title: Hierarchically structured titanium foams for tissue scaffold applications.
abstract: We present a novel route for producing a new class of titanium foams for use in biomedical implant applications. These foams are hierarchically porous, with both the traditional large (>300μm) highly interconnected pores and, uniquely, wall struts also containing micron scale (0.5-5μm) interconnected porosities. The fabrication method consists of first producing a porous oxide precursor via a gel casting method, followed by electrochemical reduction to produce a metallic foam. This method offers the unique ability to tailor the porosity at several scales independently, unlike traditional space-holder techniques. Reducing the pressure during foam setting increased the macro-pore size. The intra-strut pore size (and percentage) can be controlled independently of macro-pore size by altering the ceramic loading and sintering temperature during precursor production. Typical properties for an 80% porous Ti foam were a modulus of ∼1GPa, a yield strength of 8MPa and a permeability of 350 Darcies, all of which are in the range required for biomedical implant applications. We also demonstrate that the micron scale intra-strut porosities can be exploited to allow infiltration of bioactive materials using a novel bioactive silica-polymer composite, resulting in a metal-bioactive silica-polymer composite.
authors.affiliation: Department of Materials, Imperial College London, London SW7 2AZ, UK.
authors.forename: R
authors.initials: R
authors.lastname: Singh
authors.forename: P D
authors.initials: PD
authors.lastname: Lee
authors.forename: J R
authors.initials: JR
authors.lastname: Jones
authors.forename: G
authors.initials: G
authors.lastname: Poologasundarampillai
authors.forename: T
authors.initials: T
authors.lastname: Post
authors.forename: T C
authors.initials: TC
authors.lastname: Lindley
authors.forename: R J
authors.initials: RJ
authors.lastname: Dashwood
mesh_terms: D002152:Calorimetry, Differential Scanning; D002516:Ceramics / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D053761:Nanocomposites / Q000648:ultrastructure; D010316:Particle Size; D010539:Permeability; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry; D054457:Tissue Scaffolds / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D020099:Coated Materials, Biocompatible; D012822:Silicon Dioxide; D014025:Titanium