IR-SPECTROSCOPIC INVESTIGATIONS OF NANOHYDROXYAPATITE POWDERS

Abstract

Recently, apatite minerals have gained much attention because of their biological importance. Hydroxyapatite is the major constituent of mammalian bones and tooth enamel. In addition to bone mineral and organic matrix, water is an abundant component of bone, accounting for up to 25% by weight. Attempts have been made to define and understand the role of water present in pore spaces of bones. Simultaneous derivative thermogravimetric analysis and variable temperature X-ray diffraction studies revealed the presence of structural water on carbonated apatite, a synthetic apatite used as a model of bone mineral that contains carbonate ions and is deficient in hydroxide, phosphate, and calcium ions. The unraveling of the ensemble of surface processes and phenomena actually occurring in vivo is still a challenge, but there is a general consensus in setting the causal sequence: (i) biomaterial surface structure, (ii) states of adsorbed water molecules, and (iii) states of adsorbed proteins, as one of the main factors ruling the fate of the interaction of the implant (then actually occurring through a hybrid synthetic/proteic interface) with cells.