Photo-Switched Catalytic Amyloids

Light-mediated assembly of catalytic agents furnishes powerful means for spatiotemporal control of chemical reactions. Here, we demonstrate photo-switched hierarchical assembly of catalytic amyloid fibrils, through mixing an amphiphilic cross-ß peptide with a merocyanine photo-switch. The peptide monomers, comprising phenylalanine-lysine repeats, do not self-assemble in water because of the electrostatic repulsion between the positively charged lysine side chains; however, upon light-induced merocyanine-spiropyran transformation, amyloid fibrils were formed. Interestingly, increasing the mole ratio between the merocyanine photo-switch and the peptide gave rise to a remarkable assembly of aligned elongated fibrils. The process was fully reversible as light turn-off resulted in fibril disintegration. Notably, the photoinduced amyloid fibrils catalyzed hydrolysis of β-lactam antibiotics, offering a platform for light-mediated degradation of antibiotic pollutants in water. Microscopic and spectroscopic experiments reveal that the photoinduced transient catalytic amyloids were likely formed through π-π interactions between the spiropyran moieties and the aromatic residues of the phenylalanines, while electrostatic interactions between the negative sulfonates and lysine sidechains on the fibrils' surface were responsible for the macroscale alignment. The amyloid-merocyanine system represents a new concept for light-regulated assembly of catalytic amyloids, which may have also played a role in prebiotic evolution processes.