Multifunctional phosphate-based glass fibres prepared via electrospinning of coacervate precursors: controlled delivery, biocompatibility and antibacterial activity

There is an increasing demand for new biomaterials that both rapidly stimulate healing and prevent infections. Being bioresorbable, phosphate-glass fibres can simultaneously induce tissue regeneration and deliver therapeutic agents (e.g. antibacterial ions) in a controlled way. Here we present a series of copper-doped phosphate-based glass fibres in the P2O5-CaO-Na2O-(CuO)(x) system (x = 0, 1, 3, and 5 mol%) prepared for the first time via electrospinning of coacervate precursors. This method presents several advantages over the conventional high temperature melt spinning; the synthesis of the coacervate occurs at room temperature and in aqueous solution allowing the incorporation of temperature sensitive molecules. Moreover, electrospinning is an inexpensive, sustainable, easily scalable manufacturing process. The fibres produced are cotton-like, fully amorphous with an average diameter in the range 1-3 mu m. Dissolution studies on cations (Ca2+, Na+ and Cu2+) and phosphate anions (PO43-, P2O74-, and P3O105-) show a gradual release of all species in solution over time, ideal for controlled drug delivery applications. The antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was found to increase with increasing Cu2+ content and was found to be more effective against E. coli than against S. aureus. Interestingly, Cu2+ content seem to have a positive effect on cytocompatibility. Tests performed on osteoblast-like MG63 osteosarcoma cells have shown that the copper doped phosphate-glass fibres have a significantly better capacity to regenerate bone tissue than the undoped glass fibres. These findings suggest that phosphate-based glass fibres are promising multifunctional biomaterials for both antibacterial activity and tissue regeneration.