We investigate high-modulus degradable materials intended to replace metals in biomedical applications.These are typically composites comprising a polylactide(PLA)matrix reinforced with phosphate glass fibres,which pr...We investigate high-modulus degradable materials intended to replace metals in biomedical applications.These are typically composites comprising a polylactide(PLA)matrix reinforced with phosphate glass fibres,which provide reinforcement similar to E-glass but are entirely degradable in water to produce,principally,calcium phosphate.We have made composites using a variety of fibre architectures,from non-woven random mats to unidirectional fibre tapes.Flexural properties in the region of 30 GPa modulus and 350 MPa strength have been achieved-directly comparable to quoted values for human cortical bone.In collaboration with other groups we have begun to consider the development of foamed systems with structures mimicking cancellous bone and this has shown significant promise.The fibres in these foamed structures provide improved creep resistance and reinforcement of the pore walls.To date the materials have exhibited excellent cellular responses in vitro and further studies are due to include consideration of the surface character of the materials and the influence of this on cell interaction, both with the composites and the glass fibres themselves,which show promise as a standalone porous scaffold.展开更多
A novel approach was developed to reduce the corrosion rate of magnesium(Mg)metal,utilising titanate coatings.Magnetron sputtering was used to deposit ca.500 nm titanium(Ti)coatings onto pure Mg discs,followed by hydr...A novel approach was developed to reduce the corrosion rate of magnesium(Mg)metal,utilising titanate coatings.Magnetron sputtering was used to deposit ca.500 nm titanium(Ti)coatings onto pure Mg discs,followed by hydrothermal conversion and ion exchange reactions to produce sodium and calcium titanate coatings.SEM confirmed the characteristic nanoporous structure of sodium and calcium titanate,with thicknesses ranging from ca.0.8 to 1.4μm.XPS analysis confirmed the presence of Ti^(4+)-O,Na-O,and Ca-O bonding,whilst Raman spectroscopy demonstrated characteristic vibrational modes(such as TiO 6 octahedral vibrations)of the sodium and calcium titanate perovskite structure.Furthermore,corrosion studies through potentiodynamic polarisation measurements demonstrated the NB/NH CaTC samples to be superior in reducing Mg degradation,compared to other samples tested,through an increase in E_(corr)from-1.49 to-1.33 V,and the reduction in corrosion current density,i corr,from 0.31 to 0.06 mA/cm^(2)for Mg and NB/NH CaTC samples,respectively.There was a clear trend noted for the NB/NH samples,which showed an increase in E corr to more positive values in the following order:Mg<Ti coated<NaTC<CaTC.These nanoporous titanate coatings have potential to be applied onto degradable plates for bone fracture fixation,or other orthopaedic applications.展开更多
文摘We investigate high-modulus degradable materials intended to replace metals in biomedical applications.These are typically composites comprising a polylactide(PLA)matrix reinforced with phosphate glass fibres,which provide reinforcement similar to E-glass but are entirely degradable in water to produce,principally,calcium phosphate.We have made composites using a variety of fibre architectures,from non-woven random mats to unidirectional fibre tapes.Flexural properties in the region of 30 GPa modulus and 350 MPa strength have been achieved-directly comparable to quoted values for human cortical bone.In collaboration with other groups we have begun to consider the development of foamed systems with structures mimicking cancellous bone and this has shown significant promise.The fibres in these foamed structures provide improved creep resistance and reinforcement of the pore walls.To date the materials have exhibited excellent cellular responses in vitro and further studies are due to include consideration of the surface character of the materials and the influence of this on cell interaction, both with the composites and the glass fibres themselves,which show promise as a standalone porous scaffold.
基金This work was supported by the Engineering and Physi-cal Sciences Research Council[grant numbers EP/K029592/1,EP/L022494/1].
文摘A novel approach was developed to reduce the corrosion rate of magnesium(Mg)metal,utilising titanate coatings.Magnetron sputtering was used to deposit ca.500 nm titanium(Ti)coatings onto pure Mg discs,followed by hydrothermal conversion and ion exchange reactions to produce sodium and calcium titanate coatings.SEM confirmed the characteristic nanoporous structure of sodium and calcium titanate,with thicknesses ranging from ca.0.8 to 1.4μm.XPS analysis confirmed the presence of Ti^(4+)-O,Na-O,and Ca-O bonding,whilst Raman spectroscopy demonstrated characteristic vibrational modes(such as TiO 6 octahedral vibrations)of the sodium and calcium titanate perovskite structure.Furthermore,corrosion studies through potentiodynamic polarisation measurements demonstrated the NB/NH CaTC samples to be superior in reducing Mg degradation,compared to other samples tested,through an increase in E_(corr)from-1.49 to-1.33 V,and the reduction in corrosion current density,i corr,from 0.31 to 0.06 mA/cm^(2)for Mg and NB/NH CaTC samples,respectively.There was a clear trend noted for the NB/NH samples,which showed an increase in E corr to more positive values in the following order:Mg<Ti coated<NaTC<CaTC.These nanoporous titanate coatings have potential to be applied onto degradable plates for bone fracture fixation,or other orthopaedic applications.
