Porous hydroxyapatite-dodecylphosphate composite film on titania-titanium substrate

Synthetic analogues of bone are being actively pursued as materials for biomedical applications in the field of bone replacement, augmentation and repair. Numerous stringent criteria have to be met for a biomaterial to be considered as an acceptable bone implant, including the ability to integrate into bone and not cause any deleterious side effects. In this article we describe a materials chemistry approach to synthesizing a new type of bone implant material. The strategy involves the spontaneous growth, under aqueous physiological pH conditions, of an oriented hydroxyapatite film with micron dimension porosity, on the surface of a layer of TiO2, that has been sputter deposited on Ti metal. This procedure creates desirable co-crystallized phases of hydroxyapatite (OHAp) and octacalcium phosphate (OCP) with preferred orientation respectively along the [001] and [101] directions. Subsequently, a calcium dodecylphosphate mesolamellar phase has been grown within these oriented porous films to create a multilayered chemical composite CaDDP-OHAp-TiO2-Ti in which the CaDDP phase is stereochemically and charge matched with the OHAp.