Iron–Copper Single-Atom Nanozyme for Enhanced Synergistic Antibacterial Activity

Abstract

The escalating phenomenon of bacterial resistance has precipitated the exacerbation of maladies attributable to microbial infections, constituting a substantial menace to human health. Nanozymes can catalyze the production of large quantities of reactive oxygen species (ROS) and then destroy bacterial cells. Nevertheless, most nanozymes require H₂O₂, photothermal, and acidic environments to elicit an effective antibacterial response. In this study, a Fe–Cu bimetallic single-atom nanozyme (FeCu-SAN-SO₄²^-) was synthesized by high-temperature pyrolysis and sulfation using an environmentally friendly Cu-FeMOF as a precursor. The resulting FeCu-SAN-SO₄²^- exhibited excellent oxidase (OXD)-like activity due to the synergistic effect of Fe–Cu dual sites, the high specific surface area (202 m² g^–1), and mesopore distribution (11.08 nm). FeCu-SAN-SO₄²^- also overcame the pH limitation by introducing Brønsted acidic sites and demonstrated excellent temperature tolerance and storage stability compared with natural enzymes. At a concentration of 0.1 mg mL^–1, the killing rate against four strains of E. coli, S. aureus, A. hydrophila, and A. tarda reached a level exceeding 90% without needing external conditions. The high antibacterial efficacy of FeCu-SAN-SO₄²^- was mainly attributed to its efficient generation of ROS, predominantly O₂^–• and •OH radicals. These ROS further deprive electrons of bacterial cellular components, causing irreversible oxidative stress. This work provides an effective antimicrobial agent by enhancing the environmental tolerance of nanozymes, which has great potential for food preservation and clinical applications.