Effect of the sterilization method on the properties of Bombyx mori silk fibroin films

• Published in: Materials Science & Engineering C Vol. 33; no. 2; pp. 668 - 674
• Main Authors: George, Karina A., Shadforth, Audra M.A., Chirila, Traian V., Laurent, Matthieu J., Stephenson, Sally-Anne, Edwards, Grant A., Madden, Peter W., Hutmacher, Dietmar W., Harkin, Damien G.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-03-2013
• Subjects: Animals; Biocompatible Materials - chemistry; Biocompatible Materials - pharmacology; Bombyx; Cell adhesion; Cell Adhesion - drug effects; Cell Culture Techniques - methods; Cell Line; Degradation; Fibroins - chemistry; Fibroins - pharmacology; Fibroins - physiology; Humans; Silk fibroin; Sterilization; Surface Properties; Tensile properties; Tensile Strength - physiology; Tissue Engineering; Degradation; Silk fibroin; Tensile properties; Sterilization; Cell adhesion
• ISSN: 0928-4931; 1873-0191
• DOI: 10.1016/j.msec.2012.10.016

We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method.
► The effects of four methods of sterilization on the properties of silk fibroin films were investigated. ► Steam treatment leads to stiffer films but to lower transparency and variable surface topography. ► Degradation of fibroin is enhanced in the films that were gamma-irradiated. ► The effects on mechanical properties are explained through changes in both primary and secondary structure of fibroin. ► Gamma-irradiation and immersion in aqueous ethanol are suggested as preferred methods of sterilization.