Biomedical Engineering Reference
In-Depth Information
(a)
a
b
c
4 µm
10 µm
10 µm
Effective Shell ‰ickness (nm)
(b)
0
5
10
15
20
1.2
Au-ph-DNA
Au-ph-DNA
2.2
0
5
10
15
20
2
30
35
40
45
50
55
60
65
+
Kpn
I
1.0
+
Sal
I
+
Kpn
I
2.1
+
Xho
I
+
Hind
III
0.8
2.0
Au-ph
+
Sal
I
1.9
0.6
+
Xho
I
1.8
0.4
+
Hind
III
1.7
0.2
Au-ph
1.6
0.0
500
550
600
650
700
0
10
20
30
40
50
60
Wavelength (nm)
Base Pairs Remaining on Ruler
FIGURE 5.6
(See. color. insert.). Nanoplasmonic. molecular. rulers. for. measuring. nuclease. activity.. (a). Dark. ield. scattering.
images:.a,.single-target.single.nanoparticle.isolated.from.other.Au.or.Au-DNA.NPs.for.spectroscopic.examina-
tion;.b,.c,.true-color.images.of.single.Au.NP.(b).(540.nm.peak).and.Au-DNA.NP.(c).(607.nm.peak)..(b).Typical.
LSPR.scattering.spectra.and.the.corresponding.maximum.scattering.wavelengths.(
λ
max
).of.the.Au-DNA.nano-
conjugates.after.cleavage.reactions.with.four.endonucleases.(
Hind
III,.
Xho
I,.
Sal
I,.and.
Kpn
I).and.as.a.function.of.
the.number.of.base.pairs.remaining.attached.to.the.Au.nanoparticle.after.the.cleavage..The.red.curve.is.a.it.from.
a.semiempirical.model.using.a.Langevin-type.dependence.of.the.refractive.index.vs..dsDNA.length..The.error.
bars.represent.the.standard.deviation.in.the.measurement.of.20.nanoparticles..(©.2006.Macmillan.Publisher's.
Ltd..Used.with.permission.)
to.1..seml
−u
..This.biochip.can.potentially.it.a.variety.of.applications,.such.as.point-of-care.
of.care.devices,.cancer.diagnosis,.and.microorganism.detection.for.biodefense.
5.5.3 Case 3: Coupling LSPR with SERS
For.a.particular.Raman.band,.Van.Duyne.and.his.team.found.that.the.optimal.condition.is.
achieved.when.the.LSPR.λ
max
.equals.the.excitation.wavelength.(in.absolute.wavenumbers).
minus.one-half.the.Stokes.shift.of.the.Raman.scattering.band.
95
.Furthermore,.the.LSPR.can.
be.easily.tuned.by.changing.the.size.and.shape.of.NPs..Therefore,.LSPR.nanobiosensors.
become.ideal.candidates.for.a.complementary.molecular.identiication.platform.to.SERS
8b
.
so. that. a. Raman. ingerprint. could. be. used. to. identify. unknown. molecules. that. cannot.
be.achieved.by.biological.recognition.elements.of.LSPR.nanobiosensors..The.team.dem-
onstrated. the. complementary. nature. of. LSPR. spectral. shift. assays. and. SERS. molecular.
identiication.with.the.antidinitrophenyl.immunoassay.system.
96
.Binding.of.the.antidini-
trophenyl.ligand.to.2,4-dinitrobenzoic.acid.was.quantiied.by.measuring.LSPR.shift,.while.
SERS.was.used.to.verify.the.identity.of.the.adsorbed.molecules.
