Development and characterization of silver-doped sol-gel-derived borate glasses with anti-bacterial activity

Borate glasses have gained attention in wound healing applications attributable to their lower chemical durability compared to silicate glasses, allowing for increased degradation rates and potentially accelerated benefits in the healing process. Recently, the sol-gel process was used to fabricate borate glasses with high specific surface areas (SSAs) leading to rapid dissolution and high reactivity when compared to their melt-quench derived equivalents. In this study, silver doped sol-gel derived borate glasses (AgBGs) were developed to impart anti-bacterial properties, thus potentially offering treatment for chronic and infected wounds. In order to optimize glass composition, the sol-gel processing route was adapted to generate two different AgBG compositional ranges; (46)B2O3-(27)CaO-(24-X)Na2O-(3)P2O5-(X)Ag2O where X = 0, 0.15, 0.5 and 1 (mol%) and (60)B2O3-(36)CaO-(4-X)P2O5-(X)Ag2O where X = 0, 0.3, 0.5 and 1 (mol%). It was demonstrated that the latter, sodium-free formulation resulted in enhanced silver incorporation with high SSA (237–300 m2/g) and small pore width (31–44 Å) values. XRD and ATR-FTIR were used to verify the amorphous nature of the glasses and the presence of BO3 and BO4 units as the glass network former, respectively. Extent of silver ion release from the dissolution of AgBG in deionized water verified its dependency on the processing route and glass composition. Additionally, the anti-bacterial activity of AgBGs against Escherichia coli and Staphylococcus aureus was correlated with silver ion release. To the best of our knowledge, this is the first report demonstrating the potential use of anti-bacterial sol-gel derived AgBGs for potential wound healing applications.