posted on 2016-02-03, 00:00authored byLinda Pastero, Dino Aquilano
Calcium
hydroxyapatite, HAp hereinafter, Ca5(OH)(PO4)3, the main component of vertebrate bones and
teeth, plays a strategic role mainly in biomedical applications because
of its bioactivity, biocompatibility, and slow-degradation rate. It
is a critical bioceramic material due to its properties of osteo-conduction,
-integration, and -induction. Moreover, HAp has a role in catalysis,
agricultural and pharmaceutical products, protein chromatography,
and water and soil treatment as well. The bulk of investigations about
HAp concerns nanosized crystals, owing to the difficulties encountered
when growing large laboratory crystals. Then, deep information about
surface and even bulk properties are unavoidably lacking. In this
paper, we investigate the relationship between the HAp polymorphism
and its growth morphology both from the experimental and theoretical
point of view. The micron-sized and well grown crystals we obtained
are exploitable for morphological investigations, in order to better
understand detailed surface properties determining the crystal reactivity.
Further, a clean and effective HAp method of chemical synthesis is
proposed, and the involved crystal-growth mechanisms are extensively
investigated as well. Finally, the unexpected synergic effect between
the low supersaturation of the HAp solution and the templating effect
of the monetite (CaHPO4) crystal, used as precursors, is
recognized.