The ongoing spread of multidrug-resistant bacteria over the past few decades necessitates
collateral efforts to develop new classes of antibacterial agents with different mechanisms
of action. The utilization of graphene nanosheets has recently gained attention with this
respect. Herein, we have synthesized and tested the antibacterial activity of an array of
graphene materials covalently functionalized with hydroxyl-, amine-, or carboxylcontaining
groups. Fourier transform infrared spectroscopy, and transmission electron
microscopy confirmed successful functionalization of the few-layer graphene (FLG). The
percentage of weight loss was measured by thermogravimetric analysis, which was found
to be 22%, 23%, and 37% for FLG-TEG-OH, FLG-NH2 and FLG-DEG-COOH,
respectively. In comparison with pristine graphene sheets, the functionalized few-layer
graphene (f-FLG) materials gained an adequate dispersibility in water as confirmed by
zeta potential analysis. Moreover, a significant improvement in the antibacterial activity
against Staphylococcus aureus and Escherichia coli, where all f-FLG compounds were
able to suppress bacterial growth, with a complete suppression achieved by FLG-DEGCOOH.
The minimum inhibitory concentration (MIC) was 250 μg/ml for both FLGTEG-
OH and FLG-NH2, while it was 125 μg/ml for FLG-DEG-COOH. Glutathione
oxidation test demonstrated an oxidative stress activity by all f-FLG compounds.
However, FLG-DEG-COOH demonstrated the highest reduction in glutathione activity.
FLG-DEG-COOH and FLG-TEG-OH showed adequate biocompatibility and
hemocompatibility. The chemical functionalization of graphene might be a step towards
the foundation of an effective class of antimicrobial agents.