The Science & Technology
Cambridge - Monday 4th to
Wednesday 6th September 2017
Jamieson K. Christie
article posted 02 August 2017
Dr Jamieson Christie is a lecturer in the Department of Materials at Loughborough University, a post he took up in 2015. 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.
Bone repair ions in phosphate-based glass
Jamieson K. Christie*
Department of Materials, Loughborough University, Loughborough, LE11 3TU
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.
One of the main applications for amorphous biomaterials is in orthopaedics and bone repair. PBGs can be synthesised containing both magnesium, which is used in bone repair, and strontium,
which is used as a treatment for osteoporosis (low bone density).
Over the past few years, I and others have pioneered the understanding of phosphate glass structure through computer simulation, particularly identifying the structural motifs which affect
the glass dissolution rate when implanted [1-3], such as the bonding of network modifying atoms to phosphate chains (see Figure 1). The addition of therapeutically relevant substances
affect the structure and dissolution properties in ways which are sometimes difficult to determine experimentally, hence the extensive use of computer simulation.
In this talk, we present results from our recent investigations into the structures of magnesium and strontium when implanted in phosphate-based glasses. Calcium, magnesium and strontium
all belong to the same group of the periodic table, so share some similar properties. but their effect on the structure on the glass needs to be understood in order to optimise it for specific
applications. We have conducted classical molecular dynamics simulations of various Ca, Mg and Sr-containing  PBG compositions and present the local structures around the modifier ions,
as well as their bonding to the phosphate chains and the consequent effect on the dissolution rate.
 J. K. Christie, R. I. Ainsworth, D. Di Tommaso, N. H. de Leeuw, J. Phys. Chem. B 117, 10652 (2013)
 J. K. Christie, R. I. Ainsworth, N. H. de Leeuw, Biomaterials 35, 6164 (2014)
 J. K. Christie, R. I. Ainsworth, N. H. de Leeuw, J. Non-Cryst. Sols. 432, 31 (2016)
 J. K. Christie, N. H. de Leeuw, to appear, J. Mater. Sci.