Biology Reference
In-Depth Information
biosensor to assess in-vitro the viral infection of human foreskin fibro-
blasts with tosylate-doped PEDOT electrodes patterned on cyclic-olefin
copolymer (COC) substrate.
84
In-vivo neural recording have been also
carried out with poly(styrene sulfonate)-doped PEDOT microelectrodes
deposited on Parylene C substrate.
85
Owens monitored the gastrointesti-
nal epithelium disruption with an organic transistor.
86
Polyanilines have
been also micropatterned
87
and were further used for conductivity detec-
tion.
88
Finally, PDMS has also been mixed with carbon alone
89
or carbon
and oil
90
(oil reducing capacitive current) to form doped polymeric elec-
trodes for bioapplications. In the latter case, microelectrodes have been
patterned and thus used to detect catecholamine release from PC12 cells
by voltammetry.
Graphene is a unique atom-thick membrane of carbon atoms arranged
as a honey-comb crystal lattice. Compared to zero-dimensional nanoobjects
(nanoparticules and quantum dots) and one-dimensional nanostructures
(CNTs) and Si nanowires, a graphene sheet could represent an interest-
ing alternative due to the fact that it presents outstanding electrical and
mechanical properties
91
and that it could interact directly with much larger
biological samples, like cells and even tissues. For example, a graphene-
based transistor has been used to monitor cardiomyocyte electrical activ-
ity.
92
Concerning cell detection, it has been also used to detect single
bacteria,
93
and graphene functionalized with aptamers has been employed
to detect suspended cancer cells by impedancemetry.
94
Integrated detec-
tion of cell biomolecule release can also be carried out: assembly of sev-
eral layers of graphene sheet with perodixase (for biomolecule selectivity)
and extracellular matrix protein (for enhanced biocompatibility) have been
able to detect hydrogen peroxide release from living cells by voltamme-
t r y,
95
and patterned graphene oxide sheet integrated as the gate of an FET
have monitored the catecholamine release from neuroendocrine cells.
96
Recently, graphene-based electrochemical sensors have been implanted in-
vivo, on teeth, to monitor mouth bacterial activity wirelessly.
97
Interestingly,
by functionalizing graphene with gold nanoparticles (themselves func-
tionalized with calcium ions), graphene sheets have been wrapped around
single yeast cells.
98
Then, by interconnecting this graphene-cell complex
with gold electrodes, cell volume change caused by exposure to alcohol
has been electrochemically quantified. Various other chemical elements are
progressively integrated as electrode material, particularly for the reference
electrode, which for long time has been a technological bottleneck for fully
integrated electrochemical devices.
99,100
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