Effect of post-drawing and tension on enzymatic degradation of electrospun polycaprolactone nanofibers

Electrospun polycaprolactone nanofibers were enzymatically degraded to evaluate the effect of post-draw processing and tension on the rate of degradation. Electrospun polycaprolactone (PCL) nanofibers were drawn to increasing lengths, then submerged in pseudomonas lipase (PS Lipase) solution for a 7-day period. The degradation process and extent of deterioration were evaluated by changes in mass, tensile strength, percent crystallinity, molecular weight, and macromolecular chain alignment on day 0, 3, and 7. The rate of degradation was dependent on the percent crystallinity of the fiber and the degree of alignment in crystalline and amorphous portions of the fiber. Post-drawn PCL fibers maintained mass and tensile strength over 7 days in PS Lipase, while undrawn fibers, degraded within 1 day. Pretension in fibers before enzymatic incubation was critical to maintain the macromolecular structure and tensile strength over the degradation period. Loss of mass and mechanical strength without molecular weight reduction indicated that degradation occured via surface erosion of the material over time rather than enzyme penetration and bulk degradation. Measurement of crystallinity and chain alignment illustrated the effect of automated track drawing on the progression of crystal growth and chain alignment, as well as the changes in macromolecular structure which occurred during the multi-day degradation period.