Biomedical Engineering Reference
In-Depth Information
immunosensor array for the clinical immunophenotyping of acute leukemias. These authors
point out that immunophenotyping usually utilizes antibodies to recognize various differ-
entiated antigens of leukocytes. This, they state is a vitally important means for defining cer-
tain phenotype linkages or subsets of acute leukemias (
Traweek, 1993
;
Ba, 1998; Hoffman
et al., 2000
).
Zeng et al. (2006)
report that the QCM immunosensor is an active area of investigation for
bioassays. The QCM immunosensor exhibits high sensitivity and specificity, is simple to
use, and is cost-effective. These authors fabricated QCM crystal probes first with plasma-
polymerized film (PPF) and NPs (
Zeng et al., 2006
). Then, protein A (PA) was utilized to
orient the different immobilized leukemia-linkage-associated CD antibodies. This permitted
the formation of a QCM-based immunosensor array for probing the degrees of expression
of differentiated antigens on corresponding leukocytes. These authors used their QCM array
to immunophenotype 120 human bone marrow (BM) samples. They emphasize that their
proposed analytical procedure is direct and simple. Also, there are no multiple labeling and
separation steps.
Figure 8.2a
shows the binding of CD7 antigen in solution to the anti CD7 antibody
immobilized on the QCM immunosensor surface (
Zeng et al., 2006
). 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 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 8.1
. It is of interest to note that as the fractal dimension increases by a fac-
tor of 2.48 from a value of
D
f1
equal to 1.1436 to
D
f2
equal to 2.8362, the binding rate coef-
ficient increases by a factor of 7.99 from a value of
k
1
equal to 19.275 to
k
2
equal to 154.1.
It is seen that changes in the degree of heterogeneity or the fractal dimension on the QCM
surface and in the binding rate coefficient are in the same direction.
Figure 8.2b
shows the binding of CD5 antigen in solution to the anti CD5 antibody
immobilized on the QCM immunosensor surface (
Zeng et al., 2006
). 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 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 8.1
. It is of interest to note that as the fractal dimension increases by a fac-
tor of 2.76 from a value of
D
f1
equal to 0.8498 to
D
f2
equal to 2.3474, the binding rate co-
efficient increases by a factor of 5.63 from a value of
k
1
equal to 11.074 to
k
2
equal to 62.33.
It is seen that, once again, changes in the degree of heterogeneity or the fractal dimension
on the QCM surface and in the binding rate coefficient are in the same direction.
Figure 8.2c
shows the binding of CD3 antigen in solution to the anti CD3 antibody
immobilized on the QCM immunosensor surface (
Zeng et al., 2006
). A dual-fractal analysis
is required to adequately describe the binding kinetics. The values of (a) the binding rate
