Biomedical Engineering Reference
In-Depth Information
+
+
30 μm
θ
(a)
-
-
(b)
20 s
10 μm
t
= 0 s
5 s
60 s
(c)
Figure 19.8
(See companion CD for color igure.)
. Applications. of. optical. tweezers. in. electroporation. mechanism. study..
(a).The.schematics.of.the.positions.of.two.electrodes.and.the.polarization.angle.of.the.optically.trapped.single.
cell.to.the.applied.electric.ield..(b).Visualization.of.the.electric.ield.lines.surrounding.the.trapped.K562.cell.
through. the. tracks. of. negatively. charged. latex. particles.. (c). The. directional. uptake. dynamics. of. propidium.
iodide.(PI).dye.by.a.K562.cell.after.electroporation..(Reproduced.with.permission.from.Henslee,.B.E.,.Morss,.A.,.
Hu,.X.,.Lafyatis,.G.P.,.and.Lee,.L.J.,.Electroporation.dependence.on.cell.size:.Optical.tweezers.study,.
Anal. Chem
.,.
83,.3998-4003,.Copyright.2011,.American.Chemical.Society.).The.snapshots.from.left.to.right.represent.in.order.
for.
t
.=.0.s,.5.s,.20.s,.60.s.post-electroporation.
tweezers.. In. fact,. this. technology. has. been. successfully. used. to. distinguish. living. cells.
from.dead.cells,.and.normal.cells.from.transformed.cells.or.cancer.cells.(Chan.et.al..2006;.
Zheng.et.al..2007)..Similarly,.cells.could.also.be.separated.based.on.their.differences.on.size,.
shape,.refractive.index,.or.morphology..Several.successful.optical.sorting.examples.were.
reported.to.separate.erythrocytes.(biconcave.shape).from.lymphocytes.(spherical.shape).by.
their.obvious.shape.difference.(MacDonald.et.al..2003,.2004;.Ladavac.et.al..2004;.Milne.et.al..
2007;.Smith.et.al..2007)..The.sorting.can.be.done.in.both.luid.low.and.low-free.situations..
In.low-free.cell.sorting,.a.Bessel.beam.or.multiple.beams.are.usually.employed.to.generate.
the. maximum. or. minimum. zones. of. light. intensity.. Cells. are. relocated. in. either. high. or.
low. intensity. zones,. depending. on. their. size,. shape,. or. dielectric. property. differences.
(Paterson.2005;.Richardez-Vargas.et.al..2006)..In.luid.low.optical.sorting,.a.T-.or.Y-shape.
microluidic.channel.is.often.used.to.transport.cell.suspensions.in.which.optical.tweezers.
are.used.to.delect.target.cells.to.the.collection.channel/well.while.the.rest.go.to.the.waste.
channel/well,.as.shown.in.Figure.19.9..Another.type.of.optical.cell.sorting.approach.is.a.
derivate.of.ield.fractionation.or.so-called.optical.chromatography.(Imasaka.et.al..1995)..In.
“optical.chromatography,”.cells.low.through.a.microluidic.channel.while.a.focused.laser.
beam. is. installed. in. the. counter-propagating. direction. of. the. low.. The. scattering. forces.
push.cells.toward.the.low.center.and.the.net.force.on.cells,.when.combed.with.the.drag.
forces,.determines.the.various.equilibrium.positions.for.different.cells.for.further.sorting.
