Light-fuelled transport of large dendrimers and proteins.

This work presents a facile water-based supramolecular approach for light-induced surface patterning. The method is based upon azobenzene-functionalized high-molecular weight triazine dendrimers up to generation 9, demonstrating that even very large globular supramolecular complexes can be made to move in response to light. We also demonstrate light-fuelled macroscopic movements in native biomolecules, showing that complexes of apoferritin protein and azobenzene can effectively form light-induced surface patterns. Fundamentally, the results establish that thin films comprising both flexible and rigid globular particles of large diameter can be moved with light, whereas the presented material concepts offer new possibilities for the yet marginally explored biological applications of azobenzene surface patterning.

Light-Driven Surface Patterning of Supramolecular Polymers with Extremely Low Concentration of Photoactive Molecules.

Light-induced surface patterning in azobenzene-containing polymers and other materials is a widely studied phenomenon with possible applications in fields ranging from photonics to biology. Yet, the fundamental understanding of this purely photodriven mass transport remains inadequate, and existing literature fails to define a threshold chromophore content for mass transport to occur, if such a limit exists. This letter presents a systematic study of the relationship between chromophore concentration and mass transport using hydrogen-bonded polymer-azobenzene complexes, in which the chromophore concentration can be freely adjusted while keeping the polymer backbone unchanged. Essentially, we demonstrate that effective surface patterning can be induced even at an extremely low chromophore content of 1 mol %, when only every tenth polymer chain carries a single azobenzene molecular motor. Importantly, the results highlight the extraordinary photomechanical power of azobenzene and contribute to the fundamental understanding of the light-induced motions.