Escherichia coli sterilization and lipopolysaccharide inactivation using microwave-induced argon plasma at atmospheric pressure

Upon fabricating medical devices and biomaterials, the inactivation of microorganisms harmful to human is very important. It is more important to remove killed bacteria and their debris, particularly pyrogens such as lipopolysaccharide (LPS) from medical devices. LPS, referred to as endotoxin, is derived from the cell wall of gram-negative bacteria and well-known for inducing various pathological diseases. In this study, the sterilization of Escherichia coli (E. coli) and elimination of E. coli-derived LPS were examined by using our self-designed microwave-induced plasma system at atmospheric pressure. Plasma treatment resulted in complete sterilization of E. coli after 1 s, which was confirmed by morphological alterations such as ruptured membranes and amorphous structures. Furthermore, LPS was completely inactivated after 10 s of plasma treatment. These results suggest that microwave-induced plasma will not only be effective on E. coli sterilization, but will also be able to remove LPS from the surface of the objects being sterilized. (C) 2006 Elsevier B.V. All rights reserved.