Biomedical Engineering Reference
In-Depth Information
In an attempt to study the sensitivity of a TW-PPR sensor, an
integration of a simple optical setup and a glass tube (inner diameter
= 4.2 mm, outer diameter = 5.0 mm, length = 31 mm) with one closed
end as shown in Fig. 5.7 were used. GNPs were immobilized on the
inner wall of the glass tube. When I S / I R is plotted versus RI of the
surrounding medium, a linear it ( R = 0.9971) is observed. From the
plot, a RIR of 5.4 × 10 −6 RIU and a slope of 8.6 AU/RIU is estimated.
Such a high sensitivity is probably due to the long sensor length and
the large surface area available for immobilization of NMNPs and
their interactions with the sample. It has been demonstrated that
a long optical path TW absorbance sensor can be achieved by using
a lexible fused-silica capillary. 88 Unfortunately, theoretical models
for TW absorbance sensors have not been found in literatures, but
models based on iber optic absorbance sensors should be useful for
TW absorbance sensors.
As shown in Fig. 5.8A, upon serial injection of streptavidin
samples of increasing concentration, biomolecular interaction of
streptavidin with biotin on the GNP surface can be observed in real-
time. When I S / I R is plotted versus log streptavidin concentration as
shown in Fig. 5.8B, a linear it ( R = 0.9964) is observed. From this
calibration graph, a DL of 3.3 × 10 −12 M for streptavidin is estimated.
Because of the small size and self-contained sample holding design,
the TW-PPR biosensor has a high potential of being developed to be
a portable biosensor. Furthermore, when the tubular waveguides
are arranged in an array, a high throughput biosensing system is
anticipated.
Figure 5.8 (A) Temporal responses of a biotin-functionalized TW-
PRR sensor with serial injection of streptavidin samples of
increasing concentration. (B) Calibration graph of I S / I R versus
log streptavidin concentration.
 
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