(361c) Initial Adhesion of Bacterial Cells on Surfaces Functionalized with Graphene Oxide: Insights from AFM-Based Single-Cell Force Spectroscopy

Graphene oxide (GO) is a one-atom thick, two-dimensional sheet of hexagonally arranged carbon atoms, decorated with carboxyl, hydroxyl, and epoxide functional groups. GO nanosheets possess exceptional physical and chemical properties (e.g., mechanical strength, high specific surface area, and colloidal stability), as well as antimicrobial properties against both gram-negative and -positive bacteria. Extensive research has been performed to explore the mechanisms underlying GO’s antibacterial activity. Yet, to date, a molecular-level understanding of the interaction between bacterial cell membranes and GO is largely lacking. Understanding the interactions of GO nanosheets with bacterial cell membranes is essential for the evaluation of GO’s environmental impacts, and to advance graphene-based environmental applications. In this study, we use atomic force microscopy-based single-cell force spectroscopy (AFM-SCFS) to preliminarily elucidate the interactions between single live bacterial cells and model surfaces functionalized with GO. Specifically, we quantify and compare the adhesive forces of a single bacterial cell onto model surfaces in which the spatial orientation of GO sheets (i.e., flat vs. randomly oriented) is varied. In addition, we investigate the role of natural organic matter (NOM) on cell-GO interactive forces. This investigation therefore provides insight into the influence of nanomaterial spatial orientation and solution chemistry on the behavior of GO in biological interfaces.