A Versatile and Robust Approach to Stimuli-Responsive Protein Multilayers with Biologically Enabled Unique Functions.

Protein-based materials call for innovative processing techniques to integrate their unique biologically enabled functions with other materials of complementary features. Herein, we report the covalent protein layer-by-layer assembly via orthogonal "Tag-Catcher" reactions as a facile and robust approach to make entirely protein-based multilayers on a variety of substrates. Programmed assembly of native telechelic proteins not only endows the materials valuable stimuli-sensitive behaviors, but also unique properties unparalleled by any synthetic counterparts. As proof of concept, super uranyl-binding protein (SUP) is immobilized on silica gel by this method with tunable capacity and enhanced capability for uranyl sequestration. Not only is the capturing performance enhanced in the multilayer setup, it also confers resilience to recycling, allowing efficient harvest of uranyl with an average of ∼90% and ∼60% recovery rate in over 10 cycles from water and synthetic seawater, respectively. The approach is the first entirely protein-based multilayers covalently assembled by the layer-by-layer method. It provides a platform for immobilizing proteins with synergistic enhancement of function and resilience and expands the scope and capability of genetically encoded protein-based materials.