title: Antibacterial Activities of Graphene Oxide-Molybdenum Disulfide Nanocomposite Films.
abstract: Two-dimensional (2D) nanomaterials, such as graphene-based materials and transition metal dichalcogenide (TMD) nanosheets, are promising materials for biomedical applications owing to their remarkable cytocompatibility and physicochemical properties. On the basis of their potent antibacterial properties, 2D materials have potential as antibacterial films, wherein the 2D nanosheets are immobilized on the surface and the bacteria may contact with the basal planes of 2D nanosheets dominantly rather than contact with the sharp edges of nanosheets. To address these points, in this study, we prepared an effective antibacterial surface consisting of representative 2D materials, i.e., graphene oxide (GO) and molybdenum disulfide (MoS2), formed into nanosheets on a transparent substrate for real device applications. The antimicrobial properties of the GO-MoS2nanocomposite surface toward the Gram-negative bacteria Escherichia coli were investigated, and the GO-MoS2nanocomposite exhibited enhanced antimicrobial effects with increased glutathione oxidation capacity and partial conductivity. Furthermore, direct imaging of continuous morphological destruction in the individual bacterial cells having contacts with the GO-MoS2nanocomposite surface was characterized by holotomographic (HT) microscopy, which could be used to detect the refractive index (RI) distribution of each voxel in bacterial cell and reconstruct the three-dimensional (3D) mapping images of bacteria. In this regard, the decreases in both the volume (67.2%) and the dry mass (78.8%) of bacterial cells that came in contact with the surface for 80 min were quantitatively measured, and releasing of intracellular components mediated by membrane and oxidative stress was observed. Our findings provided new insights into the antibacterial properties of 2D nanocomposite film with label-free tracing of bacterial cell which improve our understanding of antimicrobial activities and opened a window for the 2D nanocomposite as a practical antibacterial film in biomedical applications.
authors.forename: Tae In
authors.initials: TI
authors.lastname: Kim
authors.forename: Buki
authors.identifier: http://orcid.org/0000-0002-7860-0458
authors.initials: B
authors.lastname: Kwon
authors.affiliation: Department of Physics, University of Cambridge , Cambridge, CB3 0HE, United Kingdom.
authors.forename: Jonghee
authors.initials: J
authors.lastname: Yoon
authors.forename: Ick-Joon
authors.initials: IJ
authors.lastname: Park
authors.forename: Gyeong Sook
authors.initials: GS
authors.lastname: Bang
authors.affiliation: TOMOCUBE, Incorporated, Daejeon 34141, Republic of Korea.
authors.forename: YongKeun
authors.identifier: http://orcid.org/0000-0003-0528-6661
authors.initials: Y
authors.lastname: Park
authors.forename: Yeon-Soo
authors.initials: YS
authors.lastname: Seo
authors.forename: Sung-Yool
authors.identifier: http://orcid.org/0000-0002-0960-7146
authors.initials: SY
authors.lastname: Choi
keywords: antibacterial activity; antibacterial film; graphene oxide; molybdenum disulfide; oxidative stress