Hydrolytic degradation behaviour of electrospun poly(ɛ-caprolactone) filaments for biological tissue repair

Electrospun polymeric fibres are promising materials for biomedical applications, owing to their biocompatibility, biodegradability, and ability to be assembled into a non-woven fibrous mesh. In particular, continuous filaments can be produced and subsequently assembled into multi-filament braided structures for ligament and tendon tissue repair. In these applications, characterising the evolution of the mechanical properties of the filament as it degrades is of primary importance. The role of applied mechanical loads during the degradation process also needs to be understood. In this study, we characterised the hydrolytic degradation behaviour of pre-stretched electrospun filaments made of poly(ɛ- caprolactone) (PCL) in buffer saline solution at 45 °C for up to 5 weeks, considering both non-loaded and loaded conditions. We show that PCL filaments degrade significantly over this relatively short time period, with non-loaded specimens showing a 21 % reduction in molecular weight after 5 weeks of exposure. Tensile loads applied during degradation further accelerate the degradation rate, with filaments subjected to a 25 g load showing a 33 % reduction in molecular weight over the same time period. Applied loads also impact the mechanical properties of the degraded specimens, causing an increase in elastic modulus and strength but a sharp decrease in elongation at break with exposure time. Our findings have implications for the design of PCL electrospun constructs in load bearing biomedical applications.