THE ROLE OF NIOBIUM IONS IN CALCIUM PHOSPHATE INVERT GLASSES FOR BONE REGENERATION

Abstract

Phosphate invert glasses (PIGs) containing niobium were prepared by a conventional melt-quenching method and the structures and chemical durability of the glasses and osteoblast-like cell responses to them were examined. Raman and solid state P NMR spectra of the glasses demonstrated that two types of niobate groups, NbO4 and NbO6 units, were contained in the glasses and prepared to combine to pyrophosphate structure than orthophosphate one. The chemical durability in Tris-HCl solution was increased with the increase in the niobium content in the glasses, since niobium replaced to phosphorus and contributed to the formation of P-O-Nb and Nb-O-Nb bonds, which are stronger than P-O-P bond. The niobium ions released from the glasses enhanced the differentiation and mineralization of the cells, rather than the initial adhesion and proliferation. The upregulation of these cell functions by the niobium ions possessed doze-dependence; the medium containing 1 x 10 M of the ions exhibited the highest levels of the cell functions. (Received Jan. 29, 2016; Accepted Feb. 27, 2016)