A Flexible Anti-Biofilm Hygiene Coating for Water Devices

Biofilm is a microbiome complex comprising different bacterial colonies that typically adhere to device surfaces in water, which causes serious medical issues such as indwelling infections and outbreaks. Here, we developed a non-nanoparticle, flexible anti-biofilm hygiene coating consisting of lithocholic acid (LCA), zinc pyrithione (Zn), and cinnamaldehyde (Cn) (named as LCA-Zn-Cn) that largely prevents the bacteria adhesion to various water device surfaces such as stainless steel and glass through a synergistic mechanism. The existing chelated groups on LCA and Cn attract plenty of bacteria via hydrophobic interaction. Both the bactericidal reaction by grafting biocidal groups from both LCA and Cn and the bacteriostatic reaction by inhibiting cell division via zinc ions (Zn) lead to a largely improved bacteria/biofilm prevention. The antibacterial performance was assessed by using the JIS Z 2801/ISO 22196 method. The designed LCA-Zn-Cn coating displayed log₁₀ reduction of 4.23 (99.9% reduction) of E. coli and log₁₀ reduction of 3.51 (99.8% reduction) of E. faecalis on stainless steel, which are much higher than the control samples, demonstrating a promising colonization inhibition. In parallel, the polysulfone encapsulated beads also showed >99% reduction efficiency in batch and >97-98% reduction efficiency in continuous column tests using the Lake Michigan water. Due to the strong cross-linked configuration, the coating still showed >90.9% bacterial reduction after 3000 abrasion cycles and over 99.9% bacteria reduction after a high flow velocity of 1.99 m/s test, which confirmed the enhanced mechanical durability. By applying either spray or dip-coating, the designed polymer composite can be coated on a variety of irregular water devices with mass production using an auto-controlled robot arm.