Biomedical Engineering Reference
In-Depth Information
a
10
4
10
3
cyclo(P-G)
3
TATp
DTPMPA
Y6
YPFF
10
2
10
1
10
0
10
-1
10
-2
1234
1234
1234
1234
1234
Sensor unit (N)
b
cyclo(P-G)
3
TATp
14
DTPMPA
Y6
YPFF
7
0
1
−
7
−
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
Sensor unit (N)
Fig. 13.12 Pattern-recognition differentiation of a variety of molecules. (a) Dwell time plot, and
(b) amplitude plot. The experiments were performed at +40 mV or
40 mV (
cis
at ground) with
1 M NaCl and 10 mM Tris-HCl (pH 7.5). Figure reprinted with permission from [
47
], Copyright
2008 IOP Publishing Ltd
To enhance the resolution and/or selectivity of nanopore sensors for multi-analyte
analysis, pattern-recognition nanopore sensor array technique was developed [
47
].
The proposed sensing device consisted of an array of at least two nanopores, each of
which had different functional groups (i.e., non-covalent bonding sites), ranging
from super hydrophobic to ultra hydrophilic, as well as having both positive and
negative charged surfaces. Thus, each individual pore of the sensor array was
different and reacted differently toward a compound. Furthermore, a parallel electric
circuit of on/off switches was employed to control which channel(s) to be monitored.
In this system, the collective responses of each individual component nanopore to a
compound produced a diagnostic pattern, which can serve as an analyte's signature
(Fig.
13.12
). This sensing principle is similar to the mammalian olfactory system
[
71
], and has been utilized in a variety of chemical sensors, including electronic nose
[
72
,
73
], to increase their differentiation resolution. With an increase in the
dimensionality of the sensing system, the nanopore pattern-recognition technology
has proven that it indeed provides an enhanced resolution for the differentiation of
analytes compared to a single-pore configuration, and allows identification of a target
analyte from a mixture or the potential for simultaneous detection.
13.6 Conclusions
Protein pore-based stochastic sensing technique has many advantages. These include
high sensitivity, rapid response, low cost, instrumental simplicity, ease of use, and low
false positive rate. Although the transition of protein pore technology to deployable
sensors for extended usage has been hindered by the fragility and the long-term
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