Biomedical Engineering Reference
In-Depth Information
0.012
1.4
0.01
1.2
1
0.008
0.8
0.006
0.6
0.004
0.4
0.002
0.2
0
0
0
500
1000
1500
Time (s)
2000
2500
3000
0
500
1000
1500
2000
B
A
Time (s)
Figure 11.6
Binding of 100 nM free-DNA in solution to a (a) noncomplementary and (b) a complementary 22
mer strand (bound DNA) immobilized via a phenylene-diisocyanate linker molecule on a glass
substrate (
Michel 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.
on a glass substrate (
Michel et al., 2007
). Adual-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
,fora
single-fractal analysis, and 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
Table 11.3
. It is of interest to note that for a dual-fractal
analysis, as the fractal dimension increases by a factor of 1.905 from a value of
D
f1
equal to 1.4592
to
D
f2
equal to 2.7794, the binding rate coefficient increases by a factor of 51.71 from a value of
k
1
equal to 0.00869 to
k
2
equal to 0.4462.
Also note that for the binding in the nonmatching (noncomplementary) case a single-fractal
analysis is adequate to describe the binding kinetics. However, for the matching (complemen-
tary) case a dual-fractal analysis is required to describe the binding kinetics. This would indi-
cate that, at least for this case, the binding of the matching (complementary) case is more
complicated than that of the nonmatching (noncomplementary) case. No explanation is
offered, at present, to help explain why this is the case.
Feng et al. (2007
) recently reported that single nucleotide polymorphisms (SNPs) are impor-
tant in clinical diagnostics, pathology detection, and genetic diseases. Lin et al. (2005) point
out that SNPs are point mutations that include the most-common genetic variation.
Wabuyele
et al. (2003)
have explained that quite a few genetic diseases and cancers are associated with
mutation in the sequence of particular genes.
Landegren et al. (1988)
initially used DNA
ligase for the detection of SNPs.
Feng et al. (2007)
have used the QCM technique coupled
with the DNA enzyme-based ligase reaction to sense a point mutation in a DNA target. These
authors used a signal amplification method for the quantitative detection of the target gene
that included the deposition of an insoluble product of 3,3-diaminobenzidine (DAB)
(
Karousis et al., 2002
) on the electrode supports mediated by SA-HRP conjugate.
