Biomedical Engineering Reference
In-Depth Information
The enzymes yielded NADH or H
2
O
2
in the presence of NAD+ and ethanol or
O
2
and glucose, respectively. As the CNTs were linked with those enzymes,
they could function as amperometric sensors for H
2
O
2
or O
2
detection.
CNT-based nano-electric devices not only could be used to detect small
chemical molecules, but they could be also applied in the area of biological
macromolecule analysis. CNT FETs could monitor the change in surface
charge when DNA was hybridised on the sensor surface. Star
et al.
29
reported
wrapping SWNTs using single-stranded DNA (ssDNA) by means of the
aromatic interactions between nucleotide bases and SWNTs. The ssDNA 5-
CCT AAT AAC AAT-3, when wrapped on an SWNT, could function as a capture
probe to detect the complementary DNA sequences. The match and mismatch
of the target DNA changed the transistor characteristics, such as G-Vg transfer
curves, and gave out obvious electric signals for accurate monitoring.
Moreover, CNT-based nano-sensors have been explored for highly
sensitive electronic detection of proteins, such as antibodies. Chen
et al.
30
Figure 7.4
(a) A nano-protein detector composed of a CNT-based transistor.
Functionalised CNT for speciically sensing (b) SA, (c) IgG and (d) mAbs. Reproduced
from Chen
et al.
30
with permission. Copyright (2003) National Academy of Sciences,
U.S.A.
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