Crystallographic Aspects Regarding the Insertion of Ag+ Ions into a Hydroxyapatite Structure

• Autor(a) principal: Santos,Ivory Marcos Gomes dos
• Data de Publicação: 2015
• Outros Autores: Barbosa,Larissa Souza Noel Simas, Resende,Cristiane Xavier, Soares,Glória de Almeida, Santos,Euler Araujo dos
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Materials research (São Carlos. Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000400881
• topic: hydroxyapatite; silver; doping; carbonate; diffusion

The objective of this study was to evaluate how silver can be inserted into hydroxyapatite (HA) via two distinct processes: co-doping with CO32- via precipitation in an aqueous medium and immersion of preformed HA crystals into Ag+ solutions. It was concluded that although Ag+ and Ca2+ have different radii, the accommodation of Ag+ ions in the Ca2+ sites of the hydroxyapatite lattice can be explained by the models proposed for inserting monovalent ions such as Na+. In this case, because Ag+ ions are larger than Ca2+ ions and have a different charge, the Ag+ ions are stabilized in the HA structure by co-substitution with CO32- ions in both the A- and B-type sites. This simultaneous insertion of Ag+ and CO32- appears to thermally stabilize the HA phase because no phase transformation is observed after calcination. In addition, the doping of HA with Ag+ ions can clearly occur via two routes: co-precipitation in the presence of these ions or diffusion in preformed hydroxyapatite crystals. This result appears to indicate the possibility of doping HA with Ag+ using less complex routes at ambient temperature and with prefabricated implants or biomaterials, which reduces the costs of producing devices with antibacterial effects.