Biomedical Engineering Reference
In-Depth Information
is.nonspeciic.and.causes.damage.to.normal.as.well.as.cancer.cells.
115
.Moreover,.recurrence.
after.RFA.has.been.reported.to.occur.at.high.rates.
116,117
.Cardinal.et.al.
115
.used.AuNPs.exposed.
to.an.RF.ield.to.thermally.ablate.liver.cancer.cells.both.in.vitro.and.in.vivo..To.study.the.
effect.in.vitro,.HepG2.liver.cancer.cells.were.cultured.in.the.presence.of.AuNPs.synthesized.
by.the.citrate.reduction.method..About.80%.of.the.cells.cultured.in.vitro.had.been.success-
fully.ablated.after.exposure.to.35.W.RF.power.for.7.min..To.study.the.effect.in.vivo,.JM-1.
cells.were.injected.into.rats.and.allowed.14.days.to.form.subcutaneous.tumors..The.AuNPs.
were.then.directly.injected.into.the.subcutaneous.tumors.and.exposed.to.RF.power.of.35.W..
Histopathologic.assessment.of.the.subcutaneous.tumors.after.RFA.using.AuNPs.also.showed.
signs.of.widespread.thermal.injury.and.apoptosis..In.both.models,.the.hyperthermia.gener-
ated.by.the.AuNPs.depended.on.the.exposure.time.and.power.of.RF.current.
3.5.1.2.2 Bacteria
Photothermal.technology.has.also.been.used.in.targeting.and.killing.bacterial.cells..Zharov.
et.al.
118,119
.used.PTT.and.AuNPs.to.target.
Staphylococcus aureus
.bacteria..Gold.nanospheres.
of.diameters.10-40.nm.were.conjugated.with.anti-protein.A.monoclonal.antibodies,.tar-
geting.protein.A,.which.is.attached.to.the.cell.wall.of.Staph.isolate.UAMS-1..Upon.laser.
radiation,.only.bacteria.labeled.with.40.nm.AuNPs.were.killed.after.500.pulses.at.532.nm.
laser.wavelength..Higher.killing.eficiency.was.observed.when.the.nanospheres.clustered.
due.to.aggregation.
3.5.1.2.3 Wound Closure
Lasers.have.been.used.in.the.closure.of.wounds.as.an.alternative.to.suturing.
120
.In.laser.
soldering,.exogenous.chromophores.are.mixed.with.proteins.or.polymers,.and.the.paste.
is.inserted.between.the.wound's.margins..Upon.NIR.radiation,.the.chromophores.convert.
the.radiation.to.heat,.and.these.proteins.or.polymers.coagulate,.acting.as.clots.and.closing.
the.wound.
120
.These.clots.are.then.naturally.resorbed.by.the.tissue..Gobin.et.al.
121
.applied.
this. method. to. seal. muscular. and. cutaneous. tears. by. replacing. the. chromophores. with.
gold.nanoshells.in.an.albumin.iller.
In.laser.welding,.chromophores,.such.as.indocyanine.green.(ICG),
122
.are.applied.to.the.
wound's.margins
123
.and.convert.NIR.radiation.to.heat,.which.leads.to.reorganization.of.the.
tissue. by. diffusion,
124
. leading. to. minimal. scar. formation.. Such. chromophores,. however,.
are.highly.diffusive.and.have.limited.eficiency.and.stability,.as.opposed.to.AuNPs.
28
Ratto. et. al.
28
. used. gold. nanorods. as. NIR. chromophores. for. the. welding. of. connective.
tissue.of.the.porcine.eye.lens.capsule..The.gold.nanorods.were.synthesized.using.the.seed-
mediated.method
42
.to.have.an.aspect.ratio.of.approximately.4,.and.placed.in.a.sandwich.
manner.between.the.internal.side.of.the.donor.capsule.and.the.external.side.of.the.recipi-
ent.capsule,.so.that.adhesion.of.the.capsules.can.occur.while.preserving.their.curvature..
The.contact.welding.technique.was.used.with.an.810.nm.diode.laser.and.40.ms.duration.
of.pulses..Collagen.denaturation.and.fusion.of.patches.were.achieved,.indicating.a.rise.in.
temperature.beyond.50°C.(the.temperature.at.which.collagen.denaturation.occurs).
3.5.2 Diagnostics
AuNPs.have.gained.popularity.in.the.diagnostics.arena,.due.to.their.unique.optical.and.
physical. properties. and. their. tunability. by. variation. of. shape,. size,. and. compositions,.
thus.enabling.their.use.in.the.detection.of.multiple.targets.simultaneously.
2
.AuNPs.can.be.
applied.in.immuno.and.molecular.assays.using.a.wide.range.of.detection.techniques,.such.
as. colorimetric,. luorescent. based,. scanometric,. and. electrochemical.. Assays. involving.
