Effect of sterilisation by gamma irradiation on the ability of polycaprolactone (PCL) to act as a scaffold material

Polycaprolactone (PCL) is a promising potential material for tissue engineering scaffolds. This paper investigates the effect of sterilisation by gamma irradiation (dose 2.5 Mrad) on degradation rate (catalysed by lipase), mechanical properties and the ability of cells to attach and subsequently grow on its surface. Gel permeation chromatography (GPC) was used to determine the effects of gamma irradiation of weight average, Mw, and number average, Mn, molecular weights. Gamma irradiation significantly decreased the rate of degradation, although the rates depended on the initial mass of polymer. It also significantly altered the mechanical properties, increasing the yield stress. PCL failed in tension by three different mechanisms. Irradiation significantly increased the failure stress, when the failure mechanisms were considered separately but not when they were combined. It caused a significant increase in Mw and decrease in Mn that could be attributed to chain scission and crosslinking. Chondrocyte attachment and growth on PCL was not significantly affected by gamma irradiation.