Inhibitory Effects of Copper-Vermiculite Against E. coli

Friday, October 10, 2008 3:00 – 3:30 pm
Room 610, M&M Building

Bowen Li
Graduate Student
Department of Materials Science and Engineering
Michigan Technological University

Abstract

Copper vermiculite (Cu-V) is new type of synthetic antimicrobial agent havingpotential as a functional additive in products such as plastics, paints, leathers, andwoods to reduce microbial persistence and biofilm formation. The Cu-V wasprepared by cation exchange reaction, and characterized by SEM and XRD; theCu atoms were homogeneously dispersed in the vermiculite structure. Theantibacterial efficiency of Cu-V was evaluated by determining its minimuminhibitory concentration (MIC) against Escherichia coli. In the control vermiculitesuspensions, E. coli densities remained constant during the 12 hour contact time;in contrast, bacteria levels with Cu-V significantly decreased. In the experimentwith 200 ppm Cu-V (5.10 ppm Cu), viable E. coli levels were reduced by 94.8% at1 hour, 99.6% at 2 hours, and >99.9% at 4 hours. The Cu-V MIC level against E.coli was10 ppm, while the untreated vermiculite had no antibacterial activity. Verylittle Cu was detected in the suspensions during the study, indicating that the CuV’s antimicrobial effect was due to surface interactions.


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