

Much research has been devoted to the coating of orthopedic and dental implants with porous ceramics, such as hydroxyapatite to increase hard tissue integration in vivo. Chemical immersion in simulated body fluids and supersaturated calcium-phosphate solutions (SCPS) have been shown to elicit apatite coatings on the order of 10-100 mu m of thickness, which are very homogenous and would be more favorable to biological interaction than plasma-sprayed coatings. This study focuses on the growth, characterization and biocompatibility of bone-like apatite layers on metallic biomaterials produced through diminished time duration chemical immersion. The method presented here includes a pre-calcification step, in which samples were immersed in a boiling Ca(OH)(2) solution to initiate and increase favorable ion exchange prior to immersion. Subsequent immersion in SCPS produced homogenous coatings of calcium phosphate with a thickness of 20-30 mu m, 100% coverage and crystal sizes of 1-2 mu m in 3 days. Coated samples were favored biologically over non-coated samples by osteoblast cells as indicated by alkaline phosphatase activity. This study suggests that an industrially viable method of chemical immersion in a SCPS, coupled with simple pre-treatments can produce calcium phosphate coatings that favor positive biological interactions, conducive to osseointegration. (c) 2005 Elsevier B.V. All rights reserved.