A Tailorable Metal-Free Supramolecular Oxidase Equivalent with Photoswitchable Functions

Enzyme mimetics with superior enzyme-like catalytic properties have garnered significant attention due to robust catalytic performance, high operational stability, facile synthesis, cost-effectiveness, and versatility. Among these, light-activated enzyme mimics are particularly promising for applications with on-demand activation, allowing precise regulation of catalytic activity. However, most of the existing systems rely on metal ions as catalytic centers, restricting their practical applications due to systemic toxicity and high cost. This study showcases robust and light-activatable oxidase mimics, known as suprazyme, using organic molecule-based supramolecular materials. Herein, benzohydrazide-based molecules self-assemble into supramolecular fibers, with easy tailorability using structure modulation. The resulting extended excited-state lifetime of the assemblies leads to higher concentrations of superoxide anions, with consequent enhanced oxidase activity. These enzyme mimics utilize dioxygen as the oxidant source, eliminating the need for harmful hydrogen peroxide in the case of other oxidoreductases. Besides robust environmental stability against harsh conditions and recyclability, the suprazyme exhibits superior catalytic activity controlled by light. Moreover, the suprazyme displays efficient antimicrobial activity against Gram-positive and Gram-negative strains, which is precisely regulated by light irradiation. Overall, a new metal-free suprazyme with improved light-activated oxidase-like activity is demonstrated with tailorable catalysis that offers effective synthetic enzymes suitable for diverse biomedical applications.