Comparative assessment of chemical and γ-irradiation procedures for implantable glucose enzyme electrodes

Abstract

Chemical and γ-irradiation sterilisation were examined in this study for implantable needle electrodes. Exposure to isopropyl alcohol (IPA) led to response elevation, but time-dependent exposures up to 30 min variously to chlorhexidine, H 2O 2, HCl, HCl/IPA, and alcoholic iodine/potassium iodide, all caused substantial time-dependent response degradation. Sterility was not assessed for such electrodes. High dose (30 KGy) γ-irradiation also compromised sensor response, with exposed electrodes exhibiting ∼30% reduction in response, comparable in magnitude to 10 min exposure to chemical sterilisation. However, a lower dose (25 KGy) γ-irradiation was well tolerated and subsequent microbiological testing (following contamination with Streptococcus epidermidis and Staphylococus aureus) proved device sterility with no culture growth following 7 days incubation at 37°C in brain heart infusion medium.