Superhydrophobic and Superhydrophilic Nanocomposite Coatings for Preventing Microbial Adhesion on Liquid Food Contact Surface

N. Rungraeng, S.H. Yoon, W. Song, S. Jun
University of Hawaii at Manoa, US

Keywords: bacterial adhesion, Escherichia coli, nanocomposite coating, carbon nanotubes, titanium dioxide


Pathogenic microbes in biofilm matrix increase the potential of cross-contamination with processed food products, subsequently resulting in food borne disease outbreaks. Prevention of bacterial adhesion on food contact surfaces will have a massive impact in the formation of biofilm and contamination problem. Many recent studies have shown that both superhydrophobic and superhydrophilic coatings can minimize microbial adhesion on solid substrates; however, a comprehensive investigation of both extreme surface characteristics is not available. Therefore,the ultimate aim of this paper is to test and evaluate the rate of microbial adhesion on liquid transport system by comparing the effects of superhydrophobic and superhydrophilic surface coatings. The flow chamber was mounted with three different surfaces including uncoated stainless steel (control) plate, superhydrophobic and superhydrophilic coated plates. For adhesion experiments, the suspension of 3×10^8 cells/ml Escherichia coli K-12 was pumped through the chamber at two flow rates of 0 (stagnant) and 200 ml/min (wet surface). Increases in flow rate and hydrodynamic force significantly inhibited the bacterial adhesion on both developed surfaces. After running for an hour, the fluorescence intensities (FIs) of adhered bacteria on superhydrophobic and superhydrophilic surfaces were up to 80 and 65 percent lower than uncoated surface, depending upon the surface wetness.