Graphene: Applications in Environmental Remediation and Sensing - Aquananotechnology: Global Prospects - page 696

Various graphene-based composites have been reported to have high antibacterial
activity. A highly water-soluble composite composed of brilliant blue (BB, a common
colorant), RGO, and tetradecyltriphenylphosphonium bromide having high antibacterial
activity was reported by Cai et al. 140 The composite was active against both gram-positive
and gram-negative bacteria (Figure 34.3a through h). Silver NP-graphene hybrids with
enhanced antibacterial activity are also reported. 141-145 An interesting strategy to create a
highly adhesive antibacterial material, inspired from mussels and their ability to attach
on to diverse surfaces, was reported by Zhang et al. 146 They synthesized a composite con-
sisting of Ag NPs, polydopamine, and GO sheets. This hybrid material exhibited strong
antibacterial properties to both gram-negative and gram-positive bacteria due to the syn-
ergistic effect of GO and Ag NPs. 146 Sreeprasad et al. 147 leveraged the rich abundance of
functional groups on the GO surface to anchor an antibacterial biopolymer chitosan and
an antibacterial iron-binding protein (lactoferrin) and fabricated a luminescent multifunc-
tional composite. The synergetic effect of different materials incorporated resulted in a
highly antibacterial composite. The composite showed a tendency to form self-standing
ilms that can aid in coating this composite onto suitable substrates (Figure 34.3i and j).

Outer membrane

(a) (b) (c) (d)

S. aureus BB-RGO-TTP-2

0.5 µm 0.5 µm 0.5 µm 0.2 µm

(e) (f) (g) (h)

E. coli

Outer
membrane

BB-RGO-
TTP-2

0.5 µm 0.5 µm 0.5 µm 0.2 µm

(i) Visible light
GO-LF-Ch

(j)

UV light

Initial
After 24 h

3

2.5

2

1.5

1

GO-Au@LF-Ch

0.5

0

IC Lf Ch GO RGO GO-Lf RGO-

Lf

GO-
Ch-Lf

RGO-
Ch-Lf

GO-
Ch-AuLf

RGO-
Ch-AuLf

Added materials in growth medium

FIGURE 34.3
TEM illustrating the antibacterial activity of brilliant blue/RGO/quaternary phosphonium salt composite (BB-
RGO-TTP) on S. aureus cell (a through d) and E. coli cells (e through h). The damage imparted to the outer
membrane is visible in (b) and (h). (Adapted from Cai, X. et al., Langmuir , 27, 7828, 2011. With permission.)
(i) Photographs of the composite ilms under visible and UV light. (j) Comparison of antibacterial activity of
different materials tested in the study. (Adapted from Sreeprasad, T.S. et al., ACS Appl. Mater. Interfaces , 3, 2643,
2011. With permission.)