Molecular Dynamics Simulations and Structural Descriptors of Radioisotope Glass Vectors for In Situ Radiotherapy

Abstract

The low solubility (high durability) of yttrium aluminosilicate (YAS) glass is one of its most important properties for use in in situ radiotherapy. Simple parameters, such as silica or yttria content or network connectivity, are not sufficient to rationalize the dependence of the solubility on the glass composition observed experimentally. We performed classical molecular dynamics (MD) simulations of eight different YAS glasses of known solubility and analyzed the MD trajectories to identify specific structural features that are correlated and can be used to predict the solubility. We show that the (Si-)O-Si coordination number CN(SiOSi), the yttrium-yttrium clustering ratio R(YY), and the number of intratetrahedral O-Si-O bonds per yttrium atom N(intra) can be combined into a single structural descriptor s = f(CN(SiOSi),R(YY),N(intra)) with a high correlation with the solubility. The parameter s can thus be calculated from MD simulations and used to predict the solubility of YAS compositions, allowing one to adjust them to the range required by radiotherapy applications. For instance, its trend shows that high-silica- and low-yttria-content YAS glasses should be sufficiently durable for the radiotherapy application, although additional clinical considerations may set a lower limit to the yttria content.

Computational Modeling of Silicate Glasses: A Quantitative Structure-Property Relationship Perspective

“…In a recent work by Christie et al [54] the specific structural features of the glasses that control the solubility of a series of yttrium aluminosilicate glasses (parent glass composition: 17Y 2 O 3 -19Al 2 O 3 -64SiO 2 ) have been extracted from MD simulations and used to predict the solubility of these materials. In particular, a linear combination of the following descriptors showed a high correlation with the experimental solubility: (1) CN SiOSi , which is the average O-Si coordination number of oxygen atoms already coordinated to at least another silicon atom.…”

Effect of strontium inclusion on the bioactivity of phosphate-based glasses

“…Molecular dynamics (MD) simulations provide the atomic structure of the glass, as well as enabling computation of large-scale materials properties. We and others have previously used MD simulations to elucidate the connection between atomic structure and dissolution behaviour of a variety of silicate [20][21][22][23][24][25][26][27] and phosphate glasses [28][29][30] intended for implantation, including strontium-containing silicate glass [13,14]. However, there have been no simulations of Sr in phosphate glass.…”

Atomic structure of biodegradable Mg-based bulk metallic glass

“…We use very accurate first-principles computer simulations to investigate the atomic structure of two compositions of Mg-Zn-Ca glass, one of which (Mg 60 Zn 35 Ca 5 ) forms the passivating surface layer, and one of which (Mg 72 Zn 23 Ca 5 ) does not. Computer simulation has proved invaluable in complementing experimental investigations into glass structure, including in elucidating the structure of glasses used for implantation into the body [14][15][16][17][18].…”