33
standalone sensors for the site/building protection, emergency response, rapid
screening, and environmental monitoring [58].
To summarize, the CANARY’s capabilities open possible applications in pathogen genotyping, virulence testing, antibiotic resistance screening, and viability
assessment. Moreover, using these cells demonstrate the best-known combination
of speed and sensitivity. Other applications of CANARY technology comprise biological aerosol sampling, point-of-care diagnostics, pre-symptomatic diagnosis in
the outcome of a biowarfare attack, finding of agricultural pathogens at ports of
entry, or screening of perishable food supplies medium [62], which activates the
aequorin, causing it to emit light [59, 60].
2.3.6 High-Density Microsphere-Based Fiber-Optic
DNA Microarrays
It is well known that an optical fiber is a flexible, translucent fiber produced by
drawing glass (silica) or plastic to a diameter slightly thicker than that of a human
hair [65, 66]. Optical fibers consist of an inner core that is surrounded by a clad
material of a lower refractive index. Because of the differences in refractive index,
light is totally reflected. A fiber optic bundle consists of thousands of individual
fibers fused together, such that each fiber retains its ability to transmit light
independently of its neighbors (Fig. 2.17) [67].
Pantano and Walt showed that by selectively etching the fiber core, an array of
microwells could be formed [68, 69]. These microwells can be filled with
oligonucleotide-functionalized microspheres. The array dimensions can be tailored
to suit any size of the oligonucleotide-functionalized microsphere. The well diameters are equal to those of the fiber cores, and the depths are dependent on the
etchant concentration, the exposure time, and the fiber composition. Because each
microsphere is optically wired to fiber, the specific interactions on each microsphere
surface can be independently monitored. Walt and coworkers developed a highdensity fiber-optic DNA microarray containing oligonucleotide-functionalized, 3.1m-diameter microspheres haphazardly distributed on the etched face of an imaging
fiber bundle [68, 69].
Usually, these fiber bundles are composed of around 6000–50,000 fused optical
fibers, in which each fiber contains an etched well [70]. The desired oligonucleotide
sequences are attached to individual microspheres, then added to each etched wells
on the fiber optic bundle face. The produced microwell arrays are capable of casing
complementary-sized microspheres, each containing thousands of copies of a
unique oligonucleotide probe sequence. Walt and coworkers showed that the array
fabrication process resulted in random microsphere placement. It should be understood that the determination of the position of microspheres in the random array,
essentially required an optical encoding scheme. The detection schemes, which are
combined the intrinsic recognition abilities of nucleic acids, are usually measured
2 Detection of Biological Warfare Agents Using Biosensors
standalone sensors for the site/building protection, emergency response, rapid
screening, and environmental monitoring [58].
To summarize, the CANARY’s capabilities open possible applications in pathogen genotyping, virulence testing, antibiotic resistance screening, and viability
assessment. Moreover, using these cells demonstrate the best-known combination
of speed and sensitivity. Other applications of CANARY technology comprise biological aerosol sampling, point-of-care diagnostics, pre-symptomatic diagnosis in
the outcome of a biowarfare attack, finding of agricultural pathogens at ports of
entry, or screening of perishable food supplies medium [62], which activates the
aequorin, causing it to emit light [59, 60].
2.3.6 High-Density Microsphere-Based Fiber-Optic
DNA Microarrays
It is well known that an optical fiber is a flexible, translucent fiber produced by
drawing glass (silica) or plastic to a diameter slightly thicker than that of a human
hair [65, 66]. Optical fibers consist of an inner core that is surrounded by a clad
material of a lower refractive index. Because of the differences in refractive index,
light is totally reflected. A fiber optic bundle consists of thousands of individual
fibers fused together, such that each fiber retains its ability to transmit light
independently of its neighbors (Fig. 2.17) [67].
Pantano and Walt showed that by selectively etching the fiber core, an array of
microwells could be formed [68, 69]. These microwells can be filled with
oligonucleotide-functionalized microspheres. The array dimensions can be tailored
to suit any size of the oligonucleotide-functionalized microsphere. The well diameters are equal to those of the fiber cores, and the depths are dependent on the
etchant concentration, the exposure time, and the fiber composition. Because each
microsphere is optically wired to fiber, the specific interactions on each microsphere
surface can be independently monitored. Walt and coworkers developed a highdensity fiber-optic DNA microarray containing oligonucleotide-functionalized, 3.1m-diameter microspheres haphazardly distributed on the etched face of an imaging
fiber bundle [68, 69].
Usually, these fiber bundles are composed of around 6000–50,000 fused optical
fibers, in which each fiber contains an etched well [70]. The desired oligonucleotide
sequences are attached to individual microspheres, then added to each etched wells
on the fiber optic bundle face. The produced microwell arrays are capable of casing
complementary-sized microspheres, each containing thousands of copies of a
unique oligonucleotide probe sequence. Walt and coworkers showed that the array
fabrication process resulted in random microsphere placement. It should be understood that the determination of the position of microspheres in the random array,
essentially required an optical encoding scheme. The detection schemes, which are
combined the intrinsic recognition abilities of nucleic acids, are usually measured
2 Detection of Biological Warfare Agents Using Biosensors