Polyampholyte Thin Film Hydrogels for the Prevention of Ralstonia pickettii Adhesion

Potable water systems are especially susceptible to biofilm formation leading to significant impacts on both the mechanical components of the systems and human health upon consumption. As a result, industry and healthcare both suffer significant financial burdens from the effects of biofilm formation. This study investigates the application of cross-linked polyampholyte copolymer thin film hydrogels to prevent bacterial adhesion to stainless steel, a common material of construction for potable water systems. Here, [2-(acryloyloxy)ethyl] trimethylammonium chloride (TMA) and 2-carboxyethyl acrylate (CAA) thin film hydrogel coatings were coupled to stainless steel using (3-acryloxypropyl) trichlorosilane. Thin films hydrogels cross-linked with zwitterionic carboxybetaine dimethacrylate or [N-(2-ammonio-3-(methacryloyloxy)propanoyl)-O-methacryloylserinate were evaluated and compared to thin films cross-linked with diethylene glycol dimethacrylate as a control. Thin films were formed and characterized for a variety of silane coupling agent concentrations and spin coating conditions and the bacterial adhesion and subsequent biofilm formation of Ralstonia (R.) pickettii was then evaluated. After bacteria exposure periods of 1, 2, or 7 days, R. pickettii adhesion on the samples was analyzed using confocal microscopy. Both zwitterionic cross-linkers enhanced the ability of the TMA/CAA thin film hydrogels to reduce bacterial adhesion compared to the control cross-linker, reducing bacteria surface coverage to less than 0.6% after 7 days of bacteria exposure and growth under the optimal coating conditions. The results suggest that polyampholyte thin film hydrogels have great potential for reducing bacterial growth in potable water systems when applied using optimal coating procedures.