Pristine graphene, its derivatives, and composites have been widely reported to possess antibacterial properties. Most of the studies simulating the interaction between bacterial cell membranes and the surface of graphene have proposed that the graphene-induced bacterial cell death is caused either by (1) the insertion of blade-like graphene-based nanosheets or (2) the destructive extraction of lipid molecules by the presence of the lipophilic graphene. These simulation studies have, however, only take into account graphene-cell membrane interactions where the graphene is in a dispersed form. In this paper, we report the antimicrobial behavior of graphene sheet surfaces in an attempt to further advance the current knowledge pertaining to graphene cytotoxicity using both experimental and computer simulation approaches. Graphene nanofilms were fabricated to exhibit different edge lengths and different angles of orientation in the graphene sheets. These substrates were placed in contact with Pseudomonas aeruginosa and Staphylococcus aureus bacteria, where it was seen that these substrates exhibited variable bactericidal efficiency toward these two pathogenic bacteria. It was demonstrated that the density of the edges of the graphene was one of the principal parameters that contributed to the antibacterial behavior of the graphene nanosheet films. The study provides both experimental and theoretical evidence that the antibacterial behavior of graphene nanosheets arises from the formation of pores in the bacterial cell wall, causing a subsequent osmotic imbalance and cell death.
Single and few layer molybdenum disulfide (MoS2) was exfoliated from the bulk form through a liquid phase exfoliation procedure. Highly concentrated suspensions were prepared that were stabilized against reaggregation through adsorption of nonionic polymers to the sheet surface. These exfoliated particles showed strong photoluminescence at an energy of 1.97 eV which is in the visible-light region. These exfoliated MoS2 sheets were then used to catalyze the degradation of a model dye upon exposure to visible light.
Those surfactants which are easily synthesized, eco‐friendly, low cost, and able to produce high yields of graphene are crucial for large‐scale graphene manufacture and targeted applications of graphene. This study reports a curable surfactant based on benzoxazine that assists in both the exfoliation process in water with high yield as well as stabilizes the pristine graphene sheets against reaggregation. Freestanding and flexible graphene films are prepared through filtration and subsequent curing of the thermosetting benzoxazine surfactant at a moderate temperature, resulting in high strength as well as high electrical conductivity. Furthermore, graphene films loaded with this curable surfactant are easily transferred onto various substrates. The affinity of the graphene films with the substrate materials has been promoted by the thermal treatment to cure the surfactant. Once cured, the graphene film is highly durable and chemically resistant. In addition, the nature of the benzoxazine resin based surfactant endows this graphene film with excellent biocompatibility.
Lipid packing is intimately related to the geometry of the lipids and the forces that drive self-assembly. Here, the photothermal response of a cubic liquid-crystalline phase formed using phytantriol in the presence of low concentrations of pristine graphene was evaluated. Small-angle X-ray scattering showed the reversible phase changes from cubic to hexagonal to micellar due to localized heating through irradiation with near-infrared (NIR) light and back to cubic after cooling.
The one step fabrication of nanocomposite films of conducting polymers with 2D nanoparticles is investigated in this study. Specifically, the inclusion of nanomaterials (single layer graphene, single layer molybdenum disulfide) within PEDOT is achieved using the vapor phase polymerization (VPP) technique. This facile process allows for the formation of thin films of the order of less than 200 nm, which display a wide range of enhanced properties (mechanical, optical, and electrochemical). Herein, in a typical example with added graphene (<0.003% w/w), the in-plane modulus of the film is increased to 145 GPa (ca. 65% increase above PEDOT−Tos) without any decrease in light transmission or lowering of conductivity. Furthermore, the nanocomposite outperforms both the PEDOT−Tos film and a Pt substrate in the reduction of oxygen when acting as an air-electrode.
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