Ab initio molecular dynamics simulations of structural changes associated with the incorporation of fluorine in bioactive phosphate glasses

Jamieson K Christie,Richard I Ainsworth,Nora H De Leeuw

doi:10.1016/j.biomaterials.2014.04.032

Jamieson K Christie, Richard I Ainsworth + Show 1 more

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https://doi.org/10.1016/j.biomaterials.2014.04.032

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Journal: Biomaterials	Publication Date: May 5, 2014
Citations: 40	License type: cc-by

Affiliation: University College London

Abstract

Phosphate-based bioactive glasses containing fluoride ions offer the potential of a biomaterial which combines the bioactive properties of the phosphate glass and the protection from dental caries by fluoride. We conduct accurate first-principles molecular dynamics simulations of two compositions of fluorinated phosphate-based glass to assess its suitability as a biomaterial. There is a substantial amount of F–P bonding and as a result the glass network will be structurally homogeneous on medium-range length scales, without the inhomogeneities which reduce the bioactivity of other fluorinated bioactive glasses. We observe a decrease in the network connectivity with increasing F content, caused by the replacement of bridging oxygen atoms by non-bridging fluorine atoms, but this decrease is small and can be opposed by an increase in the phosphate content. We conclude that the structural changes caused by the incorporation of fluoride into phosphate-based glasses will not adversely affect their bioactivity, suggesting that fluorinated phosphate glasses offer a superior alternative to their silicate-based counterparts.

Highlights

Phosphate-based glasses [1] are increasingly used as biomaterials for implants in the body, owing to several valuable properties
The aim of this work is to characterise the atomic structure of fluorinated phosphate-based glasses, and the likely effect of the inclusion of fluorine on their bioactivity
In a fully connected phosphate glass, three of the oxygen of each PO4 group are bridging oxygen (BO) atoms which are bonded to another PO4 tetrahedron, whilst the fourth is a terminal oxygen (TO) atom, double-bonded to the phosphorus atom

Summary

Introduction

Phosphate-based glasses [1] are increasingly used as biomaterials for implants in the body, owing to several valuable properties. Certain glass compositions are bioactive, that is, they react chemically when placed in a physiological environment These glasses dissolve completely in aqueous environments, as found in the body, with a dissolution rate that varies over several orders of magnitude, dependent on composition [1,2]. The addition of dopants and changes in composition allow for the possibility of tuning the dissolution rate to make the glass suited for a specific application They have been less widely used clinically than other biomaterials [8], the increased solubility of phosphate-based glasses makes them eminently suitable for use as bioactive degradable materials, where the biomaterials or their dissolution products play an active role in tissue engineering

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