Biomedical Engineering Reference
In-Depth Information
Fig. 4.7 (a) Illustration of dsDNA translocation through the BLM connector pore. (b) Typical
current blockade events from dsDNA tranloscation through the nanopore. Insert: A magnified
current blockade event showing the current depth and the dwell time of translocation. Representa-
tive blockades caused by 45 pM double-stranded circular plasmid DNA without (c) and with
(d) DNase digestion. Figures reproduced with permissions from: (c-d) Ref. [
42
],
Nature
#
Publishing Group
one channel divided by the step size of the current for one connector insertion.
In the presence of dsDNA, the channel blockade percentage was centered at ~32%
(Fig.
4.8a
), which is consistent with the dimensions of the channel (3.6 nm diameter
at
its narrowest end) and dsDNA (~2 nm in diameter). That
is, blockade
2
2
%
100. Furthermore, each transient current block-
ade event was observed to be nearly identical as demonstrated by a sharp Gaussian
distribution (Fig.
4.8a
).
Another parameter is the dwell time (
¼½p ð
2
2
Þ
=p ð
3
:
6
2
Þ
t
p
) for DNA translocation events, which
represents the time taken by the DNA to translocate through the channel
(Fig.
4.8b
). The dwell time distribution follows an exponential decay function.
The peak dwell time represents the most probable event duration. For instance,
under
40 mV, the peak dwell time for 5 kbp dsDNA was 9.2 ms
and 22.1 ms, respectively, demonstrating that the dwell time of DNA translocation
was affected by applied voltage. In addition, shorter dwell times were observed
for shorter lengths of DNA, as shown in Fig
4.8b
comparing the dwell time for
35 bp and 5 kbp dsDNA.
75 mV and
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