Investigation of a Sterilization System Using Active Oxygen Species Generated by Ultraviolet Irradiation

Abstract

We have been investigating an advanced sterilization system that employs active oxygen species AOS . We designed the sterilization equipment, including an evacuation system, which generates AOS from pure oxygen gas using ultraviolet irradiation, in order to study the conditions necessary for sterilization in the system s chamber. Using Geobachillus stearothermophilus spores 10 6 CFU in a sterile bag as a biological indicator BI in the chamber of the AOS sterilization apparatus, we examined the viability of the BI as a function of exposure time, assessing the role of the decompression level in the sterilization performance. We found that the survival curves showed exponential reduction, and that the decompression level did not exert a significant influence on the survival curve. Subsequently, we investigated the sterilization effect as influenced by the spatial and environmental temperature variation throughout the chamber, and found that the sterilization effect varied with position, due to the varying environmental temperature in the respective areas. We confirmed that temperature is one of the most important factors influencing sterilization in the chamber, and estimated the temperature effect on the distribution of atomic oxygen concentration, using the quartz crystal microbalance QCM method with fluorocarbon thin film prepared by radio frequency sputtering.

Bactericidal Activity of TiO2 Nanotube Thin Films on Si by Photocatalytic Generation of Active Oxygen Species

“…Therefore, differences in the cell wall structure and chemical composition between Gram-positive and Gram-negative bacteria are thought to be one of the reasons for differences in resistance to ROSs, which is consistent with results from previous studies. 39,40 Although only two bacteria were investigated in this study, the effectiveness and applicability of this bactericidal method will become clearer if other bacteria are also investigated comprehensively using this bactericidal method. This will be the subject of future research.…”

Chemical stability of a colorimetric indicator based on sodium alginate thin film and methylene blue dye upon active oxygen species exposure

“…It is well known that atomic oxygen [O( 1 D)], ozone (O 3 ), and hydroxyl radicals (OH * ) are valuable in surface modification. AOS can be generated using ultraviolet (UV) lamps emitting light with 185 and 254 nm wavelengths, 1) and it has been proposed that the AOS that are generated in experimental chambers form as follows. The reactions are conducted in the presence of UV light with a 185 nm wavelength, causing a ground-state oxygen molecule ( 3 O 2 ) to decompose into two ground-state oxygen atoms [O( 3 P)].…”

“…9) AOS sterilization offers various advantages, such as low-temperature and dry processing, no toxicant residual effects, and low operating costs. 1) AOS exposure leads to microorganism inactivation. 10) In order to establish this technology for use with AOS, determining the presence of AOS and providing an indicator for the sterilization process is necessary; moreover, technology for detecting reactive AOS is highly necessary.…”

Evaluation of Low-Temperature Sterilization using Hydrogen Peroxide Gas Containing Peracetic Acid

“…Low-temperature sterilization methods, including ethylene oxide gas (EOG) sterilization, low-temperature steam formaldehyde sterilization, and hydrogen peroxide gas (plasma) sterilization, are widely used to sterilize materials such as non-heat resistant plastic and rubber products (Dai et al,2016;Yoshino et al, 2015) . The hydrogen peroxide gas (plasma) sterilization method has been widely used in the medical field (Japanese Society of Medical Instrumentation, 2014) , because it uses a sterilant with lower toxicity than those in EOG sterilization or low-temperature steam formaldehyde sterilization methods (Bathina et al, 1998) .…”