Biomedical Engineering Reference
In-Depth Information
Table 16.4: Binding rate coefficients and fractal dimensions for the binding of the target in
solution to the LNB-based biosensor (
Martinez et al., 2009
).
Analyte/Receptor
k
k
1
k
2
D
f
D
f1
D
f2
Target/LNB-based
biosensor
4.6647
0.6508 3.878
0.517 5.791
0.107 1.9346
1.406
0.1824
2.3538
0.095
0.0456
of 1.49 from a value of
k
1
equal to 3.878 to
k
2
equal to 5.791. This is almost a linear increase
or close to it.
Schultz et al. (2008)
recently developed a novel fluorescence-based array biosensor for field
applications, such as environmental monitoring. It is based on DNA hybridization assays.
The intent was to meet the demand for a portable, automated, and easy-to-maintain biosensor
that permitted the continuous monitoring of surface reactions. Their sensor is based on a
microscopic slide that serves as a transducer as well as a biological array sensor.
Schultz et al. (2008)
have pointed out the need for integrated microdevices that combine
integrated circuit elements, electro-optic excitations/detection systems, and bioreceptor
probes (Malakios et al., 2004;
Ito et al., 1996
). Schultz et al. (2005) explain that fluorescence
based assays predominate the microarray field owing to their better sensitivity and specific-
ity, and decreased background signals when compared with free-label assays (
Baldini and
Giannetti, 2005
).
Karpf et al. (1988)
first demonstrated the use of hybridization assays. Later
Eggers et al.
(1994)
applied this to a CCD chip with radio-active fluorescent labeling of target molecules.
Vo-Dinh et al. (2004)
showed the usefulness and feasibility of a DNA biochip using a pho-
totransistor integrated circuit. Later there was an effort to reduce the size of the instrument
and increase the number of analytes that could be screened. Anderson et al. (2000) developed
the fiber-optic immunosensor, RAPTOR that permitted the detection of four bacterial agents,
viruses, and toxins.
Rodriguez-Mozaz et al. (2004)
developed the RIANA (based on total
internal reflection fluorescence) biosensor that was able to detect three contaminants
(atrazene, isoprofuron, and estrone) in natural waters.
Schultz et al. (2008)
have developed
a novel array biosensor method that uses the FCFD (fluorescent capillary filler device) on
glass slides, and permits an automated continuous flow assay. DNA hybridization assays
are used.
Figure 16.7a
shows the binding of 500 pM cy3-labelled target (raw data) to a 20-mer capture
probe immobilized on Area 1 on the microarray biosensor (
Schultz et al., 2008
). These
authors showed the vignetting effect, that is the distance of the Area (1, 2, or 3) from
the detector.
Figure 16.7a
shows that a dual-fractal analysis is required to adequately describe
the binding kinetics. The values of (a) the binding rate coefficient,
k
, and the fractal
