Polymyxin B complexation enhances the antimicrobial potential of graphene oxide

Abstract

IntroductionThe antibacterial activity of graphene oxide (GO) has been widely explored and tested against various pathogenic bacterial strains. Although antimicrobial activity of GO against planktonic bacterial cells was demonstrated, its bacteriostatic and bactericidal effect alone is not sufficient to damage sedentary and well protected bacterial cells inside biofilms. Thus, to be utilized as an effective antibacterial agent, it is necessary to improve the antibacterial activity of GO either by integration with other nanomaterials or by attachment of antimicrobial agents. In this study, antimicrobial peptide polymyxin B (PMB) was adsorbed onto the surface of pristine GO and GO functionalized with triethylene glycol.MethodsThe antibacterial effects of the resulting materials were examined by evaluating minimum inhibitory concentration, minimum bactericidal concentration, time kill assay, live/dead viability staining and scanning electron microscopy.Results and discussionPMB adsorption significantly enhanced the bacteriostatic and bactericidal activity of GO against both planktonic cells and bacterial cells in biofilms. Furthermore, the coatings of PMB-adsorbed GO applied to catheter tubes strongly mitigated biofilm formation, by preventing bacterial adhesion and killing the bacterial cells that managed to attach. The presented results suggest that antibacterial peptide absorption can significantly enhance the antibacterial activity of GO and the resulting material can be effectively used not only against planktonic bacteria but also against infectious biofilms.

Graphene oxide/ε-poly-L-lysine self-assembled functionalized coatings improve the biocompatibility and antibacterial properties of titanium implants

“…Additionally, direct contact of GO with bacteria can activate mechanisms such as nano-knife ( Sun et al, 2020 ), encapsulation or capture ( Du et al, 2022 ), oxidative stress ( Liu et al, 2011 ), and has an evident antibacterial effect on both Gram-negative and Gram-positive bacteria ( Pulingam et al, 2019 ) . However, the inhibitory ability of GO to planktonic bacteria around the implant is limited ( Pandit et al, 2023 ). Furthermore, the antibacterial activity of GO is concentration-dependent, meaning that at high concentrations, GO may induce biotoxicity.…”