In vitro Chemical Reactivity of Doped Bioactive Glasses: an Original Approach by Solid-State NMR Spectroscopy

A study was conducted to investigate and determine the local structure of bioactive glasses before and after in vitro assays in simulated body fluid (SBF). 29Silicon and and 31P magic angle spinning (MAS)-NMR was used to characterize the local environment and determine the influence of doping elements on the chemical reactivity of glasses and the formation of hydroxyapatite. Transparent and bubble-free glasses were prepared for all compositions and ground using a milling machine and sieved to obtain particles with a size distribution ranging from 40-63 μm. Most of the 29Si MAS-NMR spectra were decomposed into two individual components. It was observed that most of the 31P MAS-NMR spectra presented a symmetric peak with a chemical shift range of 7.3-8.5 ppm. It was also observed that the 31P MAS-NMR spectra evolved with the immersion time in SBF solution in the same way as the 29Si spectra.