Graphene/CuO₂ Nanoshuttles with Controllable Release of Oxygen Nanobubbles Promoting Interruption of Bacterial Respiration

An oxygen nanoshuttle based on a reduced graphene oxide/copper peroxide (rGO/CuO2) nanocomposite has been presented to deliver in situ oxygen nanobubbles (O-2 NBs) for combating bacterial infections. In the presence of rGO, the solid source of oxygen (i.e., CuO2) was decomposed (in response to environmental conditions such as pH and temperature) into O-2 NBs in a more controllable and long-lasting trend (from 60 to 144 h). In a neutral buffer, the O-2 NBs experienced growth and collapse evolutions, creating a dynamic micro- nanoenvironment around the nanocomposite. In addition to effective battling against methicillin-resistant Staphylococcus aureus bacteria, the O-2 NBs demonstrated superior antibacterial properties on Gram-positive S. aureus to those on Gram-negative Escherichia coli bacteria, especially in the presence of rGO. In fact, the rGO contents could provide synergistic effects through harvesting some respiratory electrons (leading to striking interruption of the bacterial respiratory pathway) in one side and transferring them into the O-2 NBs, resulting in nanoscale reactive oxygen species (ROS) generation in another side. Moreover, near-infrared laser irradiation induced more damage to the cell membrane due to the synergistic effects of local heat elevation and catalyzing the release/collapse of NBs imposing mechanical disruptions. Our results show that the O-2-containing nanoshuttles can effectively be used as intelligent and controllable anti-infection nanorobots in upcoming graphene-based nanobiomedical applications.