2021 Volume 60 Issue 1 Pages 241-245
One of the major routes by which pathogenic microorganisms spread out is propagation through frequently hand touched surfaces. It is expected that introducing antibacterial metallic materials, such as copper and copper alloys, on frequently hand touched surface will keep environmental surfaces sterilized and prevent the spread of pathogen. When copper and copper alloys are used for frequently hand touched surfaces, their surfaces can be soiled due to human contact. As surface soling reduces antibacterial properties of copper and its alloys, it is necessary to clean the surfaces. Although cleaning removes contaminants on surfaces, the detergent used for cleaning may corrode copper surface resulting in degradation of the antibacterial properties. In medical facilities, sodium hypochlorite aq. and ethanol aq. are used as detergents. For sodium hypochlorite aq., it has been shown that adding anti–rust is effective for prevention of reduction in antibacterial properties, as well as surface texture, of copper. In this study, we investigated additives for ethanol aq. that keeps surface texture and antibacterial properties of oxygen–free copper. Acid added ethanol aq. was used as a detergent. The specimens were immersed in a detergent for 15 seconds and then dried in air for 1 hour. Such processes, designated as W–D cycles, were cyclically applied for specimens for 168 times. The surface of the specimens deteriorated with W–D cycles except the case that oxalic acid was used as an additive. Antibacterial properties of OFC subjected to the W–D cycles with oxalic acid added ethanol aq. was equivalent to those of OFC kept in air for the same period. Oxalic acid, which is used as food additives, is effective to prevent degradation in antibacterial properties of copper surface caused by wipe cleaning with ethanol aq.
