Antimicrobial Activities of Zn-Doped CuO Microparticles Decorated on Polydopamine against Sensitive and Antibiotic-Resistant Bacteria

Abstract

A polydopamine (PDA) composite was synthesized by depositing Zn-doped CuO (Zn@CuO) particles on polydopamine by one-step ultrasonication. XPS, XRD, and FTIR confirmed the formation of spherical Zn@CuO on PDA with resulting diameters ranging from 1 to 5 μm. The PDA-Zn@CuO at 0.125–0.5 mg/mL exhibited a superior activity over Zn@CuO against sensitive and antibiotic-resistant bacteria. The Zn@CuO nanosized hybrid particles could penetrate the cell but interacted less effectively with bacterial biomolecules to provoke rapid cell lysis. PDA above 0.5 mg/mL also had a modest effect against Escherichia coli and Staphylococcus aureus. However, much higher PDA concentrations were required to restrict the flow of essential nutrients and wastes in and out of the cytoplasmic matrix and resulted in eventual cell death. The binding of PDA-Zn@CuO to bacteria played an important role in causing bacterial death, whereas reactive oxygen species (ROS) also effectively contributed to cell killing.