Polyethylenimine-modified graphene oxide as a novel antibacterial agent and its synergistic effect with daptomycin for methicillin-resistant staphylococcus aureus

Abstract

An aqueous dispersion of polyethylenimine-modified graphene oxide (PEI-GO) was prepared via a one-step synthesis through an epoxy ring-opening reaction. PEI-GO exhibited bacterial growth inhibition activity on methicillin-resistant Staphylococcus aureus (MRSA) with a minimum inhibitory concentration as low as 8 μg mL-1. Time-kill curve assay and SYTOX Green assay showed the antibacterial activity and bacteria cell membrane permeability of PEI-GO, respectively. Most importantly, when PEI-GO was employed at 1-2 μg mL-1, a synergistic effect with daptomycin to resensitize daptomycin-resistant MRSA was revealed. A synergistic effect between PEI-GO and daptomycin provides a possible way to increase bacterial killing and reduce the development of daptomycin resistance. The antibacterial activity of PEI-GO is attributed to the damaged cell membrane caused by the sharp edge and chain structure of the PEI-GO nanosheets as well as the high density of amine groups present in the PEI chains. Our results indicate that PEI-GO dispersion has a great potential for clinical pathogenic bacteria treatment.