Biomedical Engineering Reference
In-Depth Information
(
a
) Graphene
(
b
) Probe
(
c
) Wild
(
d
) Mutant
-
Z
i
(b)
(e)
(
e
) nc
(a)
(c)
(d)
Z
r
Figure 4.5
DNA biosensing on graphene platform and relative variation of charge
transfer resistance (modii ed from [18]).
detectable at the pM concentration level. h e same authors used a simi-
lar scheme to perform the impedimetric detection of DNA hybridization
on dif erent chemically modii ed graphene platforms containing dif erent
defect densities and amounts of oxygen-containing groups, namely graph-
ite oxide (GPO), graphene oxide (GO), thermally-reduced graphene oxide
(TR-GO) and electrochemically-reduced graphene oxide (ER-GO) [119].
h ese CMG materials were obtained from the oxidation of graphite to
graphite oxide and subsequent exfoliation to graphene oxide. h e latter
was electrochemically reduced to obtain ER-GO. h e thermal treatment
of graphite oxide led to TR-GO (see Figure 4.6). h e authors compared
the four CMGs as platforms for impedimetric genosensing, i nding that
graphene oxide provided the best ability to discriminate a complementary
sequence from one carrying a SNP.
h e same platforms were used by Bonanni
et al.
[121] to investigate the
utility of graphenes prepared by dif erent methods and carrying on their
surface various oxygen-containing groups, for the covalent functional-
ization with single-stranded DNA. h e functionalization was performed
via carbodiimide chemistry and a covalent bond was formed between the
amino linker of ssDNA probes and the carboxylic group present on the
graphene surface. h e platforms were then employed for the impedimetric
detection of DNA hybridization and polymorphism. h e best sensitivity
and reproducibility were obtained when using electrochemically-reduced
graphene oxide. On this platform, a higher amount of DNA probes was
immobilized, as also coni rmed by the chronocoulometry results. h ese
results were consistent with the surface characterization previously per-
formed by XPS in which a higher content of carboxylic group was found
in ER-GO.
