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

Chemical and gamma-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, H2O2, 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) gamma-irradiation also compromised sensor response, with exposed electrodes exhibiting approximately 30% reduction in response, comparable in magnitude to 10 min exposure to chemical sterilisation. However, a lower dose (25 KGy) gamma-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 degrees C in brain heart infusion medium.