Silver containing bioactive glasses prepared by molten salt ion-exchange

Bioactive glasses containing silver on their surface were produced by ion-exchange from dilute silver nitrate melts. This technique allowed introducing Ag+ ions only on the surface of the base glass while maintaining its bioactivity. The ion-exchanged glasses were characterized by means of X-Ray diffraction, SEM observations and compositional analysis (EDS). The control of the Ag+ content on the surface, as well as its diffusion profile throughout the ion-exchanged layer, was obtained by a careful choice of the ion-exchange parameters (temperature, time and silver concentration in the molten bath). A very good repeatability in the diffusion profile and in the silver concentration throughout the ion-exchanged layer was achieved. In vitro tests were performed on the ion-exchanged samples in order to verify their bioactive behavior (soaking in a simulated body fluid). On the soaked samples, the precipitation of a hydroxycarbonate apatite layer (HCAp) was investigated. The amount of released Ag+ into simulated body fluid from the exchanged glass was detected by atomic absorption spectroscopy with heated graphite furnace (GFAAS).