A novel non line-of-sight method for coating hydroxyapatite onto the surfaces of support materials by biomineralization

A novel method is described for the non line-of-sight coating of hydroxyapatite onto polyurethane reticulated foam and titanium discs. This utilises a biofilm of Serratia sp. NCIMB 40259 which, when challenged with a solution containing calcium chloride and phosphatase substrate, manufactures biofilm-bound material identified as hydroxyapatite by X-ray powder diffraction analysis. Non-invasive magnetic resonance imaging was used to visualize the biofilm coating throughout the foam labyrinth and to measure the thickness of the film within reticulated foam cubes in situ. The film developed within the cube matrices was similar to that measured on the surface of a glass slide. Using LaPO4 deposition as a model system the metallised biofilm was visualised in two-dimensional slices throughout three-dimensional images acquired by magnetic resonance imaging. A similar encrustation of hydroxyapatite on the surface of biofilm grown on titanium discs was confirmed by scanning electron microscopy. Potential applications for bio-hydroxyapatite as possible bone implant precursors are discussed.