Biomedical Engineering Reference
In-Depth Information
70
100
60
80
50
60
40
30
40
20
20
10
0
0
0
10
20
30
40
50
60
0
10
20
30
40
B
A
Time (min)
Time (min)
Figure 15.8
(a) Binding of 280 nM transcription factor (rhSP1) in SP1 binding buffer on a microcantilever array
(
Huber et al., 2006
). (b) Binding of 400 nM transcription factor rhNF-
BinN-
B binding buffer to
k
k
SP1 binding on a microcantilever array (
Huber et al., 2006
).
to 33.166. Once again, an increase in the degree of heterogeneity or the fractal dimension on
the cantilever array (biosensor) surface leads to an increase in the binding rate coefficient.
Figure 15.8a
shows the binding of 280 nM rhSP1 in SP1 binding buffer to the cantilever array
(
Huber et al., 2006
). A single-fractal analysis is adequate to describe the binding kinetics.
The values of the binding rate coefficient
k
and the fractal dimension
D
f
for a single-fractal
analysis are given in
Table 15.5
.
Figure 15.8b
shows the binding of 400 NF-
k
B in NF-
k
B binding buffer to the cantilever
array (
Huber et al., 2006
). A single-fractal analysis is adequate to describe the binding
kinetics. The values of the binding rate coefficient
k
and the fractal dimension
D
f
for a
single-fractal analysis are given in
Table 15.5
.
If one were permitted to compare the results in Figures 15.8a and b (same cantilever, different
analytes), then a decrease in the fractal dimension by a factor of 1.46 from a value of
D
f
equal
to 2.3718 (200 nM rhSP1) to
D
f
equalto1.6270(400nMrhNF-
k
B) leads to a decrease in the bind-
ing rate coefficient by a factor of 3.26 from a value of
k
equal to 18.843 to
k
equal to 5.786.
Changes in the binding rate coefficient and in the fractal dimension are in the same direction.
Platt et al. (2009a,b)
have recently analyzed aptamer evolution for array-based diagnostics.
These authors report that aptamers are oligonucleotides that may bind to target ligands. Their
affinities are comparable to those of antibodies.
Bunka and Stockley (2006)
indicate that
aptamers have found applications ranging from biosensors to therapeutics.
Balamurugan
et al., 2008
) indicate that an “on-chip” optimization procedure is often required that involves
immobilization and tethering strategies.
