A method of removing endotoxins and other biologically active organic compounds from the surfaces of solid objects is based on exposure of the objects to monatomic oxygen generated in oxygen plasmas. The mon- atomic oxygen reacts strongly and preferentially with the organic contaminants to form volatile chemical species. The method was developed especially for removing such contaminants as lipopolysaccharides, proteins, lipids, and other biologically active contaminants from surfaces of orthopedic implants prior to sterilization and implantation; if not removed, these con- taminants can contribute to inflammation that sometimes necessitates the surgical removal of the implants.
A major advantage of this method is that unlike in prior methods of decontaminating implants, there is no need to expose the implants to strong liquid chemical baths or high temperatures, both of which can degrade implant materials. Moreover, whereas the prior methods do not ensure complete removal of the con- taminants, the present method ensures complete removal of the contaminants from all surfaces that receive sufficient exposure to monatomic oxygen.
The apparatus used to implement this method includes a vacuum chamber, a radio-frequency (RF) generator connected to electrodes in the chamber for generating a plasma, and a manipulator system (see figure). Included in the manipulator system are a special thermoplastic container for positioning one or more implant(s) or other object( s) for exposure to monatomic oxygen from the plasma, an actuator arm for manipulating the container, and a subsystem for heat-sealing the implant( s) or other object(s) in the container after treatment.