Biomedical Engineering Reference
In-Depth Information
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Figure 16.9
Binding (corrected data) of 500 pM cy3-labelled targets to different Areas on a 20-mer capture
probe spotted on glass (
Schultz et al., 2008
): (a) Area 1, (b) Area 2, (c) Area 3. 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.
These authors showed the vignetting effect, that is the distance of the Area (1, 2, or 3) from
the detector.
Figure 16.9a
shows that a dual-fractal analysis is required to adequately describe
the binding kinetics. The values of (a) the binding rate coefficient,
k
, and the fractal dimen-
sion,
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
Table 16.6
.
For a dual-fractal analysis, it is of interest to note that as the fractal dimension increases by a
factor of 2.11 from a value of
D
f1
equal to 1.1008 to
D
f2
equal to 2.3186, the binding rate
coefficient increases by a factor of 37.51 from a value of
k
1
equal to 0.2108 to
k
2
equal to
7.908. The changes in the degree of heterogeneity or the fractal dimension on the sensor sur-
face and in the binding rate coefficient are in the same direction.
Figure 16.9b
shows
the binding of 500 pM cy3-labelled target (raw data) to a 20-mer capture
probe immobilized on Area 2 (control) on the microarray biosensor (
Schultz et al., 2008
). It
shows, once again, that 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
