Abstract
This study investigates a series of phosphate-glass fibres (PGF) in the system P2O5-CaO-MgONa2O-Fe2O3 with various Fe content (0, 0.1, 0.5, 1 and 2 weight %) prepared via electrospinning (ES) of polyphosphate coacervate gels. This method is preferable over the traditional high temperature melt-spinning technique (MS) used for PGF production as it represents a more cost-effective and sustainable route. Structural analysis performed via Fourier Transform Infrared spectroscopy (FT-IR) shows that PGF are mainly formed by polyphosphate chains containing Q1 and Q2 units. Thermal analysis demonstrates that the amorphous nature of PGF can be preserved up to calcination temperatures in the range 450-520 °C, with crystallisation temperatures increasing with the iron content. Dissolution studies were performed by immersing the PGF in deionised (DI) water and analysing the species released (P, Ca, Mg, Fe and Na) via Microwave Plasma Atomic Emission Spectroscopy (MP-AES) at regular intervals up to 72 hours (h). Results show that both iron and phosphate anions release increases with iron loading, suggesting that the phosphate network is weakened by an increasing amount of iron. Given that PGF are particularly advantageous in wound healing due to their fibrous morphology, their cytocompatibility was assessed by seeding human keratinocytes (HaCaTs) in contact with the dissolution products of PGF after 24 h of immersion at three different ratios of dissolution products to cell medium (1:100, 3:100 and 5:100). No cytotoxicity was observed for any of the ratios studied. Moreover, the dissolution products of some PGF resulted in an enhanced growth of HaCaT cells, with the best result being observed when using dissolution products from PGF containing 0.1 weight % of Fe and a dissolution product - cell medium ratio of 5:100. Dissolution products from PGF with an Fe content up to 0.5 weight % have also demonstrated antibacterial activity against the bacterium Escherichia coli (E. coli). A preliminary test on the efficacy of PGF in wound healing via ex vivo studies on human skin has demonstrated that PGF in direct contact with the wound promotes 84 % wound closure.