Structure and surface properties of the apatite growth on gel glasses

摘要

The development of high surface area and adequate porosity have been claimed as responsible for the high bioactivity exhibited by sol-gel glasses when immersed in a Simulated Body Fluid (SBF). However, the fast growth of a phosphate-rich layer on the surface of bioactive materials when exposed to physiological conditions, confers this layer the key role in determining the nature of the biomaterial/bone interface. The objective of this study has been to evaluate the surface properties of the phosphate layer developed on the surface of a SiO_2-CaO (CaO = 20 molpercent) bioactive gel-glass by immersion into SBF. The growing process of the calcium phosphate layer has been monitored by SEM/EDS, TEM/ED and XPS. A calcium phosphate layer started to form very rapidly, covering most of the glass surface at only 3 h. Silicon is detected by XPS in the sample fully covered by calcium phosphate, which sugggest that it is present during the whole crystallisation process at the phosphate/solution interface.