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Keywords:

  • ethylene oxide sterilization;
  • poly(ethylene glycol);
  • tyrosine-derived polycarbonates;
  • fragile morphology;
  • EtO susceptible groups

Abstract

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Sterilization conditions need to be optimized to effectively neutralize the bioburden while using short exposure times for minimizing the changes in chemical composition, material properties and device architecture. Towards this goal, effects of ethylene oxide (EtO) exposure parameters such as time, temperature, humidity, and EtO concentration on the polymer properties were investigated by monitoring the changes in composition, and the morphology of different types of structures in a family of poly(ethylene glycol) (PEG)-containing tyrosine-derived polycarbonates. EtO was found to esterify the carboxyl groups present in the desaminotyrosyl-tyrosine groups. Sterilization under conditions more severe than those normally used reduced the glass transition temperature (Tg) and the molecular weight of the polymers, and the presence of PEG in the polymer enhanced this effect. Furthermore, electron micrographs showed that EtO sterilization cycle conditions, even those considered “mild,” were found to damage the fragile structures such as those found in electrospun mats and porous scaffolds. Our study shows that the presence of EtO-susceptible groups, fusible architecture, and surface morphology should be taken into account in choosing the appropriate EtO sterilization conditions. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.