Biomedical Engineering Reference
In-Depth Information
function of the bulk refractive index around the nanoparticles has
been reported for nanorods,
26
hollow nanoshells,
27
nanorings,
28
nanodisk,
29
nanocubes,
30
triangular nanoprisms,
31
nanodecahedra,
32
nanobipyramids,
33
crescent-shaped nanoparticles,
34
d
nanobranches,
35
and those nanostructures provide a chance to be
used in biosensor development. Using electrodynamic simulations of
gold nanoparticle spectra, Miller and Lazarides demonstrate that the
sensitivity of a plasmon peak wavelength to a variation in RI of the
environment is determined by the location of the peak wavelength
and the dielectric properties of the material.
36
Later, Wang and
coworkers
35
have carried out a systematic study on the sensitivity
of AuNPs of various shapes, including nanospheres, nanocubes,
nanobranches, nanorods, and nanobipyramids toward bulk RI
changes by using both RISs and igures of merits as performance
indicators. They have found that the sensitivities generally increased
as AuNPs became elongated and their apexes became sharper.
Figure 4.5
(A) Scanning electron microscopy of ilms of gold nanorods. (B)
Schematic of the nanorod-based immunoassay. The nanorods
were ixed to a glass surface via an APTES monolayer, and
then coated with a self-assembled monolayer to which the
capture antibody is coupled by carbodiimide cross-linking.
The substrate was exposed to antigen (in this case secondary
antibodies) and the binding was monitored via real-time
absorption spectra. Reprinted with permission from ref. 39,
Copyright 2008, American Chemical Society.
Although gold nanospheres are popular since they can be easily
prepared, gold nanorods display a much higher sensitivity toward
bulk refractive index changes than AuNPs (366 nm/RIU for
Au nanorods with a mean aspect ratio of 5.2 and 76.4 nm/RIU
for AuNPs).
37
Such a biosensing material was further modiied
to demonstrate its effectiveness in quantitative detection for
Search WWH ::
Custom Search