Material Compatibility of Poly(Ether)urethane 80A With Vaporized Hydrogen Peroxide Sterilization: A Comprehensive Evaluation of Oxidative Stability and Biocompatibility.

Abstract

Poly(ether)urethanes (PEUs) are widely used in long term implanted medical devices. Their susceptibility to oxidative degradation has raised concerns regarding compatibility with vaporized hydrogen peroxide (VH₂O₂) sterilization. This study investigates the chemical and mechanical stability of PEU80A, a Shore 80A durometer PEU, following exposure to VH₂O₂ sterilization. Two VH₂O₂ sterilization conditions were characterized, three times (nominal) and 10 times (extreme) the cycle required for cardiac pacemaker sterilization and compared to two solution-based hydrogen peroxide exposures, with and without cobalt chloride catalyst. Compared to the extreme VH₂O₂ condition, the solution exposure conditions were four orders of magnitude higher in concentration and 40-fold longer in duration. Comprehensive characterization of PEU80A included molar mass analysis, antioxidant quantification, mechanical testing, free radical profiling, soft segment loss assessment, exhaustive chemical extraction, and evaluations of hemocompatibility and cytotoxicity. The results demonstrated that VH₂O₂ sterilization did not induce any detectable degradation in PEU80A, even after 3 years of real-time aging post VH₂O₂ exposure. Only the catalyzed solution exposure resulted in measurable oxidative degradation, evidenced by antioxidant depletion, molar mass reduction, soft segment depletion, and mechanical weakening. Despite these changes, the comprehensive testing for chemical extractables, hemocompatibility, and cytotoxicity, used to evaluate biocompatibility, remained unaffected. These findings demonstrated the continued oxidative stability and biocompatibility of PEU80A after VH₂O₂ sterilization, supporting its use as a terminal sterilization method for implantable devices comprised of this material. Furthermore, these data suggest that the biostability of a material is impacted long before any changes in biocompatibility can be resolved.