Fabrication of Robust Superhydrophobic Coatings onto High-Density Polyethylene Food Contact Surfaces for Enhanced Microbiological Food Safety

Lack of maintenance and poor sanitation of food-contact surfaces (FCSs) can result in foodborne microbial contamination and biofilm formation. With increasing industrial concerns over food safety and hygiene, it is important to keep FCSs bacteria-free to protect the consumers from various foodborne illnesses. In the current study, we report the fabrication of highly durable nanodiamond (ND) based coatings on high-density polyethylene (HDPE), combining the chemisorption of low surface energy ligands and rigid nanotexturing. The coated HDPE surfaces resulted in static, advancing, and receding water contact angles of 151.1 +/- 0.3 degrees, 155.0 +/- 1.0 degrees, and 151.0 +/- 1.9 degrees, respectively. This superhydrophobic coating demonstrated excellent mechanical durability, retaining its highly water-repellent nature after surface abrasion with spinach leaves and onion peels, as well as after 50 cycles of sand abrasion. In comparison to bare HDPE, the adhesion of Salmonella typhimurium LT2 and Listeria innocua bacteria onto the coated surfaces was reduced by 2.1 +/- 0.43 (>99.34%) and 1.6 +/- 0.55 (>97.75%) log-cycles, respectively. In addition, the coated substrates successfully reduced the cross-contamination of spinach leaves by S. typhimurium LT2 and L. innocua. Overall, this study demonstrates the proof-of-concept that durable superhydrophobic coatings involving nanodiamond on HDPE have the potential to reduce bacterial cross-contamination scenarios of FCSs in food processing environments.