Electrically Switchable Polymer Brushes for Protein Capture and Release in Biological Environments

Interfaces functionalized with polymers are known for providing excellent resistance towards biomolecular adsorption and for their ability to bind high amounts of protein while preserving their structure. However, making an interface that switches between these two states has proven challenging and concepts to date rely on changes in the physiochemical environment, which is static in biological systems. Here we present the first interface that can be electrically switched between a high‐capacity (>1 μg cm−2) multilayer protein binding state and a completely non‐fouling state (no detectable adsorption). Switching is possible over multiple cycles without any regeneration. Importantly, switching works even when the interface is in direct contact with biological fluids and a buffered environment. The technology offers many applications such as zero fouling on demand, patterning or separation of proteins as well as controlled release of biologics in a physiological environment, showing high potential for future drug delivery in vivo. pH‐responsive polymer brushes are presented that are compatible with electrochemical control. The brushes can be reversibly switched between protein binding and repelling states at fully physiological conditions with respect to salt, pH and buffering capacity. Proof‐of‐principle experiments are shown for applications such as non‐fouling, patterning and controlled release of proteins in biological environments.