22
The validity of the NRL Array Biosensor was demonstrated for the detection of
mycotoxins (ochratoxin A, deoxynivalenol, and aflatoxin B1) in various food
matrices and air [32–35].
This competitive assay protocol involved attaching the biotinylated mycotoxin
derivatives onto the waveguide, this was followed by incubating the test sample
with cyanine 5 (Cy5)-labeled anti-toxin antibodies and then passing the preincubated mix over the immobilized mycotoxin derivatives. Since the immobilized
mycotoxin derivatives competed with the toxin in the test sample for binding to the
fluorescent antibodies; it was found that the resulting fluorescent signal of the
immunocomplex on the waveguide surface was inversely proportional to the
concentration of toxin in the sample (decrease in signal with increasing concentration
[32–35].
This type of Array Biosensor has been automated and miniaturized for operation
as point-of-use quantitative immunoassay arrays. This methodology was utilized to
measure an expanded number of toxins and toxin indicators in food and clinical
fluids. In addition, semi-selective recognition molecules were also used to expand
the repertoire of toxins that can be detected on a single array. In the automated
system, up to 6 samples can be analyzed simultaneously while the non-automated
system can test up to 12 samples [30].
2.3.2.2 Use of Antimicrobial Peptides for Toxin Detection
Taitt and coworkers investigated the possibility of using antimicrobial peptides
(AMPs) for the detection of inactivated botulinum toxins A, B, and E as well as
other toxins in assays analogous to the AMP-based bacterial assays [36]. They
observed apparent differences in the patterns of binding between botulinum
neurotoxoids A, B, and E. It was found that the detection limits were improved
when immobilized AMPs were used for target capture [36].
2.3.3 Surface Acoustic Wave (SAW) Sensors
The Love wave (LW) physical effect was firstly revealed by the mathematician
Augustus Edward Hough Love [37, 38]. Typically, LW sensors consist of two
components, which are the transducing area and the sensing area. The transducing
area consists of the interdigital transducers (IDTs), which are metal electrodes,
sandwiched between the piezoelectric substrate and the guiding layer [39–41]. The
input IDT is excited through the application of an rf signal and introduces a
mechanical acoustic wave into the piezoelectric substrate, which is directed across
the guiding layer up to the output IDT, then it is converted back to a measurable
electrical signal (Fig. 2.8) [40].
It should be understood that the sensing area is the part of the sensor surface,
positioned between the input and output IDT, which is exposed to the analyte.
J. H. Banoub and A. Mikhael
The validity of the NRL Array Biosensor was demonstrated for the detection of
mycotoxins (ochratoxin A, deoxynivalenol, and aflatoxin B1) in various food
matrices and air [32–35].
This competitive assay protocol involved attaching the biotinylated mycotoxin
derivatives onto the waveguide, this was followed by incubating the test sample
with cyanine 5 (Cy5)-labeled anti-toxin antibodies and then passing the preincubated mix over the immobilized mycotoxin derivatives. Since the immobilized
mycotoxin derivatives competed with the toxin in the test sample for binding to the
fluorescent antibodies; it was found that the resulting fluorescent signal of the
immunocomplex on the waveguide surface was inversely proportional to the
concentration of toxin in the sample (decrease in signal with increasing concentration
[32–35].
This type of Array Biosensor has been automated and miniaturized for operation
as point-of-use quantitative immunoassay arrays. This methodology was utilized to
measure an expanded number of toxins and toxin indicators in food and clinical
fluids. In addition, semi-selective recognition molecules were also used to expand
the repertoire of toxins that can be detected on a single array. In the automated
system, up to 6 samples can be analyzed simultaneously while the non-automated
system can test up to 12 samples [30].
2.3.2.2 Use of Antimicrobial Peptides for Toxin Detection
Taitt and coworkers investigated the possibility of using antimicrobial peptides
(AMPs) for the detection of inactivated botulinum toxins A, B, and E as well as
other toxins in assays analogous to the AMP-based bacterial assays [36]. They
observed apparent differences in the patterns of binding between botulinum
neurotoxoids A, B, and E. It was found that the detection limits were improved
when immobilized AMPs were used for target capture [36].
2.3.3 Surface Acoustic Wave (SAW) Sensors
The Love wave (LW) physical effect was firstly revealed by the mathematician
Augustus Edward Hough Love [37, 38]. Typically, LW sensors consist of two
components, which are the transducing area and the sensing area. The transducing
area consists of the interdigital transducers (IDTs), which are metal electrodes,
sandwiched between the piezoelectric substrate and the guiding layer [39–41]. The
input IDT is excited through the application of an rf signal and introduces a
mechanical acoustic wave into the piezoelectric substrate, which is directed across
the guiding layer up to the output IDT, then it is converted back to a measurable
electrical signal (Fig. 2.8) [40].
It should be understood that the sensing area is the part of the sensor surface,
positioned between the input and output IDT, which is exposed to the analyte.
J. H. Banoub and A. Mikhael