Preparation and characterization of antibacterial P₂O5-CaO-Na₂O-Ag₂O glasses.

60P₂O₅-20CaO-(20-x) Na₂O-xAg₂O and 60P₂O₅-30CaO-(10-x) Na₂O-xAg₂O glasses, x = 0, 0.5,1, and 2 mol % were prepared using normal glass melting technique. The antibacterial activity of pressed disks of powdered glass (undoped and silver-doped glass) was investigated against S.aureus, P.aeruginosa, and E.coli micro-organisms using agar disk-diffusion assays at 37 °C for 24 h. The antibacterial activity was deduced from the inhibition zone diameter (IZD), zone of no bacterial growth, measured under the stated experimental conditions. The antibacterial activity increases with the increase in IZD and vice versa. Dissolution of glass in water at 37 °C, pH changes of water during glass dissolution, and concentrations of silver ions released from silver-doped glasses into water during their dissolution were determined. An increase in the concentration of silver ions released from silver-doped glasses into water was observed with increasing time of glass dissolution and with increasing Ag₂O content. The tested silver-free and silver-doped glasses demonstrated different antibacterial activity against the tested micro-organisms. For silver-free glasses, an increase in IZD was observed with the increase in the glass dissolution rate and with the decrease in pH of water. Also, the IZD showed an increase with increasing Ag₂O content of silver-doped glasses.