Supercritical CO2 sterilization of ultra-high molecular weight polyethylene

The aim of this study was to use a benign technique for the sterilization of ultra-high molecular weight polyethylene (UHMWPE), which is broadly used in artificial joints. The feasibility of using supercritical (SC) CO2 modified with additives such as ethanol, water and hydrogen peroxide was assessed for the sterilization of UHMWPE. The operating conditions and the amount of modifiers were changed to achieve a complete inactivation of bacteria such as spores and fungi. Complete inactivation of all microorganisms including spores was achieved within 2 h at 37 °C and 170 bar CO2, when at least 25 μL hydrogen peroxide was mixed with equal volume of other modifiers. The physio-chemical properties of the polymer were tested for untreated, as well as treated samples. Mechanical strength and elongation of the polymer were measured using an Instron and the oxidation of the polymer was measured using FTIR. Both the physical and chemical properties of the polymer were unchanged after the SC CO2 sterilization technique.