The
design and engineering of high-performance antimicrobial agents
is critical for combating antibiotic resistance. In the present study,
a rapid and broad-spectrum bactericidal agent is developed based on
nanocomposites consisting of cobalt-doped zinc oxide (CoZnO) nanoparticles
and MoS2 nanosheets. The CoZnO/MoS2 nanocomposites
are prepared by a facile chemical precipitation method at controlled
CoZnO and MoS2 feeds. Scanning and transmission electron
microscopic measurements show that CoZnO nanoparticles (ca. 10 nm
in diameter) are clustered on the MoS2 nanosheet surface,
which facilitates the charge separation of the photo-generated electron–hole
pairs, leading to enhanced photodynamic antimicrobial activity. Antibacterial
assays in the dark show that the CoZnO/MoS2 nanocomposite
prepared at 30 μg of MoS2 feed (CoZnO/MoS2-30) exhibits the best performance among a series of samples, with
minimum inhibitory concentrations of 0.25, 0.8, and 1.8 mg mL–1 toward the Gram-negative bacterium Escherichia coli, Gram-positive bacterium Staphylococcus aureus and fungus Aspergillus
flavus, respectively. The antibacterial performance
is markedly enhanced under photoirradiation, where 94.0% inactivation
of E. coli is achieved with 20 μg
mL–1 CoZnO/MoS2-30 nanocomposite under
photoirradiation (15 W, 360 nm) for 5 min. The high antibacterial
activity can be ascribed to peroxidase-like photocatalytic activity
that is conducive to the generation of reactive oxygen species, as
evidenced in transmission electron microscopy, electron spin resonance,
and intracellular glutathione oxidation measurements. The results
of the present study highlight the significance of CoZnO/MoS2 nanocomposites as potent photodynamic antibacterial agents.