The effect of Ethylene Oxide Sterilisation, Beta Irradiation and Gamma Irradiation on Collagen Fibril-Based Scaffolds.

Ethylene oxide (EtO) gassing and β- and γ-irradiation are currently used for sterilising collagen scaffolds. During the process, scaffolds may undergo chemical and physical alterations that may compromise their structural integrity and functional characteristics. In this study, we compared the effects of EtO gassing, and β- and γ-irradia- tion at 15 and 25 kGy on type I collagen fibril-based scaffolds with and without crosslinking, and with and without heparin. Evaluation was performed using a wide range of biophysical, biochemical, morphological and biological parameters. EtO treatment, β-irradiation and γ-irradiation did not induce morphological changes, nor did they have an effect on the amount of primary amine groups, or the amount of heparin covalently attached to the scaffolds. Cyto- compatibility was also not affected. Irradiation, however, did result in collagen degradation products, a decrease in collagen denaturation temperature, and an increase in proteolytic degradation, all in a dose dependent fashion. These parameters were hardly influenced by EtO treatment. Sterilisation methods had hardly any effect on tensile strength of crosslinked scaffolds, but -surprisingly- they increased the tensile strength of non-crosslinked scaffolds. In con- clusion, a number of the collagen scaffold parameters were influenced by sterilisation, whereas others were not. Irra- diation had a much larger effect than EtO. However, tensile strength and cytocompatibility, important in tissue engineering, were not negatively influenced by any of the methods. Therefore, aspects like costs, safety and practi- cality of use may be taken into account in the choice of sterilisation method.