Characterisation of antibacterial copper releasing degradable phosphate glass fibres

Phosphate-based glass fibres (PGF) of the general formula Na2O–CaO–P2O5 are degradable in an aqueous environment, and therefore can function as antibacterial delivery systems through the inclusion of ions such as copper. In this study, PGF with varying amounts of copper oxide (CuO) were developed for potential uses in wound healing applications. PGF with 0, 1, 5 and 10 mol% CuO were produced with different diameters and characterised in terms of structural and antibacterial properties. The effect of CuO and fibre pulling speed on the glass properties were investigated using rapid differential scanning calorimetry, differential thermal analysis and X-ray diffraction. The effect of two fibre diameters on short-term (3 h) attachment and killing against Staphylococcus epidermidis were investigated and were related to their rate of degradation in deionised water, as well as copper ion release measured using ion chromatography. Thermal analysis showed that there was a significant increase in the PGF glass transition temperature as the CuO content increased. There was a significant decrease in the rate of degradation with increasing CuO content and an increase in fibre diameter. Over 6 h, both the amount and rate of copper ions released increased with CuO content, as well as a reduction in fibre diameter thus increasing the surface area to volume ratio. There was a decrease in the number of viable staphylococci both attached to the CuO-containing fibres and in the surrounding environment.