Biomedical Engineering Reference
In-Depth Information
conjugate (
Loog et al., 2000; Viht et al., 2003
).
Viht et al. (2007)
point out that this type of
attachment does not lead to a significant loss in inhibitor potency.
Figure 4.1a
shows the binding and dissociation of 50 nM C
a
in solution to ARC-704
immobilized on a SPR biosensor chip surface. A dual-fractal is required to adequately
describe the binding kinetics. A single-fractal analysis is adequate to describe the dissociation
kinetics. The values of (a) the binding rate coefficient,
k
and the fractal dimension,
D
f
for a
single-fractal analysis, (b) the binding rate coefficients,
k
1
and
k
2
, and the fractal dimensions,
D
f1
and
D
f2
, and (c) the dissociation rate coefficient,
k
d
and the fractal dimension,
D
fd
, for a
single-fractal analysis are given in
Tables 4.1
and
4.2
.
The values of the binding rate coefficients and the fractal dimensions presented in
Table 4.1
were
obtained from a regression analysis using Corel Quattro Pro 8.0 (Corel Quatro Pro 8.0, 1007) to
model the data using Equations (4.1) and (4.3), wherein (Analyte
kt
(3
D
f
)/2
Receptor)
¼
k
1
t
(3
D
f1
)/2
and (Analyte
for a single-fractal analysis, and (Analyte
Receptor)
¼
Receptor)
¼
k
2
t
(3
D
f2
)/2
for a dual-fractal analysis, and (Analyte
k
d
t
(3
D
fd
)/2
for the dissociation
phase (eqn 4.2). The binding and the dissociation rate coefficient values presented in
Table 4.1
are within 95% confidence limits. For example, for the binding of 50 nM C
a
in solution to
ARC-704 immobilized on a SPR biosensor chip surface, and for a dual-fractal analysis,
the binding rate coefficient (
k
1
) value is 6.540
0.876. This 95% confidence limit indicates
that the
k
1
value lies between 5.664 and 7.416. This indicates that the value is precise and
significant.
Receptor)
¼
Figure 4.1b
shows the binding and dissociation of 25 nM C
a
in solution to ARC-704
immobilized on a SPR biosensor chip surface. Once again, a dual-fractal is required to
adequately describe the binding kinetics. A single-fractal analysis is adequate to describe
the dissociation kinetics. The values of (a) the binding rate coefficient,
k
and the fractal
dimension,
D
f
, for a single-fractal analysis, (b) the binding rate coefficients,
k
1
and
k
2
, and
the fractal dimensions,
D
f1
and
D
f2
, and (c) the dissociation rate coefficient,
k
d
and the fractal
dimension,
D
fd
for a single-fractal analysis are given in
Tables 4.1
and
4.2
.
In this case it is of interest to note that as the fractal dimension or the degree of heterogeneity
on the biosensor surface increases by a factor of 50.8% from a value of
D
f1
equal to 1.809 to
D
f2
equal to 2.729, the binding rate coefficient increases by a factor of 4.07 from a value of
k
1
equal to 2.831 to
k
2
equal to 11.53. Note that changes in the fractal dimension or the
degree of heterogeneity on the biosensor chip surface and in the binding rate coefficient
are in the same direction. In this case at least, an increase in the degree of heterogeneity or
the fractal dimension on the biosensor chip surface leads to an increase in the binding rate
coefficient.
Figure 4.1c
shows
the binding and dissociation of 10 nM C
a
in solution to ARC-704
immobilized on a SPR biosensor chip surface. Once again, a dual-fractal analysis is required
