Biomedical Engineering Reference
In-Depth Information
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Figure 1.26
Detection via alteration of incident angle and production of SPR
sensorgram.
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Figure 1.27
Simplified schematic of SPR imaging experiment.
laterally structured coatings on thin metal films could be examined using
imaging technology. The sample is illuminated with an expended beam of
parallel light over relatively large areas. With the angle of incidence and
wavelength kept constant, the detection mode is the measurement of reflected
light by a charge-coupled device (CCD) camera. A schematic of this sort of
experiment is depicted in Figure 1.27. Since the 1980s there has been a
proliferation of array-based SPR detection systems largely spawned by the
concomitant rapidly developing interest in protein and nucleic acid microarray
analysis in the early 2000s. These days equipment is available for the assay of
thousands of domains imposed on a substrate, much as is evident with the more
conventional confocal fluorescence microscopy technology. Further devel-
opments in SPR detection have been connected with improvement of chip
design, use of interferometry, replacement of gold as the plasmon substrate and
use of nanowire technology to observe plasmon processes.
Finally with regard to SPR, we briefly outline for the reader a comparison of
the technique with acoustic wave (AW) physics, described above, since these
methods are used for very similar purposes.
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SPR is clearly far more advanced than AW in terms of instrument
development especially when it comes to sample introduction and
imaging, etc.
Flow-through detection: Both techniques are conventionally employed in
the real-time flow injection mode.
Label-free: Both techniques offer the highly significant advantage in
bioanalytical chemistry of being capable of operation in a label-free
