Probing local environments in calcium pyrophosphate-based glasses for bone regeneration combining advanced characterization methods and computational modelling

Reference Presenter Authors
02-006 Christel Gervais Gervais, C.(university Pierre et Marie Curie); Bonhomme, C.(university Pierre et Marie Curie); Petit, I.(university Pierre et Marie Curie); Sassoye, C.(university Pierre et Marie Curie); Laurencin, D.(Institut Charles Gerhardt Montpellier); Combes, C.(ENSIACET); Mayen, L.(ENSIACET); Soulie, J.(ENSIACET); Rimsza, J.(University of North Texas); Du, J.(University of North Texas);
In the context of bone regeneration in orthopedic oral and maxillofacial surgery applications, new calcium pyrophosphate-based glasses elaborated by soft chemistry are developed [1]. These new generation glasses containing mainly pyrophosphate and orthophosphate entities and calcium cations are believed to exhibit tunable resorption kinetics, pH and biological controlled degradation profiles and economical and scalable processability that would overcome the current bioactive glass performance limitations.
A combined experimental-computational approach is used to determine in detail the structure of these glasses. Solid-state NMR experiments allow to gain an insight into the nature of phosphate entities (ortho/pyro), their precise ratio, their protonation state, and the relative proximity between the ortho- and pyrophosphate entities. In parallel, the topology of the glasses in terms of medium range distances is determined thanks to the analysis of Pair Distribution Fonctions (PDF). Glass models are then elaborated using ab initio molecular dynamics (MD). The structures are relaxed using Density Functional Theory (DFT) and for each optimized structure, the PDF is calculated, as well as the NMR parameters. A second step of optimization of the structure is performed by reverse Monte Carlo modeling to minimize the differences between the experimental and the calculated PDF data. The validity of the models is finally evaluated by comparing the calculated NMR parameters and the PDF to the experimental results.
The final objective of this advanced combined characterization methods and computational modeling is to determine correlations between the synthesis parameters and the nature, structure and morphologies of materials

[1] Soulié J., Gras P., Marsan O., Laurencin D., Rey C., Combes C., Development of a new family of monolithic calcium (pyro)phosphate glasses by soft chemistry, Acta Biomat., 41 (2016) 320–327
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