Antibacterial properties of polyethylene and silicone rubber surface-modifiled by plasma generated from plasma focus device

Abstract

Surface modifications of polyethylene and silicone rubber were done using plasma generated from a plasma focus device operated with different types of gas including nitrogen, oxygen and argon. The number of plasma shots were also varied from 3, 5, 7 to 10 shots. It was found that the factors affecting the characteristics and antibacterial property of plasma-modified samples were copper content determined from atomic absorption spectroscopy, the formation of hydrophilic functional groups confirmed by FTIR spectroscopy and the surface roughness analyzed by atomic force microscopy. The results revealed that in the case of polyethylene, using 3 shots of nitrogen plasma or 5 shots of oxygen plasma resulted in highest antibacterial efficiency against S. aureus due to low surface roughness of the samples. For silicone rubber, highest antibacterial efficiency against S. aureus was obtained when 3 shots of nitrogen plasma were used. This was a result of the formation of hydrophilic functional groups and low surface roughness of the sample. Both cases indicated that copper ion implantation improved antibacterial efficiency against S. aureus. However, this method did not improve antibacterial property against E. coli of polyethylene and silicone rubber.