Environmental Engineering Reference
In-Depth Information
12.6.5 FeO 4 /C 12 Nanostructures and 2-((4-ethyl-
phenoxy) methyl)-N-(substituted-phenyl
carbamothioyl)-benzamides
Antipathogenic surface coating nanol uid which was obtained by com-
bining FeO 4 /C 12 nanostructures and 2-((4-ethylphenoxy)metyl)-N-
(substituted-phenylcarbamothioyl)-benzamides, showed an improved
resistance to Staphylococcus aureus ATCC 25923 and Pseudomonas aeru-
ginosa ATCC 27853 in vitro bioi lm development. h is was demonstrated
by the viable cell counts of bioi lm-embedded bacterial cells and by scan-
ning electron microscopy examination of the colonized surface. h e
nanol uid proved to be noncytotoxic and did not inl uence the eukaryotic
cell cycle [64].
12.6.6 GrapheneNanosheets
h e impact of graphene-based materials on health and the environment
needs to be thoroughly evaluated before their potential applications.
Graphene has strong cytotoxicity toward bacteria. To better understand
its antimicrobial mechanism, many researchers compared the antibacterial
activity of four types of graphene-based materials (graphite Gt), graphite
oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO))
toward a bacterial model— Escherichia coli .
Under similar concentration and incubation conditions, GO dispersion
shows the highest antibacterial activity, sequentially followed by rGO, Gt
and GtO. Scanning electron microscope (SEM) and dynamic light scat-
tering analyses show that GO aggregates have the smallest average size
among the four types of materials. Scanning electron microscope images
show that direct contact with graphene nanosheets disrupts cell mem-
brane. No superoxide anion (O 2 •- )-induced reactive oxygen species (ROS)
production is detected. However, the four types of materials can oxidize
glutathione, which serves as redox state mediator in bacteria. Conductive
rGO and Gt have higher oxidation capacities than insulating GO and GtO.
Results suggest that antimicrobial actions are contributed by both mem-
brane and oxidation stress. h is study proposes that a three-step antimi-
crobial mechanism, previously used for carbon nanotubes, is applicable to
graphene-based materials. It includes initial cell deposition on graphene-
based materials, membrane stress caused by direct contact with sharp
nanosheets, and the ensuing superoxide anion-independent oxidation.
It envisions that physicochemical properties of graphene-based materi-
als, such as density of functional groups, size, and conductivity, can be
Search WWH ::




Custom Search