Characterization of Hydrogenated Dentin Components by Advanced <sup>1</sup>H Solid-State NMR Experiments

Abstract

Collecting information about molecular organisation on biological materials such as bone and dentine represents a major challenge in attaining a better understanding of their mechanical properties. To that end, solid state NMR (ssNMR) spectroscopy is an appropriate strategy to provide atomic structural details on these amorphous composite materials. However, species like water molecules and hydroxyl groups are usually observed through 1H magic angle spinning (MAS) ssNMR that suffers from poor resolution due to strong signal overlapping, making their identification difficult.This paper proposes a set of ssNMR experiments for 1H characterization of the main components of human dentin, based on homo- and hetero-nuclear dipolar couplings and composed mostly of fast 1D experiments. The 1H assignment is assisted by straightforward sample modifications: vacuum drying, deuterium exchange and demineralization. These experiments allow the hydrogen signal edition of dentin species like water molecules, HPO42- and OH- groups, depending on their localization (bound to the organic phase, linked to apatite or at the interface) and their dynamic behaviour. This ssNMR toolbox has the potential to provide important structural and dynamic information on chemical and physical modifications of biomaterials.