Molecular dynamics simulations of bio-active phosphate-based glass surfaces

Ruiz‐Hernandez, Sergio E.; Ainsworth, Richard I.; Leeuw, Nora H. de

doi:10.1016/j.jnoncrysol.2016.06.004

Cited by 8 publications

(6 citation statements)

References 34 publications

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“…Once immersed in aqueous solution, the hydrated phosphate chains are released into solution, where there undergo hydrolysis. However, an initial pH decrease (from 7.4 ± 0.1 in day-0 to 7.0 ± 0.1 in day-7) was observed in this case (see Figure 4), which was suggested to be a result of phosphate anions in solution released into the media, potentially creating acidic species [67][68][69]. The dissolved phosphate chains broke down to orthophosphate ultimately via hydrolysis in solution [66], leading to saturation of the media and precipitate formation in static environment.…”

Section: Dissolution Properties Of Non-annealed Fibresmentioning

confidence: 78%

Effects of Fe2O3 addition and annealing on the mechanical and dissolution properties of MgO-and CaO-containing phosphate glass fibres for bio-applications

Tan¹,

Ahmed²,

Parsons³

et al. 2018

Biomedical Glasses

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This paper investigated the preparation of phosphate glass fibres (PGFs) in the following systems: i) 45P2O5-5B2O3-5Na2O-(29-x)CaO-16MgO-(x)Fe2O3 and ii) 45P2O5-5B2O3-5Na2O-24CaO-(21-x)MgO-(x)Fe2O3 (where x = 5, 8 and 11 mol%) for biomedical applications. Continuous fibres of 23 ± 1 μm diameter were prepared via a meltdraw spinning process. Compositions with higher Fe2O3 content and higher MgO/CaO ratio required higher melting temperature and longer heating time to achieve glass melts for fibre pulling. The effects of Fe2O3 addition and annealing treatment on mechanical properties and degradation behaviours were also investigated. Adding Fe2O3 was found to increase the tensile strength from 523 ± 63 (Ca-Fe5) to 680 ± 75 MPa (Ca-Fe11), improve the tensile modulus from72 ± 4 (Ca-Fe5) to 78 ± 3 GPa (Ca-Fe11) and decrease the degradation rate from 4.0 (Mg-Fe5) to 1.9 × 10−6 kg m−2 s−1 (Mg-Fe11). The annealing process reduced the fibre tensile strength by 46% (Ca-Fe5), increased the modulus by 19.6%(Ca-Fe8) and decreased the degradation rate by 89.5% (Mg-Fe11) in comparison to the corresponding as drawn fibres. Additionally, the annealing process also impeded the formation of precipitate shells and revealed coexistence of the precipitation and the pitting corrosion as fibre degradation behaviours.

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Section: Dissolution Properties Of Non-annealed Fibresmentioning

confidence: 78%

Effects of Fe2O3 addition and annealing on the mechanical and dissolution properties of MgO-and CaO-containing phosphate glass fibres for bio-applications

Tan¹,

Ahmed²,

Parsons³

et al. 2018

Biomedical Glasses

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“…In order to obtain the most detailed representation of its structural organisation, the structure of PGs is investigated using computer simulation. Molecular dynamics simulations have often been used to complement experimental data by highlighting different effects [26][27][28][29][30][31][32] which can be linked to the bioactivity such as the coordination environment of network formers, tendency of modifiers to form clusters, inhomogeneities and the existence of chain and ring nanostructures. Additionally, in some cases the acquisition of experimental measurements have proved to be complicated, time consuming or even unattainable [33,34].…”

Section: Introductionmentioning

confidence: 99%

Atomic-scale clustering inhibits the bioactivity of fluoridated phosphate glasses

Toure¹,

Mele²,

Christie³

2019

Biomedical Glasses

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Here, molecular dynamics simulations have been carried out on phosphate glasses to clarify the previously debated influence of fluoride on the bioactivity of these glasses. We developed a computationally advanced inter-atomic force field including polarisation effects of the fluorine and oxygen atoms. Structural characterisations of the simulated systems showed that fluoride ions exclusively bond to the calcium modifier cations creating clusters within the glass structure and therefore decreasing the bioactivity of fluoridated phosphate glasses, making them less suitable for biomedical applications.

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“…In the study by Ruiz Hernandez et al 11 , they are only formed at the interface z > 14 Å, with very few cations in the first coordination sphere, and at almost all times disconnected from the main phosphate network. Experimentally it is known that, once in solution, the phosphate rings are very stable 53,54 , but their very low concentrations observed in the MD, the lack of solvent in the model employed and no other information from higher levels of theory, make it difficult to predict their impact.…”

Section: Discussionmentioning

confidence: 95%

“…We have emphasised the role of computer simulation, usually molecular dynamics, in which our groups and others have played a leading role, and shown that it is an excellent technique for the characterisation of structural features at an atomic level. Three recent developments have been important drivers of research in this field: the development of a reliable interatomic force field for classical simulations 9 , the identification of modifier-phosphate bonding as the main structural motif controlling the dissolution 10 , and the simulation of the glass surface structure and properties 11 . Future work will need to make more quantitative predictions of dissolution rate, as well as consider the effect of solvent and solvated ions and molecules on the surface structure.…”

Section: Discussionmentioning

confidence: 99%

Structures and properties of phosphate-based bioactive glasses from computer simulation: a review

et al. 2017

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This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication.Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available.You can find more information about Accepted Manuscripts in the author guidelines.Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the ethical guidelines, outlined in our author and reviewer resource centre, still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. ture at the surface, and how this changes from that of the bulk.In the past few years, our groups and others have extensively used state-of-the-art highperformance computing methods, usually molecular dynamics (MD) simulations, to characterise the structure and properties of PBGs. In molecular dynamics, the individual atoms move due to the interatomic forces they experience from other atoms. Because the full three-dimensional structure of the material is available at all times, an MD trajectory contains a great deal of information from which the material's properties may be deduced. Our work has involved new methodological developments in the form of a new model of the phosphate interatomic forces 9 , and MD simulations have given new insight into the structural motifs which affect the dissolution which are not accessible to experimental methods 10 . Recently, the different properties of PBG at the surface of the glass, from where the dissolution takes place have been shown, which will also be important in unravelling the full connections between structure and dissolution 11 . Molecular dynamics methods for preparation of glassesA full review of molecular dynamics methods is beyond the scope of this paper; the reader is invited to turn to relevant books 12,13 . Broadly, there are two types of molecular dynamics used to prepare realistic glass models: classical and first-principles. In classical MD, the interatomic forces are represented by an empirical expression with a small number of parameters which are chosen to reproduce existing data on the material. This method has the advantage of being relatively easy to implement and computationally inexpensive, allowing for large models (typically ∼ 10 3 − 10 4 atoms) to be simulated over long timescales (typically ns). The disadvantage is that the accuracy of the simulation is limited by the accuracy of the approximations of the interatomic potential model. First-principles MD, by contrast, uses a quantum-mechanical expression for th...

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Molecular dynamics simulations of bio-active phosphate-based glass surfaces

Cited by 8 publications

References 34 publications

Effects of Fe2O3 addition and annealing on the mechanical and dissolution properties of MgO-and CaO-containing phosphate glass fibres for bio-applications

Effects of Fe2O3 addition and annealing on the mechanical and dissolution properties of MgO-and CaO-containing phosphate glass fibres for bio-applications

Atomic-scale clustering inhibits the bioactivity of fluoridated phosphate glasses

Structures and properties of phosphate-based bioactive glasses from computer simulation: a review

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