Fig. 1. PhoCoil structure and stimuli-responsive properties.

PhoCoil hydrogels are physically self-assembled through homopentameric coiled-coil bundle formation. These bundles are held together by noncovalent interactions along the length of the helices, primarily between amino acids at the a and d positions.The noncovalent nature of these associations endows the bulk gel with shear-thinning and self-healing properties in response to applied force. The network degrades in response to 405 nm light due to the cleavage of the peptide backbone within the chromophore of PhoCl. During this process, PhoCl temporarily occupies a red state prior to the diffusive separation of the two protein halves and subsequent network disassociation. Protein Data Base ID Codes: PhoCl intact (green state) – 7DMX, PhoCl cleaved (red state) – 7DNA, PhoCl cleaved and dissociated (colorless state) – 7DNB, Coiled-coil - 1MZ9.