Continuous crystalline carbonate apatite thin films. A biomimetic approach

In contrast to extensive studies on hydroxyapatite thin films, very little has been reported on the thin films of carbonated apatite (dahllite). In th is report, we describe the synthesis and characterization of a highly cryst alline dahllite thin film assembled via a biomimetic pathway. A free-standi ng continuous precursor film of carbonated calcium phosphate in an amorphou s phase was first prepared by a solution-inhibited templating method (templ ate-inhibition) at an air-water interface. A stearic acid surface monolayer acted as the template, while a carbonate-phosphate solution composed a bin ary inhibition system. The precursor film formed at the air/water interface was heated at 900 degreesC and transformed into a dense crystalline film t hat retained the overall shape of the precursor. The crystalline phase was characterized by XRD and IR to be a single-phase carbonate apatite, with ca rbonate substitutions in both type A (OH-) and type B (PO43-) lattice posit ions.