Synergistic Enhancement of Catalytic Activities in Ligand-Regulated Carbon Dots-Ferric Ion Nanozymes via UV-Enhanced Peroxidase-Oxidase.

Species of metal ions in carbon dots-metal ions complex nanozymes boost enzyme-mimicking activities. However, the relationship between ligand regulation of the catalytic activity of carbon dots-metal ions complex nanozymes still lacks clarity, which hinders the design of high-performance nanozymes. Herein, to understand the influence of ligands on nanozyme activities, three kinds of carbon dots-ferriic ions (CDs-Fe) nanozymes with three ligands, including allyltriphenylphosphonium bromide (TPP), 1-hydroxyethane-1,1-diphosphonic acid (HEDP), and diethylenetriaminepentaacetic acid (DTPA), are synthesized via sequential hydrothermal carbonization and coordination chemistry. The effects of ligand on peroxidase (POD)-mimicking and UV-induced oxidase-mimicking activities are then systematically evaluated. All CDs-Fe nanozymes exhibit dual POD-mimicking and UV-induced oxidase (OXD)-mimicking activities. Type of ligand significantly determines catalytic performance, for example, HEDPCDs-Fe exhibits the highest POD-mimicking activity (V 2.68 × 10 M s), meanwhile TPPCDs-Fe showing superior UV-induced OXD-mimicking activity (V 2.26 × 10 M s). Crucially, the synergistic effect of UV-enhanced POD-OXD is observed, where UV-induced processes enhanced POD-mimicking catalysis, motivating significantly improved reaction kinetics with lower K (1.05 mm) and higher V (5.17 × 10 M s). POD-mimicking activity with UV irradiation is 1.93 times that in the dark. Ligand-regulation strategy of CDs-Fe nanozyme based on coordination chemistry offers an idea to design and synthesize high catalytic activities of CDs-metal ions nanozymes.