Biomedical Engineering Reference
In-Depth Information
I
II
III
IV
V
Size of DNA
Figure 18.2
DNA.separation.regimes.in.gel.or.entangled.polymer.matrix:.DNA.mobility.vs..size..(Reproduced.with.per-
mission. from. Springer. Science+Business. Media:.
Nanoscience-Nanobiotechnology and Nanobiology
,. Electrical.
characterization. and. dynamics. of. transport,. 639-742,. Picollet-D'Hahan,. N.,. Amatore,. C.,. Arbault,. S.. et. al.,.
Copyright.2010.)
of.DNA,.RNA,.protein,.and.even.nanoparticles..Both.gel.and.capillary.EP.are.matured.
techniques.and.have.been.widely.used..However,.they.have.their.intrinsic.limitations..For.
example,.there.is.a.size.threshold.for.separation,.i.e.,.long.DNA.molecules.or.fragments.
(>100.kbps).cannot.be.eficiently.separated..Also,.both.techniques,.especially.the.gel.EP,.
are. slow. in. process.. In. order. to. improve. the. eficiency. and. increase. the. throughput. of.
DNA.separation,.people.turn.their.attentions.to.nanoluidics.since.it.has.the.potential.to.
separate.DNAs.in.all.sizes..In.this.section,.we.only.list.some.important.nanoluidics-based.
techniques.that.greatly.improve.our.understandings.on.mechanisms.of.DNA.separation.
As.clearly.shown.in.Figure.18.2,.DNA.separation.in.gel.or.entangled.polymer.matrices.
can.have.ive.different.regimes.or.mechanisms,.depending.on.the.size.of.DNAs:.(I).free.
migration,.(II).Ogston.iltration,.(III).separation.by.repetition,.(IV).separation.by.collision,.
and.(V).migration.with.orientation.(Picollet-D'Hahan.et.al..2010).
Artiicial. micropillar. arrays. mimic. the. separation. mechanisms. (II). and. (III). of. gel. or.
capillary.EP.and.have.demonstrated.the.ability.to.separate.long.DNA.molecules.of.around.
50-100.kbps.. The. miniaturization. to. nanoscale. has. been. reported. and. the. separation.
mechanism. (IV)—collisions. between. DNAs. and. nanopillars—can. be. directly. observed.
(Kaji.et.al..2004)..Figure.18.3a.shows.the.schematics.of.artiicial.EP.using.nanopillar.arrays..
In.Figure.18.3b,.collisions.of.long.DNA.molecules.such.as.λ-DNA.(48.kbps).and.T4-DNA.
(166.kbps). with. nanopillar. arrays. are. compared.. Collisions. of. T4-DNA. with. nanopillars.
are.more.frequent.than.with.λ-DNAs.since.T4-DNA.is.longer.with.more.chances.to.form.
the. U-shaped. structure.. Thus,. T4-DNAs. have. a. lower. effective. EP. mobility. and. can. be.
separated. from. λ-DNAs.. Several. key. factors. such. as. the. size. of. the. nanopillar,. density.
or.spacing.between.neighboring.nanopillars,.and.patterns.of.nanopillar.array.have.been.
