Selection of an optimal method for sterilization of the medical grade biodegradable polymers

Aim of this study was to assess possible influence of chitosan-based gels (without cross-linker treatment and cross-linked with one of the next substances - glutaraldehyde, hexamethylene diisocyanate or oxidized alginate) onto live tissues in in vivo animal model and evaluate and select optimal sterilization method of such biodegradable materials. Sterilization of all chitosan gel samples were performed using three different methods: steam sterilization, low-temperature hydrogen peroxide plasma and radiation sterilization. The best swelling degree values were obtained for chitosan gels cross-linked with glutaraldehyde or hexamethylene diisocyanate. Further in vivo animal model 14-day evaluation showed no toxic, immunosuppression or sensitization effects nor dystrophic and autoimmune changes in live tissues that have been directed in contact with implanted polymer. Among all three evaluated sterilization methods the best one was the radiation sterilization in terms of preserving the desired characteristics of swelling and minimal changes in chemical composition and properties of sterilized materials, even with 25 kGy absorbed dose that allows sterility assurance level at 10⁻⁶ to be achieved.