Supramolecular Protein Nanotubes with Optical Tunable Properties

Natural microtubules function through biochemical signal-tuned responsiveness. Building intelligent supramolecular assemblies that can emulate dynamic functions is a major challenge facing the field. We designed and synthesized a spiropyran-based inducing ligand that could assemble soybean agglutinin (SBA) into protein nanotubes. During the assembly, tuning of growth dynamics via the light signal resulted in a statistical difference in the average length. Moreover, the nanomechanical properties of the assembled tubes could be tuned via light signals in situ without interfering with the structural integrity, according to the results of liquid-phase Atomic Force Microscopy. Moreover, the SBA tetramer could be released from the assembly into the solution, with the morphology transition from tube to sheet, making a controlled release without harming the protein function. Spiropyran-based protein tubes hold promise for intelligent supramolecular assemblies.