Biomedical Engineering Reference
In-Depth Information
FIGURE 3.10
Detection.of.nucleic.acid.targets.using.FRET-based.probes..A.hairpin.probe.with.AuNP.(energy.acceptor).and.
luorescent.dye.(energy.donor).attached.is.added.to.a.solution.containing.denatured.DNA.strands..If.DNA.is.
complementary,. hybridization. occurs,. which. opens. the. hairpin. structure,. separates. the. dye. from. the. AuNP.
quencher,.and.a.luorescent.signal.is.detected..If.DNA.is.noncomplementary,.no.hybridization.occurs.and.no.
luorescent.signal.is.emitted.by.the.dye.due.to.quenching.by.the.AuNP.
antibodies. caused. the. solution. color. to. change. from. red. to. purple. within. 30. min.. The.
LOD.was.1.μg/ml,.with.comparable.sensitivity.to.enzyme-linked.immunosorbent.assays.
(ELISAs),.but.with.the.added.advantage.of.being.a.simple.one-step.test,.as.opposed.to.the.
multiple.steps.required.in.ELISA.
Tang.and.Hewlett
142
.developed.a.BCA.using.AuNPs.to.detect.human.immunodeiciency.
virus.type.1.(HIV-1).p24.antigen..The.detection.sensitivity.using.this.method.was.superior.
to.that.of.ELISA,.where.the.LOD.(0.1.pg/ml).was.100-.to.150-fold.that.of.ELISA.(10-15.pg/
ml)..Moreover,.the.AuNP-based.BCA.was.able.to.detect.the.HIV-1.p24.antigen.in.patients.
with.serconversion.3.days.earlier.than.ELISA.could.
Yang.et.al.
143
.developed.a.chemiluminescent.immunoassay.using.AuNPs.for.the.detec-
tion.of.serum.carcinoembryonic.antigen.(CEA)..AuNPs.were.labeled.with.luminol.and.sec-
ondary.antibodies,.forming.antibody-luminol-AuNP.conjugates..Magnetic.beads.labeled.
with.primary.antibodies.captured.the.serum.CEA,.which.was.then.sandwiched.by.the.sec-
ondary.antibodies.attached.to.the.luminol-AuNPs..The.chemiluminescent.intensity.was.
proportional.to.CEA.concentrations.
Chen.et.al.
144
.developed.an.immuno-PCR.assay.using.functionalized.AuNPs.to.detect.
Hantaan.virus.nucleocapsid.protein.(HNP)..AuNPs.were.functionalized.with.monoclonal.
antibody. L13. speciic. to. HNP. antigen.. The. same. AuNPs. were. conjugated. to. oligonucle-
otides.composed.of.two.strands:.one.directly.attached.to.the.AuNP.and.acting.as.the.cap-
ture.strand,.and.the.other.attached.to.the.capture.strand.by.being.partially.complementary,.
and.acting.as.the.signal.ampliication.DNA..An.ELISA.microplate.was.coated.with.a.poly-
clonal. antibody. used. to. capture. the. HNP. antigen.. Upon. addition. of. the. functionalized.
