Biomedical Engineering Reference
In-Depth Information
Figure 7.5
Schematic illustration of well match (WM), C and A mismatch (CA) and G
and T mismatch DNA duplex bridging between CNT poles. Conductance decreased
when mismatch was introduced in the DNA duplex.
7.2.2.2.5
Microscope sensors
A potential important application of CNTs could be the materials for atomic
force scanning microscope probes. The small diameters of CNTs make them
ideal structures to be used as the tips for atomic force scanning. Both MWNTs
39
and SWNTs
40,41
could be used to produce tips of those microscopes. Hafner
et
al.
40
and Cheung
et al.
41
reported that it is possible to grow individual CNT
probe tips directly, with control over the orientation from the ends of silicon
tips. Those based on SWNTs showed very high-resolution tips with end radii
of 3-6 nm, in comparison with other commercial available tips, whose radii
are generally greater than 5-10 nm.
Another advantage of CNT-based microscope tips is their versatility
for chemical modiication, which may give them the ability to discriminate
between different chemical and biological objects. Wong
et al.
42
prepared
such a chemical force microscope by coupling the CNT tips with basic or
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