Antimicrobial assay on pvdf nanofiber membrane

Abstract

© 2020 Trans Tech Publications Ltd, Switzerland. Many researches concentrated on development of antimicrobial membranes for many applications such as air or water filtration. Disk diffusion was well-known conventional method for antimicrobial assay. However, this method was preferable to hydrophilic materials, where inhibition zone was easily observed. For hydrophobic materials, negative test was always shown, except increase in antimicrobial loading. In this study, glucose fermentation was introduced as a new method for antimicrobial assay. The survived and viable bacteria either at the surface or attached inside the membranes could ferment glucose resulting in acid production and changing color of indicator in the glucose solution from pale orange to pink. PVDF nanofiber membrane, so called FU8M and FA8M, loading with AgNO3 and Benzalkonium chloride (0.3-1.0%) were used as hydrophobic and hydrophilic membrane, respectively. The water absorption of these membranes took 2 h and 2 min, respectively, showing that the latter membrane improved its wettability. It is found that FU8M membrane showed no inhibition zone when the antimicrobial loading less than 1%, whereas the FA8M membrane showed inhibition zone from 8.6-14 mm, depending on antimicrobial loading. However, when glucose fermentation method was used, membranes showed the positive test after 9 hours of incubation at the antimicrobial concentration of 0.5%. Hence, this new method can be used as antimicrobial testing with simple and cost effective.