Biomedical Engineering Reference
In-Depth Information
(a)
(e)
Ag
Ag-Ag
Au
Au-Au
(b)
Ag
(c)
400
500
600
700
Wavelength (nm)
Au
(f )
s
Au
1.2
Au
s
dsDNA
3 µm
1.0
0.8
ssDNA
(d)
S
iol linker
Au
Au
0.6
DNA
0.4
0.2
Biotin
Spectral
shift
Streptavidin
Streptavidin
0.0
450
500
550
600
650
700
Au or Ag NPs
Pair
Single
Wavelength (nm)
COLOR FIGURE 5.5
DNA-functionalized.gold.and.silver.nanoparticles.(NPs).as.molecular.plasmonic.rulers..(a).First,.streptavidin-
functionalized.nanoparticles.are.attached.to.the.BSA-biotin-coated.glass.surface.(a,.d.left)..Then,.a.second.NP.
is.modiied.by.thiol-ssDNA-biotin.bifunctional.linker.and.attached.to.the.irst.particle.via.biotin-streptavidin.
afinity. binding. (a,. d. right).. Inset:. Principle. of. transmission. dark. ield. microscopy.. (b). Single. silver. particles.
appear.blue.(left).and.particle.pairs.appear.blue-green.(right)..(c).Single.gold.particles.appear.green.(left).and.
gold.particle. pairs.appear.orange.(right).. (e).Representative.scattering.spectra.of.single.particles. and.particle.
pairs.for.silver.(top).and.gold.(bottom)..The.LSPR.scattering.spectrum.for.silver.NPs.shows.a.larger.LSPR.shift.
(102.nm.vs..23.nm),.stronger.light.scattering,.and.a.smaller.half.width.at.half.maximum.(HWHM).than.gold.
particles..(f).Example.of.the.LSPR.spectral.shift.between.a.gold.particle.pair.connected.with.ssDNA.(red).and.
dsDNA.(blue),.corresponding.to.the.distance.increase.of.2.1.nm.between.the.particle.pair.upon.DNA.hybridiza-
tion..(©.2005.Macmillan.Publisher's.Ltd..Used.with.permission.)
