Biomedical Engineering Reference
In-Depth Information
factor of 1.32 from a value of
D
f
equal to 2.38632 to
D
f
equal to 1.810, and the corresponding
binding rate coefficient increases by a factor of 1.48 from a value of
k
equal to 83.044 to
k
equal to 122.88. In this case, a lower fractal dimension leads to a higher binding rate coeffi-
cient. This is contrary to the general trend presented in the different chapters throughout the
book. However, one should bear in mind that we are comparing and analyzing the perfor-
mance of two different biosensors which are detecting the same analyte (albeit with different
concentrations; 20 and 60 nm).
Yang et al. (2009)
have recently developed an ultrasensitive enhanced CL enzyme immuno-
assay for detecting AFP which was amplified by double-codified GNP labels. Their method
used 4-(4
0
-iodo) phenylphenol (IPPI) as a signal amplifier and double-codified GNP
(DC-AuNPs) labels modified by HRP-conjugated anti-AFP which were used for signal
amplification.
Yang et al. (2009)
report that gold nanoparticles (AuNPs) have been used in bioassays (
Rossi
and Mirkin, 2005; Ao et al., 2006; Chen and Zu, 2007; Gomez-Henz et al., 2008; Selvaraju
et al., 2008
).
Yang et al. (2009)
also point out that owing to the advantages of the CL tech-
nique that includes rapid detection, simple instrumentation, and a wide dynamic range it has
been used as a detection technique in biotechnology, pharmacology, molecular biology, and
in the environmental area (
Kuruoda et al., 2000; Konty et al., 2005
;
Elzbag et al., 2008
; Zhou
et al., 2008).
Yang et al. (2009)
have developed an ultrasensitive CL assay using IPP as a signal enhancer
and double-codified gold nanopaticle labels for further signal amplification to detect AFP
which is a tumor marker for the management of heptocellular carcinoma.
Figure 6.5a
shows the binding of AFP in the presence of IPP in solution to their ultrasensitive
enhanced CL enzyme biosensor using double-codified GNP labels as amplification agents.
A single-fractal analysis is adequate to describe the binding kinetics. A dual-fractal analysis
is required to adequately describe the dissociation kinetics. The values of (a) the binding
rate coefficient,
k
, and the fractal dimension,
D
f
, for a single-fractal analysis, and (c) the dis-
sociation rate coefficients,
k
d1
and
k
d2
, and the fractal dimensions,
D
fd1
and
D
fd2
, for a dual-
fractal analysis are given in
Tables 6.3
and
6.4
.
Figure 6.5b
shows the binding of AFP in the presence of PIP (
p
-iodophenol) in solution to
their ultrasensitive enhanced CL enzyme biosensor using double-codified GNP labels as
amplification agents. A dual-fractal analysis 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 analy-
sis, (b) the binding rate coefficients,
k
1
and
k
2
, and the fractal dimensions,
D
f1
and
D
f2
, for a
dual-fractal analysis, and (c) the dissociation rate coefficient,
k
d
, and the fractal dimension,
D
fd
, for a single-fractal analysis are given in
Tables 6.3
and
6.4
.
