Combined Experimental and Computational Approach toward the Structural Design of Borosilicate-Based Bioactive Glasses
Nicholas Stone‐Weiss, Henrik Bradtmüller, Mariagrazia Fortino, Marco Bertani, Randall E. Youngman, Alfonso Pedone, Hellmut Eckert, Ashutosh Goel
Abstract
Transitioning beyond a trial-and-error based approach for the compositional design of next-generation borosilicate-based bioactive glasses requires a fundamental understanding of the underlying compositional and structural drivers controlling their degradation and ion release in vitro and in vivo. Accordingly, the present work combines magic-angle spinning (MAS) NMR techniques, MD simulations, and DFT calculations based on GIPAW and PAW algorithms, to build a comprehensive model describing the short-to-medium-range structure of potentially bioactive glasses in the Na2O–P2O5–B2O3–SiO2 system over a broad compositional space. P2O5 preferentially tends to attract network modifier species, thus resulting in a repolymerization of the silicate network and a restructuring of the borate component. 11B{31P} and 31P{11B} dipolar recoupling experiments suggest that the ability of glasses to incorporate P2O5 without phase separation is related to the formation of P–O–B(IV) linkages integrated into the borosilicate glass network. An analogous approach is used for elucidating the local environments of the Na+ network modifiers. This work, along with future studies aimed at elucidating composition–structure–solubility/bioactivity relationships, will lay the foundation for the development of quantitative structure–property relationship (QSPR) models, thus representing a leap forward in the design of functional borosilicate bioactive glasses with controlled ionic release behavior.