Biomedical Engineering Reference
In-Depth Information
that the primary antibody conjugated gold nanoparticles and the nonconjugated primary anti-
body solution mixture were immobilized on the test line of the immunochromatographic test
strip. Following the immobilization procedure, the antigen and the gold nanoparticle-
conjugated secondary antibody were introduced onto the conventional and sensitive immuno-
chromatographic test strips. The authors explain that the nanoparticle-conjugated primary
antibodies and the nanoparticle-conjugated secondary antibodies accumulate because of
immunogenic reactions.
Sonnichsen et al. (2005)
point out that the LSPR (localized surface
plasmon reaction) absorbance of the gold nanoparticles depends on the distance between the
gold nanoparticles. Since the antigen-antibody reaction brings a high amount of gold
nanoparticles together,
Nagatani et al. (2006)
report that a distinct red color may be seen with
the naked eye.
Nagatani et al. (2006)
report that by using their sensitive immunochromatographic test strip
for the detection of PSA
(a)
they were able to decrease the amount of antibody used by 50% for the same sensitivity.
This facilitates a lower cost,
(b)
their method provided a higher sensitivity in the test line when compared with the con-
ventional method used now,
(c)
their method could use the naked eye to screen PSA concentrations with a color sample
sheet for first screening.
They conclude that their sensitive method exhibits the potential for entering the commercial
market as a diagnostic device to detect PSA in the near future.
5.6 In Vitro Characterization of an Intracellular Nanosensor
for ROS (
Henderson et al., 2009
)
Henderson et al. (2009)
have recently developed an intracellular nanosensor for real-time
monitoring of ROS. Their nanosensor is based on PEBBLE (probes encapsulated by biologi-
cally localized embedding) technology. The authors used a sensitive ROS probe
dihydrorhodamine 123 (DHR 123) as the sensing element of the PEBBLE device. This
was done by entrapment within a porous, bio-inert polyacrylamide nanostructure. According
to the authors, this permitted a passive monitoring of the free radical species. They believe
that though previous analyses have used fluorescent probes to analyze ROS, they have been
found to be cytotoxic and can influence cellular metabolism and adversely affect
in vitro
data. The authors explain that they were able to stimulate the PEBBLE loaded NR8383 cells
with PMA (phorbol-12-myristate-13-acetate), which permitted them to carry out real-time
monitoring of ROS without affecting cellular viability. They report that their PEBBLE
technology provides distinct advantages over existing technologies for monitoring the
intracellular environment.
