Nanocrystalline apatites are major constituents of hard tissues, and attempts are made worldwide to prepareudsynthetic analogs. However the impact of synthesis/ postsynthesis parameters is often disregarded. Based on anudupdated knowledge on such compounds, we inspected the effects of synthesis parameters (maturation time, temperature,pH, nature of counter-ions) and post-treatmentsud(re-immersion in aqueous media, thermal treatment) on physicochemical characteristics. Great modifications wereudnoticed during the 3 first days of maturation, where audprogressive evolution of the apatite phase (localized in theudcore 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-dryingudallowed to preserve a high surface reactivity, althoughudfurther evolutions were noticed after re-immersion. Effectsudof a thermal treatment of dried samples were unveiled, suggesting a denaturation of the hydrated layer on theudnanocrystals. This work underlines the necessity of a goodudcontrol of synthesis/postsynthesis parameters for the production of biomimetic apatites.
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