Switchable Antimicrobial and Antifouling Coatings from Tannic Acid-Scaffolded Binary Polymer Brushes

Surface biofouling has been a serious environmental and ecological problem for centuries. In this study, pH-sensitive poly(2-diisopropylaminoethyl methacrylate)-b-poly(2-methacryloyloxyethyl phosphorylcholine) (PDPA-b-PMPC) and cationic polylysine (PLYS) chains are grafted on tannic acid (TA). The resulting PLYS-TA-PDPA-b-PMPC can be anchored in ‘one-step’, via coordination chelation of TA, on substrate surfaces to impart the latter with switchable antimicrobial and antifouling functionalities. The PLYS-TA-PDPA-b-PMPC functionalized stainless steel (SS) surface exhibits significant antimicrobial (S. epidermidis and E. coli) activity, as well as resistance to protein adsorption, bacterial adhesion, and microalgal (Amphora coffeaeformis) attachment. The reversible transition between antimicrobial and antifouling effects is achieved in response to pH changes of the surrounding environment. Decrease in pH arising from bacterial adhesion/deposition switches the antimicrobial polymer brush coatings to the antif...