Microwave hydrothermal synthesis and antibacterial activity of cocklebur-shaped Cu4O3 microparticles

In this work, cocklebur-shaped Cu 4 O 3 microstructure was synthesized by microwave-assisted hydrothermal reduction. The product obtained under microwave heating at a low-power setting for five min has a typical Xanthium-like morphology of 1.0 [Formula: see text]m × 1.5 [Formula: see text]m with uniform spines on the surface. The tetragonal crystalline and mixed valence of copper in the materials were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy (XPS) analysis, respectively. The high antibacterial activity toward the test strains was validated by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) test (156.25 mg L[Formula: see text] and 312.5 mg L[Formula: see text] for Escherichia coli, 78.12 mg L[Formula: see text] and 156.25 mg L[Formula: see text] for Staphylococcus aureus) and shake-flask inactivation experiments. The results of the free radical quenching test coupled with reactive oxygen species (ROS) detection with electron spin resonance (ESR) trapping prove that the antibacterial activity is mainly from the singlet oxygen generated in the suspension.