3.4. Antibacterial assay
In this study, the bacterium E. coli was chosen as a test subject
due to its abundance in domestic waste water (Narmadha and
Mary Selvam Kavitha, 2013). The antibacterial activity of GSC
was studied at two different concentrations: 0.1 g and
0.2 g through the zone of inhibitions. Fig. 5 (a) and (b) show the
antibacterial activity at 0.1 g and 0.2 g of GSC respectively. An inhibition
zone of 8 mm was observed for 0.1 g of GSC. Increased
activity with higher inhibition zone of 20 mm was observed for
0.2 g of GSC.
This may be accounted by the membrane stress and oxidative
stress induced by the wrinkly, sharp edges and the nano-layers
observed in GSC. Venkateshwara Rao et al. (2013) has observed
strong antibacterial effect of graphene oxide against Klebsellia and
Staphylococus. Liu et al., has shown that graphene oxide inhibits the
growth of E. coli strongly. Membrane stress flattens the E. coli cell
causing loss of cellular integrity. This stimulates irreversible damage
to the cellwalls, effectively destroying the E. coli cells. Graphene
cytotoxicity studies cite oxidative stress also as a toxicity mechanism
of graphene.