The structure and properties of silver-doped phosphate-based glasses

An undoped and two silver-doped (0, 3 and 5 mol% Ag) phosphate glass compositions were investigated for their structure and properties. These compositions had in a previous study been investigated for their antimicrobial properties, and were found to be extremely potent at inhibiting the micro-organisms tested. Thermal, X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and X-ray absorption Near Edge Structure (XANES) studies were used to elucidate the structure of the compositions investigated, whilst degradation and ion release studies were conducted to investigate their properties. No significant differences were found between the T _g values of the silver containing glasses, while XRD analysis revealed the presence of a NaCa(PO₃)₃ phase. NMR showed the dominance of Q² species, and XANES studies revealed the oxidation state of silver to be in the +1 form. No correlation was seen between the degradation and cation release profiles observed, and the P₃O ₉ ³⁻ anion was the highest released anionic species, which correlated well with the XRD and NMR studies. Overall, it was ascertained that using Ag₂SO₄ as a precursor, and producing compositions containing 3 and 5 mol% Ag, the levels of silver ions released were within the acceptable cyto/biocompatible range.