Development of a novel low-temperature sterilization procedure using supercritical carbon dioxide and of compatible nanocomposites for medical devices
IGF 98 EN
Thermolabile medical devices which are surgically inserted, such as flexible endoscopes that are applied in the aseptic visceral cavity, are classified as “critical C”-devices with regard to reprocessing. These devices are sterilized using special low-temperature procedures. Conventional low-temperature procedures relay on toxic chemical agents like e.g. ethylene oxide or on the application of ionizing radiation (60Co). Other procedures are under dispute with regard to process performance when applied to geometrically complex devices. Aim of the project was the development of a novel low-temperature procedure (< 40 °C) using highly compressed supercritical carbon dioxide (SCCO2) allowing sterilization of thermolabile, geometrically complex medical devices such as e.g. flexible endoscopes. This research work was performed by the wfk – Cleaning Technology Institute (Germany). Suitable process challenge devices (PCDs) were developed and applied with different microorganisms in SCCO2 processes to quantify the antimicrobial effect. An appropriate additive combination was developed and used to enhance the antimicrobial effect. Various sterile barrier systems were investigated for their compatibility with the developed SCCO2 method and a suitable system based on Tyvek®/film was chosen. Results showed that phase-transition-cycles (supercritical CO2 ➝ liquid CO2) and relative movement of SCCO2 have a considerable positive effect on the inactivation of microorganisms in particular when applied on complex PCDs. The efficacy of the SCCO2 process was confirmed on complex tubular PCDs. In practice, based on the characterized parameters, the process has to be adapted depending on the medical devices to be sterilized.
In parallel Montanuniversität Leoben (Austria) developed novel polymer materials with compatibility against SCCO2 sterilization procedures to be available for the manufacturing of medical devices such as e.g. flexible endoscopes. By incorporation of nanoparticles (e.g. cellulose or zeolite) as filler substances these polymers exhibited improved barrier/diffusion properties and compatibility against SCCO2. The application of 2-5 % nanoscaled fillers showed most improved results regarding minimization of CO2 uptake (reduced by up to 90 %) and mechanical properties. Four materials which showed excellent compatibility against SCCO2 were developed and are now ready for the development of future generations of medical devices.
Reprocessing service providers/central sterilisation service staff, operators of devices, physicians as well as patients of the 30,000 hospitals and countless doctor´s offices within the EU benefit from the project results. Further beneficiaries are manufacturers of high pressure devices and sterilisation devices. The development of new nanocomposites will be profitable for several thousand medtech companies for the evolution of a new generation of medical devices.
The IGF-project 98 EN of the research association Europäische Forschungsgemeinschaft Reinigungs- und Hygienetechnologie e.V., Campus Fichtenhain 11, D-47807 Krefeld, was supported via the AiF within the funding programme „Industrielle Gemeinschaftsforschung und –entwicklung (IGF)“ by the Federal Ministry of Economic Affairs and Energy (BMWi) due to a decision of the German Parliament.
The research report is available on request from FRT.