Bioinspired Cu2MoS4 nanozymes as bifunctional catalysts with tunable enzyme-mimicking activity and enhanced bactericidal efficacy

Nanozymes are the nanomaterials mimicking enzymatic activity, offering advantages like stability, tunability, and multifunctionality over natural enzymes. Transition metal sulfide-based nanozymes, in particular, are special for their extraordinary catalytic and antimicrobial features. In this study, hydrothermally synthesized Cu 2 MoS 4 nanozymes were comprehensively characterized to evaluate their structural, morphological, and functional attributes. FE-SEM and TEM revealed uniform cubic nanoparticles (41 ± 2.5 nm) with high crystallinity, while EDX and XPS confirmed their stoichiometric composition (Cu + , Mo 6+ , S 2 ⁻). XRD analysis indicated a pure tetragonal phase, and FTIR identified metal-sulfur and metal-oxygen vibrations, suggesting catalytic surface functionality. The nanozymes exhibited excellent colloidal stability (zeta potential: −19.2 mV; PDI: 0.22; hydrodynamic size: ∼117.15 nm). Catalytically, they displayed intrinsic oxidase- and peroxidase-like activities, efficiently oxidizing TMB with or without H 2 O 2 . Kinetic studies revealed high efficiency (oxidase: K m = 0.422 mM, V max = 8.13 × 10 −8 M s −1 ; peroxidase: K m = 0.487 mM, V max = 12.5 × 10 −8 M s −1 ). Additionally, Cu 2 MoS 4 exhibited potent, dose-dependent antibacterial activity, with L. monocytogenes and B. cereus being highly susceptible (MIC: 30 µg/mL; MBC: 40 µg/mL), while S. aureus showed greater resistance. SEM imaging linked bactericidal effects to membrane damage induced by ROS from peroxidase-like activity. Electron paramagnetic resonance (EPR) spectroscopy also confirmed the predominant role of hydroxyl radicals, along with superoxide radicals in ROS-driven antibacterial mechanisms. These findings establish Cu 2 MoS 4 nanozymes as promising bifunctional catalysts with significant antibacterial potential, suitable for food safety applications.