Biological behaviour of chitosan electrospun nanofibrous membranes after different neutralisation methods

Chitosan electrospun nanofibres were synthesised in two different trifluoroacetic acid (TFA)/dichloromethane (DCM) solvent ratios and then neutralised in aqueous and ethanol sodium-based solutions (NaOH and Na2CO3) to produce insoluble materials with enhanced biological properties for regenerative and tissue engineering applications. Structural, electronic, and optical properties and the swelling capacity of the prepared nanofibre membrane were studied by scanning electron microscopy, Fourier-transform infrared spectroscopy, and photoluminescence. Cell viability (with the U2OS cell line) and antibacterial properties (against Staphylococcus aureus and Escherichia coli) assays were used to assess the biomedical potential of the neutralised chitosan nanofibrous membranes. A 7:3 TFA/DCM ratio allows for an elaborate nanofibrous membrane with a more uniform fibre size distribution. Neutralisation in aqueous NaOH only maintains a partial fibrous structure. At the same time, neutralisation in NaOH ethanol-water maintains the structure during 1 month of degradation in phosphate-buffered saline and distilled water. All membranes demonstrate high biocompatibility, but neutralisation in ethanol solutions affects cell proliferation on materials made with 9:1 TFA/DCM. The prepared nanofibrous mats could constrain the growth of both gram-positive and gram-negative microorganisms, but 7:3 TFA/DCM membranes inhibited bacterial growth more efficiently. Based on structural, degradation, and biological properties, 7:3 TFA/DCM chitosan nanofibrous membranes neutralised by 70% ethanol/30% aqueous NaOH exhibit potential for biomedical and tissue engineering applications.