Synergistic Antibacterial Activity of Silver-Loaded Graphene Oxide towards <i>Staphylococcus Aureus</i> and <i>Escherichia Coli</i>

• Main Authors: Truong Thi Tuong Vi, Selvaraj Rajesh Kumar, Jong-Hwei Su Pang, Yu-Kuo Liu, Dave W. Chen, Shingjiang Jessie Lue
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Nanomaterials
• Subjects: antibacterial activity; graphene oxide; silver; synergistic; reactive oxygen species
• Online Access: https://www.mdpi.com/2079-4991/10/2/366

In this study, the physicochemical and surface properties of the GO&#8722;Ag composite promote a synergistic antibacterial effect towards both Gram-negative <i>Escherichia coli</i> (<i>E. coli</i>) and Gram-positive <i>Staphylococcus aureus</i> (<i>S. Aureus</i>) bacteria. GO&#8722;Ag NPs have a better bactericidal effect on <i>E. coli</i> (73%) and <i>S. Aureus</i> (98.5%) than pristine samples (pure Ag or GO). Transmission electron microscopy (TEM) confirms that the GO layers folded entire bacteria by attaching to the membrane through functional groups, while the Ag NPs penetrated the inner cell, thus damaging the cell membrane and leading to cell death. Cyclic voltammetry (CV) tests showed significant redox activity in GO&#8722;Ag NPs, enabling good catalytic performance towards H₂O₂ reduction. Strong reactive oxygen species (ROS) in GO&#8722;Ag NPs suggests that ROS might be associated with bactericidal activity. Therefore, the synergy between the physicochemical effect and ROS production of this material is proposed as the mechanism of its antibacterial activity.