Biomedical Engineering Reference
In-Depth Information
A
B
2 µm
2 µm
FIGURE 13.5
SEM.images.of.gold.nanowrinkles.on.shrunk.polystyrene.sheets..(A).Biaxial.wrinkles,.inset:.2D.FFT.patterns..
(B).Uniaxial.wrinkles,.inset:.2D.FFT.patterns.
13.3 ImmunoassayDevelopmentUsingNanowrinkles
In.recent.years,.there.has.been.a.growing.interest.in.metal-enhanced.luorescence.(MEF).
technology.as.an.emerging.tool.in.the.ield.of.immunoassay.development..The.effect.and.
mechanisms. of. MEF. have. been. discussed. extensively. elsewhere.
40-67
. Briely,. MEF. is. the.
method. of. using. metal. structures. or. particles. in. close. proximity. to. the. luorophore. to.
increase.the.brightness.and.photostability.of.the.luorophore..Depending.on.the.distance.
between.the.luorophore.and.metal.surfaces.or.particles,.the.luorescence.can.be.quenched.
or.enhanced.several.thousand-fold..The.luorescence.signal.enhancement.can.be.explained.
by.at.least.two.mechanisms..First,.the.metal.surfaces.and.colloids.are.able.to.amplify.the.
incident. ield. by. concentrating. the. local. excitation. intensity.. Second,. the. close. proxim-
ity. of. metal. and. luorophores. can. increase. the. radiative. decay. rate. of. the. luorophores..
1.2
10 nm
50 nm
Biaxial
0.9
0.6
0.3
0.0
0.1
1
10
Wrinkles Wavelength (µm)
FIGURE 13.6
Wavelength.distributions.of.biaxial.wrinkles.for.varying.gold.thicknesses.(10-50.nm).
