Abstract
This work reports on the preparation, characterization and antibacterial
activity of a nanocomposite formed from graphene oxide (GO) sheets
decorated with silver nanoparticles (GO-Ag). The GO-Ag nanocomposite was
prepared in the presence of AgNO3 and sodium citrate. The
physicochemical characterization was performed by UV-vis spectroscopy,
X-ray diffraction (XRD), thermogravimetric analysis (TGA), Raman
spectroscopy and transmission electron microscopy (TEM). The average
size of the silver nanoparticles anchored on the GO surface was 7.5 nm.
Oxidation debris fragments (a byproduct adsorbed on the GO surface) were
found to be crucial for the nucleation and growth of the silver
nanoparticles. The antibacterial activity of the GO and GO-Ag
nanocomposite against the microorganism Pseudomonas aeruginosa was
investigated using the standard counting plate methodology. The GO
dispersion showed no antibacterial activity against P. aeruginosa over
the concentration range investigated. On the other hand, the GO-Ag
nanocomposite displayed high biocidal activity with a minimum inhibitory
concentration ranging from 2.5 to 5.0 mu g/mL. The anti-biofilm activity
toward P. aeruginosa adhered on stainless steel surfaces was also
investigated. The results showed a 100% inhibition rate of the adhered
cells after exposure to the GO-Ag nanocomposite for one hour. To the
best of our knowledge, this work provides the first direct evidence that
GO-Ag nanocomposites can inhibit the growth of microbial adhered cells,
thus preventing the process of biofilm formation. These promising
results support the idea that GO-Ag nanocomposites may be applied as
antibacterial coatings material to prevent the development of biofilms
in food packaging and medical devices. (C) 2013 Elsevier B.V. All rights
reserved.
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