Biomedical Engineering Reference
In-Depth Information
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Figure 25.8
(See companion CD for color insert.)
. Three-dimensional. tracking. of. single. folate-conjugated. FNDs. during.
endocytosis. by. a. live. HeLa. cell.. (a). Bright-ield. image. of. the. HeLa. cell. after. internalization. of. 35.nm. FND-
PEG-FA.particles..(b).Three-dimensional.trajectory.(shown.in.pseudocolor).of.a.single.FND-PEG-FA.particle,.
marked. by. the. red. square. in. (a),. over. a. time. period. of. 370.s.. (c). Variation. of. the. mean. square. displacement.
(MSD). of. the. tracked. FND-PEG-FA. particle. with. time.. Regimes. I. and. II. correspond. to. conined. diffusion.
and. enhanced. diffusion. of. the. particle,. respectively.. (From. Zhang,. B.,. Li,. Y.,. Fang,. C.-Y.,. Chang,. C.-C.,. Chen,.
C.-S.,.Chen,.Y.-Y.,.and.Chang,.H.-C.:.Receptor-mediated.cellular.uptake.of.folate-conjugated.luorescent.nano-
diamonds:.A.combined.ensemble.and.single-particle.study..
Small
..2009b..5..2716-2721..Copyright.Wiley-VCH.
Verlag.GmbH.&.Co..KGaA,.Reprinted.with.permission.)
diffusion..In.the.irst.regime,.the.particle's.movement.is.restricted,.which.can.be.associated.
with.particle.engulfment..In.the.second.regime,.the.particle's.enhanced.movement.is.inter-
preted.as.a.result.of.the.directed.motion.with.the.engulfed.particle.pinched.off.from.the.cell.
membrane.and.enclosed.within.an.endosome,.which.is.then.actively.transported.to.the.cell.
interior.along.a.network.of.tubulovesicular.structures.
Faklaris.et.al..(2009).have.also.studied.the.internalization.and.diffusion.of.acid-treated.
FNDs.in.HeLa.cells.with.a.2D.dynamic.tracking.technique..The.diffusion.coeficient.of.the.
acid-treated.particles.in.HeLa.cells.is.determined.to.be.smaller.than.0.01.μm
2
/s..Similarly,.
Neugart.et.al..have.investigated.the.diffusion.of.FNDs.in.HeLa.cells.and.found.that.FND.
particles.coated.with.sodium.dodecyl.sulfate,.as.a.surfactant,.are.internalized.into.the.cells.
after.3.h.of.incubation.(Neugart.et.al..2007)..Most.of.the.FNDs.are.immobilized.inside.the.
cells.after.a.short.time.with.few.freely.diffusing.single.particles..More.recently,.Hui.et.al..
have.reported.that.the.encapsulation.of.FND.within.a.lipid.layer.enhances.the.dynamics.
of. the. particle. in. the. cytoplasm. by. more. than. one. order. of. magnitude,. which. is. further.
conirmed. by. luorescence. correlation. spectroscopy. (Hui. et. al.. 2010b).. The. potential.
