Biomedical Engineering Reference
In-Depth Information
Li et al. (2008)
report that aptamer-based electrochemical biosensors have been used to
detect proteins, and are based on aptamers that have been labeled using redox compounds
such as methylene blue (Cao et al., 2005). Catalysts such as HRP (horse radish peroxidase)
(
Monica et al., 2006
), and platinum nanoparticles (
Polsky et al., 2006
) have also been used
as signal-producing labels.
Li et al. (2005)
and
Liu et al. (2005)
report that direct electrochemical deposition of GNPs
onto an electrode surface is an efficient method of creating a nanomaterial platform for
DNA biosensor applications.
Li et al. (2008)
assert that thrombin plays a significant role in
a number of cardiovascular diseases and regulates quite a few processes in inflammation
and tissue repair at the vessel wall. The detection of thrombin is important with regard to
blood coagulation levels.
Zhang et al. (2009a,b
) have used an amplified electrochemical
aptasensor for thrombin based on the bio-barcode.
Li et al. (2008)
have developed a GNP
deposited GCE EIS biosensor to investigate aptamer-thrombin interactions.
Figure 6.4
shows the binding of 60 nM thrombin in solution to the EIS biosensor (
Li et al.,
2008
). A single-fractal analysis is adequate to describe the binding and the dissociation kinet-
ics. The values of the binding and the dissociation rate coefficients, and the corresponding
fractal dimension values are given in
Table 6.2
.
On comparing the binding and dissociation of 60 nM thrombin in solution to an EIS biosen-
sor (
Figure 6.4
;
Li et al., 2008
) with the binding of 20 nM thrombin in solution to the
biotinylated aptamer immobilized on a CMB chip (
Centi et al., 2008
), it is seen that in one
case there is binding and dissociation, and in the other just binding. On comparing the bind-
ing phase kinetics of both of these biosensor systems that are adequately described by a single-
fractal analysis, it is observed that as one goes from the CMB chip (
Centi et al., 2008
) to the
EIS biosensor (
Li et al., 2008
), the fractal dimension in the binding phase decreases by a
2500
2000
1500
1000
500
0
0
50
100
150
Time (min)
200
250
300
Figure 6.4
Binding of 60 nM thrombin in solution to an aptamer immobilized on a electrochemical impedance
spectroscopy (EIS) biosensor (
Li et al., 2008
).
