The invention relates to a sterilizers and methods of sterilization of an instrument. The sterilizer includes an ozone generator, an air mover, an oxygen concentrator, and a controller. The ozone generator, which is housed by the sterilization chamber, generates at least one plasma field. The air mover circulates air through the sterilization chamber. The oxygen concentrator delivers oxygen-concentrated air to the sterilization chamber. The controller communicates with the ozone generator, the air mover, and the oxygen concentrator. The sterilizer may also include a battery to power the components of the sterilizer. A portable case may house the sterilizer.