Abstract
In this work, a novel route for the synthesis of porous phosphate-based glass fibres (PGFs) in the system P2O5-CaO-Na2O-xGa2O3 (x = 0, 0.2, 0.5 and 1 mol %) via electrospinning (ES) of polyphosphate gels is presented. Polyphosphate gels, prepared via the sustainable, fast and cost-effective technique of coacervation, are combined with the surfactant Pluronic 123 (P123) as a porogen, which is a very novel aspect of this work as no previous porous PGF have been manufactured via this method.
Porosity in PGFs is generated by removal of P123 via calcination. Scanning electron microscopy (SEM) demonstrates the presence of pores in the 100 nm-2 µm range, often aligned along the direction of the fibres. The structure of all PGFs was investigated using the complementary techniques of X-ray diffraction (XRD), Raman and Fourier Transform Infrared (FT-IR) spectroscopies. Energy Dispersive X-ray Spectroscopy (EDX) was used to assess the elemental composition of PGFs. Release of species following 3, 24, 48 and 72 hours of immersion in deionised water (DI) was investigated via microwave plasma atomic emission spectroscopy (MP-AES). Dissolution products after 24 hours of immersion of all PGFs in water (DI) were tested for antibacterial activity against the bacteria Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Results show that all PGFs are active against E. coli, whereas only PGFs containing the highest gallium content are active against S. aureus. MTT and MTS assays, colorimetric assays routinely used for measuring cellular growth and metabolic activity, demonstrate that 24 hours dissolution products are non-cytotoxic when in contact with keratinocyte cells (HaCaTs).
PGFs show high encapsulation efficiency (~ 99.99%) of the natural antioxidant clove oil (3 v/v%). Antioxidant activity (DPPH) and total phenolic content (TPC) assays performed on clove oil loaded PGFs show that antioxidant properties increase with the gallium content. This work demonstrates the feasibility of manufacturing porous PGFs with antioxidant and antibacterial properties for wound healing applications using the sustainable and cost-effective method of coacervation.