Publications (4) View all
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Article: Short-term in vitro responses of human peripheral blood monocytes to ferritic stainless steel fiber networks.
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ABSTRACT: Beneficial effects on bone-implant bonding may accrue from ferromagnetic fiber networks on implants which can deform in vivo inducing controlled levels of mechanical strain directly in growing bone. This approach requires ferromagnetic fibers that can be implanted in vivo without stimulating undue inflammatory cell responses or cytotoxicity. This study examines the short-term in vitro responses, including attachment, viability, and inflammatory stimulation, of human peripheral blood monocytes to 444 ferritic stainless steel fiber networks. Two types of 444 networks, differing in fiber cross section and thus surface area, were considered alongside austenitic stainless steel fiber networks, made of 316L, a widely established implant material. Similar high percent seeding efficiencies were measured by CyQuant® on all fiber networks after 48 h of cell culture. Extensive cell attachment was confirmed by fluorescence and scanning electron microscopy, which showed round monocytes attached at various depths into the fiber networks. Medium concentrations of lactate dehydrogenase (LDH) and tumor necrosis factor alpha (TNF-α) were determined as indicators of viability and inflammatory responses, respectively. Percent LDH concentrations were similar for both 444 fiber networks at all time points, whereas significantly lower than those of 316L control networks at 24 h. All networks elicited low-level secretions of TNF-α, which were significantly lower than that of the positive control wells containing zymosan. Collectively, the results indicate that 444 networks produce comparable responses to medical implant grade 316L networks and are able to support human peripheral blood monocytes in short-term in vitro cultures without inducing significant inflammatory or cytotoxic effects. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.Journal of Biomedical Materials Research Part A 10/2012; · 2.63 Impact Factor -
Article: Osteoblast and monocyte responses to 444 ferritic stainless steel intended for a magneto-mechanically actuated fibrous scaffold.
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ABSTRACT: The rationale behind this work is to design an implant device, based on a ferromagnetic material, with the potential to deform in vivo promoting osseointegration through the growth of a healthy periprosthetic bone structure. One of the primary requirements for such a device is that the material should be non-inflammatory and non-cytotoxic. In the study described here, we assessed the short-term cellular response to 444 ferritic stainless steel; a steel, with a very low interstitial content and a small amount of strong carbide-forming elements to enhance intergranular corrosion resistance. Two different human cell types were used: (i) foetal osteoblasts and (ii) monocytes. Austenitic stainless steel 316L, currently utilised in many commercially available implant designs, and tissue culture plastic were used as the control surfaces. Cell viability, proliferation and alkaline phosphatase activity were measured. In addition, cells were stained with alizarin red and fluorescently-labelled phalloidin and examined using light, fluorescence and scanning electron microscopy. Results showed that the osteoblast cells exhibited a very similar degree of attachment, growth and osteogenic differentiation on all surfaces. Measurement of lactate dehydrogenase activity and tumour necrosis factor alpha protein released from human monocytes indicated that 444 stainless steel did not cause cytotoxic effects or any significant inflammatory response. Collectively, the results suggest that 444 ferritic stainless steel has the potential to be used in advanced bone implant designs.Biomaterials 06/2011; 32(29):6883-92. · 7.40 Impact Factor -
Article: Carbon nanotubes for orthopaedic implants
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ABSTRACT: The physical and biological limitations of current orthopaedic implant materials are a major challenge for bone tissue engineering. Nanotechnology has introduced new materials and methods for meeting this challenge. The application of nanotechnology to engineering new bone substitutes finds a model in the nanoscale components of natural bone tissue. Carbon nanotubes are a macromolecular form of carbon with exceptional properties and similar morphology and dimensions to the nanoscale collagen fibers of natural bone tissue. Carbon nanotubes have been used in two main areas of bone tissue engineering: for structural and electrical enhancement of polymer and ceramic composites and for nanostructured coatings to improve the bioactivity of implant surfaces. By incorporating carbon nanotubes into the design and engineering of bone tissue substitutes, researchers have attempted to overcome limitations in the structural and biological compatibility of traditional orthopaedic implant materials.International Journal of Material Forming 01/2008; 1(2):127-133. -
Article: Templated growth of calcium phosphate on tyrosine derived microtubules and their biocompatibility.
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ABSTRACT: Microtubular structures were self-assembled in aqueous media from a newly synthesized bolaamphiphile, bis(N-alpha-amido-tyrosyl-tyrosyl-tyrosine)-1,5-pentane dicarboxylate. In order to increase the biocompatibility of the microtubules, they were functionalized with the peptide sequence GRGDSP. Further, calcium phosphate nanocrystals were grown on the microtubules. In some cases, collagen was added in order to mimic the components of natural bone tissue. The biomaterials obtained were characterized via transmission electron microscopy (TEM), atomic force microscopy (AFM), IR, and energy dispersive X-ray spectroscopy (EDX) analyses. The biocompatibility of the calcium phosphate-coated microtubules was studied by conducting in vitro cell-attachment, cell-proliferation and cytotoxicity studies using mouse embryonic fibroblast (MEF) cells. The studies revealed that the biomaterials were found to be non-toxic and biocompatible. The functionalized tubular assemblies coated with calcium phosphate nanocrystals mimic the nanoscale composition of natural bone and may potentially support bone in-growth and osseointegration when used in orthopaedic or dental applications.Colloids and Surfaces B Biointerfaces 12/2007; 60(2):158-66. · 3.46 Impact Factor
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