Nanoengineered Surfaces for Controlling the Attachment of Pathogenic and Biofilm Forming Bacteria to Food Contact Surfaces

Non-Technical Summary: Foodborne illness continues to represent a serious public health threat in the United States and all over the world. Most of the microbial food safety problems are caused by the contamination of food processing equipment and food surfaces with harmful bacteria such as Listeria monocytogenes and Escherichia coli. Adherence of microorganisms to surfaces and subsequent biofilm formation in food processing environments leads to increased opportunity for microbial contamination of processed foods. A key element in the fight against pathogenic microorganisms in the food industry is the use of food contact materials that are not only cleanable, but could also prevent microbial adherence and biofilm formation. Recent scientific evidence demonstrates that nanostructured materials interact very differently with bacterial cells as compared to conventional materials. The working hypothesis of this project is that, by controlling nanophase material properties such as roughness, feature organization and porosity, it will be possible to control the attachment of foodborne bacterial pathogens and develop surfaces that can either effectively repel or capture and kill bacterial cells. The goal of this project is to generate an understanding of the fundamental rules of attachment of foodborne pathogenic bacteria to nanostructured surfaces, and then use these rules to design and develop nanoengineered surfaces able to control the attachment of bacteria to food contact surfaces. The project team will evaluate the effect of nanoscale surface details on the attachment of pathogenic and biofilm forming bacteria relevant to food processing, then use this knowledge to develop nanostructured food contact surfaces with both microbial repellant and microbial killing properties. The work will be carried out on materials compatible with foods and food processing environments and will use nanofabrication techniques feasible for food applications. This project is expected to have a significant positive impact on food safety and public health, since it will provide solutions for minimizing microbial biofilm formation and pathogen contamination in food processing plants, thus reducing the incidence of foodborne illness. <P> Approach: In order to ensure success of the proposed objectives and activities, a multi-disciplinary project team with collective expertise in food safety engineering, food engineering, nanoengineering and physics, food safety and microbiology has been assembled. The following activities, corresponding to each of the three objectives will be carried out. 1. Investigations on the effect of surface nanostructuring on attachment and biofilm formation by foodborne bacteria. We will carry out a systematic study to understand the effect of nanoscale surface topography on the selected challenge organisms. For this purpose, surfaces of the same chemical composition with surface features ranging from microscale to nanoscale will be fabricated in the Co-PDs laboratory. These surfaces will then be fully characterized and used in bacterial attachment and biofilm formation studies, which will be carried out by the PD's laboratory. Exploratory cleaning cycles of the substrates will also be performed, in order to ensure that the substrates fabricated in this work can be cleaned and can also resist the harsh cleaning conditions employed in the food industry. 2. Develop nanophase food contact surfaces with microbial repellant properties. Based on the findings of the first stage of the project, we will design and fabricate surfaces of the same chemical composition with surface features that hinder bacterial attachment. The selected patterns will be created on anodized alumina on aluminum substrate. Bacteria adhesion and biofilm formation on these surfaces will be evaluated and compared to a traditional finish of the same material. 3. Develop disinfecting microbe-trapping surfaces with antimicrobial coatings. Nanoscale patterns for microbe - trapping surfaces, will be defined and created on anodized alumina on aluminum substrate. Afterwards, nanopatterned substrates will be coated with either permanent antimicrobial coating (silver) or a biodegradable antimicrobial coating (nisin). The stability and antimicrobial activity of the coatings will be evaluated.