Contact-active antimicrobial polymer surfaces bear cationic charges and kill or deactivate bacteria by interaction with the negatively charged parts of their cell envelope (lipopolysaccharides, peptidoglycan, and membrane lipids). The exact mechanism of this interaction is still under debate. While cationic antimicrobial polymer surfaces can be very useful for short-term applications, they lose their activity once they are contaminated by a sufficiently thick layer of adhering biomolecules or bacterial cell debris. This layer shields incoming bacteria from the antimicrobially active cationic surface moieties. Besides discussing antimicrobial surfaces, this feature article focuses on recent strategies that were developed to overcome the contamination problem. This includes bifunctional materials with simultaneously presented antimicrobial and protein-repellent moieties; polymer surfaces that can be switched from an antimicrobial, cell-attractive to a cell-repellent state; polymer surfaces that can be regenerated by enzyme action; degradable antimicrobial polymers; and antimicrobial polymer surfaces with removable top layers.

A manufacturing process for the site-selective modification of structured (bio)material surfaces with two different polymers/biomolecules is presented. In the first step, a chemical surface contrast is created (e.g., a gold-on-silicon contrast obtained by colloidal lithography), and is combined with two orthogonal surface reactions for polymer/ biomolecule immobilization. To demonstrate this, an antimicrobial SMAMP polymer and a protein-repellent polyzwitterion were site-selectively surface-immobilized on the gold−silicon structures. By varying the structure spacing and the surface architecture, structure−property relationships for the interaction of these bifunctional polymer surfaces with bacteria and proteins were obtained (studied by fluorescence microscopy, atomic force microscopy, surface plasmon resonance spectroscopy, and antimicrobial assays). At 1 μm spacing, a fully antimicrobially active bifunctional material was obtained, which also nearquantitatively reduced protein adhesion. As the process is generally applicable to polymers/biomolecules with aliphatic CHgroups, it is an interesting platform technology for site-selectively functionalized bifunctional (Bio)MEMS.

The synthesis and characterization of a series of green‐, blue‐, and red‐fluorescent exo‐oxanorbornene acid and imide monomers carrying nitrobenzofurazan, coumarin, and rhodamin B, respectively, as fluorophores are presented. These monomers carry oxanorbornene as polymerizable unit, and are readily copolymerized with bioactive functional oxanorbornene monomers by ring‐opening metathesis polymerization, as demonstrated by gel permeation chromatography and NMR spectroscopy. Due to the ease of synthesis of these monomers, and their cost‐effectiveness compared many to other fluorescent probes, they are useful for biomaterial applications.