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Mechanical properties, structure, bioactivity and cytotoxicity of bioactive Na-Ca-Si-PO-(N) glasses

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Show simple item record Mabrouk, Assia Bachar, Ahmed Atbir, Ali Follet, Claudine Mercier, Cyrille Tricoteaux, Arnaud Leriche, Anne Hampshire, Stuart 2018-07-16T10:19:58Z 2018
dc.description peer-reviewed en_US
dc.description.abstract Bioactive glasses are able to bond to bone through formation of carbonated hydroxyapatite in body fluids. However, because of their poor strength their use is restricted to non-load-bearing applications. The effects of nitrogen addition on the physical and mechanical properties and structure of bioactive oxynitride glasses in the system Na–Ca–Si–P–O–N have been studied. Glasses with compositions (mol.%): 29Na2O–13.5CaO–2.5P2O5–(55 −3x)SiO2–xSi3N4 (x is the no. of moles of Si3N4) were synthesised with up to 1.5 at% P and 4.1 at% N. A novel 3-step process was used for addition of P and N and this proved successful in minimising weight losses and producing homogeneous glasses with such high SiO2 contents. The substitution of 4.12 at% N for oxygen results in linear increases in density (1.6%), glass transition temperature (6%), hardness (18%) and Young’s modulus (74%). Vickers Indentation Fracture (VIF) resistance (Kifr) was calculated from various relationships depending on the load, indent diagonal, crack lengths and Young’s modulus to hardness (E/H) ratio. Firstly, Meyer’s index n is calculated from the slope of the logarithmic plot of load versus indent diagonal. Then by comparing the experimental slopes of the logarithmic plots of crack lengths versus load it is concluded that the cracking mode is Radial Median type. The substitution of 4.12 at% N for oxygen results in an increase in Kifr of 40%. These increases in properties are consistent with the incorporation of N into the glass structure in three-fold coordination with silicon which results in extra cross-linking of the glass network. The structure of these bioactive oxynitride glasses was investigated by solid state nuclear magnetic resonance (MAS NMR) of 31P and 29Si. The structure reveals that all the N atoms are bonded to Si atoms with the formation of SiO3N, SiO2N2 and Q4 structural units with extra bridging anions at the expense of Q3 units. The bioactivity of the glasses has been evaluated by soaking them in simulated body fluid (SBF) and results confirm that all these oxynitride glasses are bioactive. Cytotoxicity tests based on different concentrations of these bioactive glass powders in a cell growth environment have also shown that they are not cytotoxic. en_US
dc.language.iso eng en_US
dc.publisher Elsevier en_US
dc.relation.ispartofseries Journal of the Mechanical Behavior of Biomedical Materials;86, pp. 284-293
dc.rights This is the author’s version of a work that was accepted for publication in Journal of the Mechanical Behavior of Biomedical Materials . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published inMechanical Behavior of Biomedical Materials, 2018, 86, pp. 284-293, en_US
dc.subject bioactive glass en_US
dc.subject oxynitride glass en_US
dc.subject mechanical properties en_US
dc.subject fracture resistance en_US
dc.subject thermal properties en_US
dc.subject glass structure en_US
dc.title Mechanical properties, structure, bioactivity and cytotoxicity of bioactive Na-Ca-Si-PO-(N) glasses en_US
dc.type info:eu-repo/semantics/article en_US
dc.type.supercollection all_ul_research en_US
dc.type.supercollection ul_published_reviewed en_US
dc.identifier.doi 10.1016/j.jmbbm.2018.06.023 2020-06-22
dc.embargo.terms 2020-06-22 en_US
dc.rights.accessrights info:eu-repo/semantics/openAccess en_US

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