Atomic layer deposition and characterization of biocompatible hydroxyapatite thin films

Atomic layer deposition (ALD) was used to produce hydroxyapatite from Ca(thd)(2) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) and (CH3O)(3)PO onto Si(100) and Corning (0211). Film crystallinity, stoichiometry, possible impurities and surface morphology were determined. The as-deposited films contained significant amounts of carbonate impurities however, annealing at moist N-2 flow reduced the carbonate content even at 400 degrees C. The as-deposited Ca-P-O films were amorphous but rapid thermal annealing promoted the formation of the hydroxyapatite phase. Mouse 3T3-E1 cells were used for the cell culture experiments. According to the bioactivity studies cell proliferation was enhanced on as-deposited ALD-grown Ca-P-O films and greatly enhanced on films annealed at 500 degrees C in comparison with reference cells on borosilicate glass or cell culture polystyrene. (C) 2009 Elsevier B.V. All rights reserved.