Graphene-based Multifunctional Agent And Mechanism Exploration

The development of new antibacterial agents which are highly effective towardsboth susceptible and drug resistance bacteria are of great interests. Nanotechnologyprovides a novel strategy for the development of new antibacterial agents due to highspecific surface area and reactive activity. Herein, we present a recyclablenanocomposite by growing both iron oxide nanoparticles (IONPs) and silvernanoparticles (AgNPs) on the surface of graphene oxide (GO), obtaining GO-IONP-Agnanocomposite as a novel multifunctional antibacterial material. Compared with AgNPswhich have been widely used as antibacterials agents, our GO-IONP-Ag shows muchhigher antibacterial efficiency not only towards susceptible Gram-negative bacteriumEscherichia coli (E. coli) and Gram-positive bacterium Staphylococcus aureus (S.aureus), but also for two types of drug resistant bacteria isolated from clinical samples.Taking advantages of its strong near-infrared (NIR) absorbance, photothermal treatmentis also conducted with GO-IONP-Ag, achieving a remarkable synergistic antibacterialeffect to inhibit drug resistant bacteria at a rather low concentration of this agent.Moreover, with magnetic IONPs existing in the composite, we can easily recycleGO-IONP-Ag by magnetic separation, allowing its repeated use. Given the aboveadvantages as well as its easy preparation and cheap cost, GO-IONP-Ag developed inthis work may find potential applications as a useful anti-bacterial agent in the areas ofhealthcare and environmental engineering.Compared with AgNPs, a systematic study of the antibacterial mechanism ofGO-IONP-Ag is conducted. Using scanning electron microscope and opticalmicroscope, the morphology and division changes of the E. coli and S.aureus areobtained. Results show that E. coli treated with silver nanoparticles or graphene-basednanocomposite can lead to damage of cell integrity, the difference is bacteria is mucheasier to be damaged by nanocomposite rather than silver nanopartiles at the same silvercontent. While no obvious cell integrity destruction are observed on AgNPs or GO-IONP-Ag treated S. aureus, further real-time monitoring of bacteria growthuncovered that both nanomaterials have inhibition effect toward gram positive S. aureus.This research shines light for the development of novel antibacterial agents.