Biomedical Engineering Reference
In-Depth Information
(
e
)
(
f
)
(
g
)
(
h
)
Figure 11.3
SEM images of nanoporous gold fabricated via electrochemical etching. h e
etching reaction was adjusted by ramping up the potential from 0 V to 40 V over 12 s (e,
f ), or from 0 V to 20 V over 24 s (g, h), respectively. All images are top views except in (h)
which shows a cross-sectional view. For (e) etching was carried out under static conditions,
while for (f-h), the solution was stirred during the etching process. h e inset in (g) shows an
image under low magnii cation [14]. (Reprinted with permission from [14].)
hybridization” process. h is reaction consists of a dual hybridization pro-
cess wherein at one end the target DNA hybridizes with the capture DNA
and at the other end with the reporter DNA. Development of specii c and
convenient DNA sensors that can detect ultralow concentrations of DNA
is necessary. Since DNA detection based on traditional methods such as
membrane blots and gel electrophoresis is rather slow and labor-intensive,
emerging new amplii cation strategies will be very promising for specii c
nucleic acid detection.
Because of high ai nity of sulfur for gold, thiolated DNA sequences can
be strongly bound to the gold surface, and this fact makes gold a promising
material in the DNA sensors i eld. Owing to its unique properties such as
high surface-to-volume ratio, stability, and suitable biocompatibility, NPG
seems to be an ideal material for immobilizing capture DNA for the fabri-
cation of target DNA sensors.
11.3.1
NPG-Based DNA Sensors
h e i rst NPG-based electrochemical DNA sensor was introduced in
2008 [33]. A NPG electrode was fabricated using a dealloying process,
