Biomedical Engineering Reference
In-Depth Information
100
80
60
40
20
0
0
20
40
Time (min)
60
80
Figure 11.7
Binding (hybridization) of SA-HRP (streptavidin horseradish peroxidase) in solution to a capture
probe on a QCM (quartz crystal microbalance) electrode along with a detection probe (
Feng et al.,
2007
). When only a solid line (--) is used then a single-fractal analysis applies. When both a dashed
(- - -) and a solid (--) line are used then the dashed line represents a single-fractal analysis and the
solid line represents a dual-fractal analysis.
Figure 11.7a
shows the binding of SA-HRP and DAB in solution to the capture probe
modified QCM electrode along with 1
m
M detection probe. A dual-fractal analysis is required
to adequately describe the binding kinetics. The values of (a) the binding rate coefficient,
k
, and the fractal dimension,
D
f
, for a single-fractal analysis, and (b) the binding rate
coefficients,
k
1
and
k
2
and the fractal dimensions, D
f1
and D
f2
, for a dual-fractal analysis
are given in
Tables 11.4
and
11.5
. It is of interest to note that for a dual-fractal analysis as
the fractal dimension increases by a factor of 3.51 from a value of
D
f1
equal to 0.7886 to
D
f2
equal to 2.7684, the binding rate coefficient increases by a factor of 41.96 from a value
of
k
1
equal to 1.0132 to
k
2
equal to 42.513.
Abad-Valle et al. (2007a,b
) recently used an electrochemical enzymatic genosensor to ana-
lyze DNA single-base mismatches. These authors report that electrochemical transducers
provide rapid and sensitive measurements. Besides, these devices are simple low cost,
and exhibit the potential to be miniaturized. Abad-Valle et al. (2005) further explain that
enzyme labels, due to their inherent amplification help permit an increase in assay sensitiv-
ity.
Caruana and Heller (1999)
used a soybean peroxidase label for detecting a single-base
mismatch in an 18-base oligonucleotide. Abad-Valle et al. (2005) had previously developed
an enzymatic electrochemical genosensor on gold films to analyze the selectivity of DNA
hybridization.
Abad-Valle et al. (2007a,b
) report that they have used a sequence of the
SARS (severe acute respiratory syndrome) coronavirus (CoV) as a target. This SARS
CoV is the causative agent of an atypical pneumonia. They further point out that it is essen-
tial to identify the SARS-CoV quickly and accurately owing to the rate of mortality of
patients.
