Biomimetic apatite-based biomaterials: on the critical impact of synthesis and post-synthesis parameters
Résumé
Nanocrystalline apatites are major constituents of hard tissues, and attempts are made worldwide to prepare
synthetic analogs. However the impact of synthesis/ postsynthesis parameters is often disregarded. Based on an
updated knowledge on such compounds, we inspected the effects of synthesis parameters (maturation time, temperature,pH, nature of counter-ions) and post-treatments
(re-immersion in aqueous media, thermal treatment) on physicochemical characteristics. Great modifications were
noticed during the 3 first days of maturation, where a
progressive evolution of the apatite phase (localized in the
core of the nanocrystals) toward stoichiometry was observed at the expense of the non-apatitic surface layer which progressively disappears. Similar trends were also evidenced for maturation run under increasing temperatures, studied here in the range 20–100 °C. pH impacted more specifically the chemical composition. The nature of the counter-ion in the starting phosphate salt influenced composition and nonstoichiometry, depending on its (in)ability to be incorporated in the lattice. Freeze-drying
allowed to preserve a high surface reactivity, although
further evolutions were noticed after re-immersion. Effects
of a thermal treatment of dried samples were unveiled, suggesting a denaturation of the hydrated layer on the
nanocrystals. This work underlines the necessity of a good
control of synthesis/postsynthesis parameters for the production of biomimetic apatites.
Domaines
Matériaux
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