Functional surface coatings often fail because they get damaged or contaminated. In particular, contact-killing antimicrobial coatings become inactive when the debris of destroyed bacteria remains on the surface and covers the underlying active coating. New bacteria can settle and proliferate on such contaminations, and eventually form a biofilm on the surface. Once encapsulated in a biofilm, bacteria are inaccessible for antibiotics or the immune system. This makes biofilms a severe infection threat, in particular in the context of medical devices.
We here present a novel approach to combine polymer-based synthetic mimics of antimicrobial peptides (SMAMPs) with protein-repellant poly(zwitterionic) polymers. This should lead to materials that are simultaneously antimicrobial and antifouling. We followed two approaches: First, we synthesized poly(zwitterions) (PZIs) with a reactive end-group and grafted them onto a surface-attached SMAMP network. Depending on the grafting density, materials with dual activity were obtained. In the second approach, we created a chemical contrast on a surface using micro- and nanostructuring techniques, in particular colloidal lithography. Site-selective immobilization of SMAMPs and PZIs on the resulting pattern yielded structured combined SMAMP-PZI materials. We studied the resulting antimicrobial and antibiofouling properties with various techniques including surface plasmon resonance spectroscopy and antimicrobial assays and found that both the protein-repelling properties and the antimicrobial activity against Gram positive and Gram negative bacteria depended on the pattern periodicity. We will report our most recent progress in this paper.
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