NASA's research into protecting space craft from the highly reactive atomic oxygen in low-Earth orbit has lead to a decontamination method that removes endotoxins from medical implant surfaces. Endotoxins are fragmented remains of bacteria that are bioactive and may linger on implants even after sterilization. “They cause inflammation, pain, and joint loosening,” says Bruce Banks, chief of Electro-Physics Branch at NASA Glenn in Cleveland. “They're difficult to remove by conventional chemistry, and you would not want to damage the implants by heating them to eliminate the endotoxins.” However, atomic oxygen is so reactive it completely oxidizes and removes the endotoxins from the surfaces of implants and materials.

NASA's initial concern was not to allow bacteria to hitch hike on spacecraft traveling to other planets where they could pollute the environment with bacteria or viruses from Earth. In addition, missions looking for evidence of life could be compromised by bacteria brought from Earth. “While simulating low-Earth orbit, we discovered that pure oxygen would react with surface bioactive contaminants effectively, cleaning them better than other methods,” says Banks.

He says his group has shown oxygen ions kill some of the toughest bacteria, even Deinococous radiodurans, the industry standard once found in canned meat. “These bacteria can reconstruct their DNA and keep growing even after enormous doses of radiation,” he says.

Researchers generate atomic oxygen using a bench-top sized device or one about 4 ft. × 6 ft. × 3 feet for large objects. Both devices generate radio frequency plasmas at 13.5 MHz in low-pressure air. The plasmas break apart the O₂ to form atomic oxygen. “Researchers at Case Western Reserve University, Cleveland, have validated that the process does indeed completely remove the endotoxins,” says Banks. Atomic oxygen from the process has also been used to clean old paintings of soot by turning it into CO and CO₂.