Protein-Resistant Behavior of Poly(ethylene glycol)-Containing Polymers with Phosphonate/Phosphate Units on Stainless Steel Surfaces

Stainless steel is used in a large variety of food and medical applications, where it is susceptible to adsorption of proteins and other materials on its surface, ultimately leading to biofouling. Here, we report the synthesis of a copolymer bearing both poly(ethylene glycol) (PEG)-antifouling and phosphate-containing monomers, abbreviated as poly(PEGMA-co-MEP), to be used as an easily applied nano-coating for a stainless steel substrate. Highly tenacious films could be easily deposited by dipping the stainless steel substrate into a dilute aqueous solution of the polymer for a few minutes, which then resisted rinsing over many days. This simple attachment method, which does not need solvents, annealing, or adhesion promoters, looks to be very easy transferable into commercial applications. From quartz crystal microbalance with dissipation experiments, the films were found only about one polymer layer thick. A variety of proteins and skim milk were tested against the poly(PEGMA-co-MEP)-coated surfaces, which showed almost a 100% reduction in binding affinity. In addition, fluorescence microscopy results showed that PEG phosphate and phosphonate-coated surfaces exhibited strong inhibition of bacterial adhesion for both Escherichia coli and Bacillus cereus over several days. Other PEG polymers containing carboxylic acids as anchoring groups were also tested and gave a somewhat worse performance.