Biomedical Engineering Reference
In-Depth Information
1.2
30nm
40nm
50nm
60nm
70nm
80nm
90nm
100nm
1.0
0.8
0.6
0.4
0.2
0.0
400
500
600
λ
max
(nm)
700
800
Figure 4.9
UV-Vis spectra for Au nanoparticles with dif erent particle sizes in aqueous
solution [45].
400 nm
Light color
750 nm
Silver rods
Silver spheres
Gold rods
Gold spheres
Gold shells with hollow interiors
Gold/silver alloyed spheres
Silver plates
Silver cubes
Figure 4.10
Position of SPR band can be tuned using gold and silver nanoparticles of
various structures and morphologies [44].
100 nm. In contrast SPR band can be tuned in the region from visible to
near-infrared by varying the shape and size of the nanoparticles [45, 46].
It has been shown that when a transition in shape from sphere to rods
is made, a single broad plasmon absorption band splits into two plasmon
bands. Peak at shorter wavelength due to transverse plasmon resonance
while peak at higher wavelength due to longitudinal plasmon resonance.
h e wavelength of longitudinal plasmon band is tunable from visible to
near-infrared by changing the aspect ratio [47]
h ere are many dif erent ways to synthesize gold NPs:
•
Citrate Reduction Method
[45, 46] is i rst reported by
Turkevich and is popularly used to generate spherical gold
