Biomedical Engineering Reference
In-Depth Information
1.2
PANI (reference)
Gly-Gly-His
1.0
H
N
+
H
N
0.8
+
N
H
N
H
N
H
0.6
n
PANI/Gly-Gly-His
0.4
PANI/Gly-Gly-His
(working)
0.2
10
1
10
2
10
3
10
4
10
5
10
6
10
7
Cu ion concentration (pM)
FIGURE 4.13
Left
: Covalent attachment of peptides to PANI chains.
Right
: Conductance (current) of a 50 nm-working junction
(with peptide-modified PANI) and a 50 nm-reference junction (without peptide) vs. Cu2
concentration. The bias
voltage across the junctions is 0.1 V, and the solution is drinking water containing Cu2+ of various concentrations.
Adapted from Zhang, H., Boussaad, S., Ly, N., Tao, N. J., C. Z., He, H. X., Tao, N. J. (2004). Magnetic field assisted
assembly of metal/polymer/metal junction sensors.
Appl. Phys. Lett
. 84: 133-135. With permission.
mechanically stable than their bulk cousins. Another challenge is posed by chemically syn-
thesized nanowires which are known to assemble into complex structures.
Even though there has been tremendous advancement in fabrication techniques of 1-D
nanostructures, there are still difficulties associated with the fabrication of these nanos-
tructures with well-controlled and consistent dimension, morphology, phase purity, and
chemical composition. Practical routes to large quantities of 1-D nanostructures from a
diversified range of raw materials rapidly and at reasonable cost is still a big challenge.
Environmental and health questions have been raised. At the present time products
derived from these emerging technologies are viewed by the public in a more demanding
perspective from the standpoint of safety and environmental impact. The potential for
exposure to some of these nanostructures will increase as the quantity and types used in
society grow. The studies reported by Hunter and coworkers [63] provided a first insight
into the in vivo toxicity of a specific type of manufactured SWNTs.
In spite of the numerous challenges, 1-D nanostructured materials offer unlimited
research opportunities. These techniques exceed capabilities of other methods such as
PCR [64] and micromechanical devices [65].
Acknowledgments
The authors thank DOD/DARPA/DMEA and US EPA for supporting studies on individ-
ually addressable biologically functionalized CP NWs array for label-free immunosensors.
References
1.
Schasfoort, R. B. M., Kooyman, R. P. H., Greve, J. (1990). A new approach to ImmunoFET
operation.
Biosens. Biolelectr.
5:103-124.
