Development of a Self-Slippery Liquid-Infused Porous Surface (SLIPS) Coating Using Carbon Nanotube Composite for Repelling Food Debris and Microbial Biofilms

This study demonstrates the fabrication and anti-adhesion attributes of a self-cleaning surface (self-slippery liquid-infused porous surface, or SLIPS) by modifying the surface of a stainless steel plate. The surface consisted mainly of a superhydrophobic multiwalled carbon nanotube (MWCNT) and Teflon composite layer infused with a low surface tension liquid lubricant (Krytox). The degree of slipperiness of the developed SLIPS was measured by estimating the sliding angles of 500 I¼L water droplets as well as oil, ketchup, and honey droplets. To evaluate the anti-biofilm performance of the slippery nanocomposite surface, Escherichia coli K-12 and Staphylococcus aureus (10 8 CFU mL -1 ) biofilms were separately grown on stainless steel (control) and the SLIPS for seven days. Water, oil, ketchup, and honey droplets as well as the bacterial biofilms readily slid off the SLIPS without leaving any noticeable debris when the tilting angles were in the range of 1° to 20°, depending on droplets and biofilms. The slipperiness of the nanocomposite coating did not change over the seven days of the experiment. Crystal violet-dye absorbance measurement at OD 590 nm showed about 90% average reduction in biofilm formation on the SLIPS compared to the control stainless steel. Reducing pathogenic bacterial biofilms on food contact surfaces in food processing environments would decrease the risk of cross-contamination by biofilms, which can cause serious problems in ready-to-eat food products.