Long-term antibacterial stable reduced graphene oxide nanocomposites loaded with cuprous oxide nanoparticles

Stable reduced graphene oxide-cuprous oxide (rGO-Cu₂O) nanocomposites with long-term antibacterial activities were prepared by reducing copper sulfate supported on GO using ascorbic acid as reducing agent in the presence of polyethylene glycol (PEG) and sodium hydroxide at room temperature. The rGO provided a protective barrier for Cu₂O, preventing Cu₂O from reacting with external solution to leach copper ions too quickly. Meanwhile, the rGO also promoted the separation of photoexcited charge carriers of Cu₂O nanoparticles to enhance the oxidative stress reactive and protected Cu₂O from falling apart in the phosphate buffered solution (PBS) solution to prolong the generation time of reactive oxygen species (ROS). More importantly, the large specific surface area of rGO improved the dispersibility of Cu₂O by electrostatic interaction. The synergistic effect of sustained release of copper ions, elevated ROS production ability and uniform dispersion of rGO-Cu₂O nanocomposites resulted in the excellent antibacterial activities of rGO-Cu₂O nanocomposites against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) which were maintained around 70% and 65% and were increased by 40% and 35% compared with free Cu₂O after immersing 30 days in PBS solutions.