Synthesis and characterization of bone analogue materials

grantor: University of TorontoSynthetic 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. Different approaches to a bone implant materials are introduced. A materials chemistry approach to synthesizing a new type of bone analogue material is described. 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 TiO\sb2 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. In an attempt to mimic the hierarchical organic-inorganic composite construction of bone, a calcium dodecylphosphate ester mesolamellar phase has been integrated into these oriented porous films to create a CaDDP-OHAp-OCP-TiO\sb2-Ti multilayer architecture. The nucleation and growth processes, together with the characterization of these films, are investigated using a multi-analytical approach based upon PXRD, SEM, TEM, SAED, XPS, FT-IR microscopy and profilometry. The relationship of the synthetic calcium phosphate composite materials to bone as well as other bone analogue materials is discussed.M.Sc

Solventless acid-free synthesis of mesostructured titania: Nanovessels for metal complexes and metal nanoclusters

A new and highly reproducible method to obtain mesostructured titania materials is introduced in this contribution. The meso-structured titania is obtained by employing self-assembled structures of non-ionic alkyl-poly(ethylene oxide) surfactants as templates. The materials are produced without additional solvents such as alcohols, or even water. Only the titanium(iv) ethoxide and the surfactant (C12EO10) are needed. Water, in the form of that attached to the surfactant and from the atmosphere, induces growth of titania nanoclusters in the synthesis sol. It is indicated that these nanoclusters interact with the surfactant EO-head groups to form a new titanotropic amphiphile. The new amphiphiles self-assemble into titanium nanocluster-surfactant hybrid lyotropic phases, which are transformed to the final mesostructured materials by further condensation of the titania network. The titania materials can be obtained also with noble-metal particles immobilized in the mesostructured framework. It is seen that when different metal salts are used as the metal precursors, different interactions with the titania walls are found. The materials are characterized by X-ray diffraction (XRD), polarization optical microscopy (POM), transmission electron microscopy (TEM), UV-vis spectroscopy, and micro-Raman analysis

Solventless Acid-Free Sythesis of Mesostructured Titania : Nanovessels for Metal Complexes and Metal Nanoclusters

A new highly reproducible method to obtain mesostructured titania materials is introduced in this contribution. The meso-structured titania is obtained by employing self-assembled structures of non-ionic alkyl-poly(ethylene oxide) surfactants as templates. The materials are produced without additional solvents such as alcohols, or even water. Only the titanium(IV) ethoxide and the surfactant (C12EO10) are needed. Water, in the form of that attached to the surfactant and from the atmosphere, induces growth of titania nanoclusters in the synthesis sol. It is indicated that these nanoclusters interact with the surfactant EO-head groups to form a new titanotropic amphiphile. The new amphiphiles self-assemble into titanium nanocluster-surfactant hybrid lyotropic phases, which are transformed to the final mesostructured materials by further condensation of the titania network. The titania materials can be obtained also with noble-metal particles immobilized in the mesostructured framework. It is seen that when different metal salts are used as the metal precursors, different interactions with the titania walls are found. The materials are characterized by X-ray diffraction (XRD), polarization optical microscopy (POM), transmission electron microscopy (TEM), UV-vis spectroscopy, and micro-Raman analysis

Synthesis of Acicular Goethite with Surfactants

Goethite nanotubes have been synthesised using polyethylene oxide surfactant as a directing agent. The surfactant enables the goethite to crystallise along a specific pathway and does not affect the crystal structure of the mineral but rather the agglomeration of the mineral. The crystals reach an optimum size at which the surfactant can bond