Stimulus-Responsive Microphase-Separation of Resilin/Elastin Block-Copolypeptides in Solution and on Surfaces

We investigated the self-assembly of a series of stimulus-responsive block copolypeptides (BCPs) composed of a hydrophobic, resilin-like domain and a hydrophilic, elastin-like domain in the bulk and on surfaces using small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). We observed classical, microphase-separated nanostructures, such as hexagonally-packed cylinders and alternating lamella, in concentrated solutions of the block copolypeptides. The emergence of these nanostructures was strongly dependent on copolymer composition and temperature. Discrete order-order transitions were observed for higher molecular weight species, and order-disorder transitions were observed with increasing temperature for all species due to the lower-critical solution behavior of the elastin-like block. BCP thin-films also exhibited microphase-separated nanostructures that resembled those in solution. and could be further refined by annealing in a high humidity environment, resulting in long-range, periodic nanostructures. For example, these structures can function as templates to guide the self-assembly of molecules or other nanoscale objects, and thus enable a broad range of biocatalytic, bioelectronic, or assay devices.