Understanding the Antibacterial Mechanism of CuO Nanoparticles: Revealing the Route of Induced Oxidative Stress

TLDR

There is still a lack of definite knowledge regarding the interaction of CuO nanoparticles with bacteria and the possible permeation of the nanoparticles into bacterial cells. This study aimed to shed light on the size‑dependent antibacterial activity of CuO from microscale down to the small nanoscale. Lipid‑peroxidation assays and oxidative‑stress reporter strains confirmed the paradigm. CuO nanoparticles generate ROS when attached to bacterial cells, increasing intracellular oxidative stress and penetrating cells, thereby reconciling conflicting literature and suggesting sustainable CuO‑based antibacterial devices.

Abstract

Abstract To date, there is still a lack of definite knowledge regarding the interaction of CuO nanoparticles with bacteria and the possible permeation of the nanoparticles into bacterial cells. This study was aimed at shedding light on the size‐dependent (from the microscale down to the small nanoscale) antibacterial activity of CuO. The potent antibacterial activity of CuO nanoparticles was found to be due to ROS‐generation by the nanoparticles attached to the bacterial cells, which in turn provoked an enhancement of the intracellular oxidative stress. This paradigm was confirmed by several assays such as lipid peroxidation and reporter strains of oxidative stress. Furthermore, electron microscopy indicated that the small nanoparticles of CuO penetrated the cells. Collectively, the results reported herein may reconcile conflicting concepts in the literature concerning the antibacterial mechanism of CuO nanoparticles, as well as highlight the potential for developing sustainable CuO nanoparticles‐based devices for inhibiting bacterial infections.