This research presents the first optimised protocol for submersion of electrospun polycaprolactone (PCL) fibres in sodium hydroxide (NaOH) to improve surface hydrophilicity, and hence biocompatibility, without compromising material properties. The study comprised two aims: (1) identify the leading NaOH concentration (0, 0.1, 1, and 10 M) and submersion time (0, 1, 4, and 24 h) to improve hydrophilicity with minimal impact on tensile properties and (2) once identified, undertake material characterisation and in vitro testing for validation. 1 M 4 h (NaOH concentration: 1 M, submersion time: 4 h) improved hydrophilicity (aligned fibres at 0 M NaOH and 0 h submersion time reduced from 97±3° to 6±2°; and random fibres at 0 M 0 h reduced from 105±4° to 15±7°) with minimal impact on tensile strength (9% and 6% loss aligned and random, respectively). 1 M 4 h-treated scaffolds demonstrated no significant change in material properties, yet notably improved protein adsorption and attachment, viability and elongation of 3T3 fibroblasts 4 h postseeding. Thus, 1 M 4 h is optimal for successful wet chemical treatment of electrospun PCL and presents a simple and economical method to easily enhance biocompatibility without compromising scaffold integrity.

The annulus fibrosus—one of the two tissues comprising the intervertebral disc—is susceptible to injury and disease, leading to chronic pain and rupture. A synthetic, biodegradable material could provide a suitable scaffold that alleviates this pain and supports repair through tissue regeneration. The transfer of properties, particularly biomechanical, from scaffold to new tissue is essential and should occur at the same rate to prevent graft failure post-implantation. This study outlines the effect of hydrolytic degradation on the material properties of a novel blend of polycaprolactone and poly(lactic acid) electrospun nanofibers (50:50) over a six-month period following storage in phosphate buffered saline solution at 37 °C. As expected, the molecular weight distribution for this blend decreased over the 180-day period. This was in line with significant changes to fiber morphology, which appeared swollen and merged following observation using Scanning Electron Microscopy. Similarly, hydrolysis resulted in considerable remodeling of the scaffolds’ polymer chains as demonstrated by sharp increases in percentage crystallinity and tensile properties becoming stiffer, stronger and more brittle over time. These mechanical data remained within the range reported for human annulus fibrosus tissue and their long-term efficacy further supports this novel blend as a potential scaffold to support tissue regeneration.