Biomedical Engineering Reference
In-Depth Information
biomolecules in the SPB patches is 16 times higher than on a bare
gold surface.
(D)
(A)
(B)
(C)
Figure 4.8
(A) Representative SEM image of
D
~ 60 nm holes in a gold
ilm (
h
= 20 nm) at a density of ~60 holes/μm
2
. Dark-ield
microscopy images of (B) dense and (C) isolated nanoholes,
respectively. (D) Schematics of the experimental setup.
Reprinted with permission from ref. 55, Copyright 2005,
American Chemical Society.
Due to the laterally propagating nature of the surface plasmon
polaritions, the lateral resolution of the PSPR sensors is limited
to tens of micrometers. On the contrary, LSPR nano-sensor arrays
will provide pixel sizes 20-50 times smaller than the PSPR sensor
arrays.
56
In principle, the smallest possible pixel size is the size of
one nanoparticle. Taking this ideal case in mind, single AuNPs
57
and
single Au nanorods
58
were used to detect biotin and a detection
limit of 1 nM was achieved by using Au nanorods,
58
while single Ag
nanoparticles were used to detect thiol adsorption and a zeptomole
sensitivity was achieved.
59
Moreover, the method used to immobilize
the single Au triangular nanoprism on the substrate can strongly
affect the sensitivity toward refractive index changes.
60
The study
shows that the LSPR resonance is not as sensitive to the medium
when the particle is adsorbed to a substrate.
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