Cambridge 7th to 9th September
article posted 22 Mar 2015
Dr Jamieson Christie is a lecturer in the Department of Materials at Loughborough University, a post he took up in 2015 after research positions at University College London and The Abdus Salam International Centre for Theoretical Physics in Trieste, and a PhD at the University of Cambridge.
His research interests are in the computer simulation of glass, particularly biomedically relevant compositions. Much of a particular composition's suitability for biomedical implantation can be understood from a characterization of its atomic structure and Jamie has used a range of computational techniques to improve our understanding of these connections.
Understanding the solubility of bioactive phosphate-based glass
Jamieson K. Christie1*, Richard I. Ainsworth2,
Devis Di Tommaso3, Nora H. de Leeuw4
Phosphate-based glasses (PBG) have wide application as biomaterials because they
dissolve when implanted into the body, with a composition-dependent dissolution rate
that varies over several orders of magnitude. They can be synthesised containing
different substances or materials, making them useful for controlled delivery of
therapeutically relevant substances. In order to optimise PBGs for these applications,
it is vital to understand the dependence of their dissolution rate on the glass composition
and structure. We have used molecular dynamics (MD) simulations to understand these
relationships at the atomistic level.
Classical MD simulations  with a polarizable force field  show that for
biomedically relevant compositions (<50 mol % P2
and some Na2
O and CaO)
where the dissolution rate substantially decreases with increasing CaO content,
Ca binds together more phosphate chains (3.9) than Na does (3.2), strengthening
the glass network and making it less prone to dissolution.
The inclusion of therapeutic ions alters the glass structure and properties in non-trivial
ways which are accessible to simulation. First-principles MD has predicted that
fluorinated PBGs do not have the same inhomogeneities as fluorinated silicate glass,
opening up their use as biomaterials for dental treatment . Silver is an antibiotic,
and we have suggested that Ag/Na substitution will not affect the biological activity
of the glass . We have characterised the strontium environment in PBGs  and its
(negligible) effect on the glass's suitability for biomedicine.
1 Department of Materials, Loughborough University
2 Department of Chemistry and Biochemistry, University of California, San Diego
3 School of Biological and Chemical Sciences, Queen Mary, University of London
4 Department of Chemistry, University of Cardiff