(599a) Solubility of E. Coli Endotoxins and Removal From Metallic Biomaterials Using Water-in-CO2 Microemulsuions

Bacterial endotoxins have strong affinity for metallic biomaterials because of surface energy effects. Conventional depyrogenation methods may not eradicate endotoxins and may compromise biological properties and functionality of metallic instruments and implants. We evaluated the solubilization and removal of E. coli endotoxin from smooth and porous titanium (Ti) surfaces and stainless steel lumens using a water-in-CO2 microemulsion phase. The microemulsion system in the liquid CO2 region (298 K and 27.6 MPa) with strong mixing removed all the endotoxin below detection levels. This suggests that formation of water-in-CO2 microemulsions penetrates and dissolves endotoxins from all the tested substrates. The successful removal of endotoxins from metallic biomaterials with compressed CO2 is a promising cleaning technology for biomaterials and reusable medical devices.