Advanced Solid State NMR Techniques for the Investigation of the Organic-Mineral Interfaces in Biomaterials
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1236-SS08-02
Advanced Solid State NMR Techniques for the Investigation of the Organic-Mineral Interfaces in Biomaterials Danielle Laurencin,1 Gilles Guerrero,1 Julien Amalric,1 Christian Bonhomme,2 Christel Gervais,2 Mark E. Smith,3 P. Hubert Mutin1 1
Institut Charles Gerhardt de Montpellier, UMR 5253, CNRS - UM2 - UM1 - ENSCM, CC1701, Place Eugène Bataillon, 34095 Montpellier cedex 5, FRANCE 2 Laboratoire de Chimie de la Matière Condensée de Paris, UMR 7574, UPMC Université Paris 06, Collège de France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, FRANCE 3 Department of Physics, University of Warwick, Coventry, CV4 7AL, UK ABSTRACT High resolution solid state NMR experiments were carried out on several compounds, to see how this technique can now be used to investigate in detail the surface structure of different biomaterials. First, because the surface of titanium implants can be functionalized by phosphonic acids, for instance to prevent bacterial adhesion, 17O NMR experiments were performed on model TiO2 surfaces functionalized by 17O enriched phosphonic acids, to look at the mode of grafting of these coupling agents. Results bring clear evidence of the formation of Ti-O-P bridges and of the presence of residual P=O and P-OH groups. Second, given that calcium phosphates are widely present in biological hard tissues and synthetic biomaterials, 43Ca correlation experiments were performed on 43Ca enriched materials (hydroxyapatite and calcium benzoate), to see how the proximities between this nucleus and neighbouring atoms can be analyzed. Results show that both Ca...C and Ca...H proximities can be evidenced, and could thus help elucidate interface structures. All in all, these studies should pave the way to future investigations of biomaterials, and in particular of the structure of organic-inorganic interfaces. INTRODUCTION Over the past 20 years, extensive research has been carried out in biomaterials science in order to improve the in vivo performance of implants and drug-delivery devices. In particular, much effort has been made to better control the surface morphology and chemistry of biomaterials, because of their known impact on the biological response [1], and the functionalization of materials by active molecules such as drugs or antibacterial species has thus been widely investigated [2,3]. The in vivo properties of functionalized biomaterials, notably the durability of the functionalization, will strongly depend upon the nature of the bonds between the active molecules and the surface, and of their reactivity in physiological conditions. Thus, it appears crucial to characterize in detail the mode of binding of active molecules at the surface of biomaterials, in order to rationalize and improve their properties. Since solid state NMR is a site-specific probe, it is a method of choice to analyze the structure of biointerfaces. Here, we will show how recent advances in the technique can be used to investigate in detail the structure of model synthetic compounds of biological interest.
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