Bio Focus: 2D carbon-network nanomaterial shows promise as an antibacterial agent
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2D carbon-network nanomaterial shows promise as an antibacterial agent
(ii) Contact of GDYO with bacteria (i) GDYO dispersion in bacterial suspension
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structural relative to graphene and carbon nanotubes, graphidyne, has garnered significant attention over the past decade owing to its electrical and photocatalytic properties. A collaboration of researchers in China and the United States have now demonstrated a novel use for graphidyne, not as an energetic material, but as an antibacterial one. With evidence of antibacterial properties, graphidyne may find new applications in biomedical engineering. Graphidyne is a two-dimensional (2D) network of interconnected benzene rings, each joined together by diacetylenic linkages (two carbon-carbon triple bonds connected by a single carbon-carbon bond). Graphene, its well-known cousin, has been used for various applications including the formation of carbon nanotubes and has recently demonstrated antibacterial activity. Comparatively, graphidyne is a newer, more flexible material that is predicted to have superior electrical, catalytic, and energy-storing properties. “[W]e envisioned that graphidyne might [also] be a superior candidate in antibacterial-related fields,” says Alideertu Dong of Inner Mongolia University. To test the properties of this material, Dong and his colleagues formed oxidized graphidyne (GDYO) nanosheets. Oxidation is important because it allows better nanosheet dispersion in aqueous solutions and renders the material’s chemically inert surface active. Through a series of colony counting tests involving two types of bacteria, broadly classified as gram-positive (Staphylococcus aureus) and gramnegative (Escherichia coli), the research team found that GDYO possessed timedependent antibacterial effects which were significantly improved with exposure to light. Here, a number of interesting insights were revealed. GDYO was more effective against the gram-positive bacterial species (in which the cell walls are thick) than the gram-negative species (thin cell walls), demonstrating species-dependent efficacy.
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GDYO Light irradiation
Live bacteria
Dead bacteria
(iii) ROS generation on the surface of GDYO b
H2O2/H2SO4
GDY Nanosheets
GDYO Nanosheets
(a) Schematic illustration of the proposed mechanism of action for graphidyne oxide’s (GDYO) antibacterial effects. ROS is reactive oxygen species, a class of highly unstable oxygen species that detrimentally affects bacterial cells. (b) Illustration of the molecular structure of 2D graphidyne nanosheets and oxidized graphidyne (GDYO). Oxidation enables nanosheet dispersion in aqueous solutions and plays a critical role in GDYO’s antibacterial activity. Credit: iScience.
Also, compared to GDYO, graphidyne was significantly less effective against both species suggesting that chemical activation of the material’s surface is critical to its antibacterial effects. The fact that light improved GDYO’s effect is evidence of a potential photocatalytic mechanism. Previous characterization of graphene oxide’s
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