Biomedical Engineering Reference
In-Depth Information
Platt et al. (2009a,b)
have recently demonstrated the “on-chip” evolution for fluorescently
tagged protein targets. They report that thrombin has been widely used in array experiments
(
Bock et al., 1992; Cho et al., 2006
). Thrombin was selected as a target due to its binding to
its motif,-GGN
2-5
GGT(A/T)GG.
Platt et al. (2009a,b)
reiterate that one should be able to
demonstrate or differentiate the actual protein binding events from nonspecific interactions.
That is the key (
Warren et al., 2006
). Platt et al. (2006) have demonstrated that biotin label-
ing followed by a posthybridization stage with a streptavidin-fluorophore conjugate has lower
nonspecific and background interactions.
Figure 15.9a
shows the binding of 16 nM thrombin in solution to aptamer (G4.04422; best
aptamer in generation 4) immobilized on a SA chip. A single-fractal analysis is adequate
to describe the binding and the dissociation kinetics. The values of (a) the binding rate coef-
ficient
k
and the fractal dimension
D
f
for a single-fractal analysis, and (b) the dissociation
20
30
25
15
20
10
15
10
5
5
0
0
0
100
200
300
400
500
600
700
0
100
200
300
400
500
600
700
B
Time (min)
A
Time (sec)
50
60
50
40
40
30
30
20
20
10
10
0
0
0
0
100
200
300
400
500
600
700
100
200
300
400
500
600
700
C
D
Time (min)
Time (min)
Figure 15.9
Binding and dissociation of different concentrations (in nM) of thrombin in solution to best
aptamer in generation 4 (G4.0422) immobilized on a SA chip (Platt et al.,
2009a,b
): (a) 16, (b) 32,
(c) 65, (d) 130.
