Biomedical Engineering Reference
In-Depth Information
size,.and.ROS.level.of.the.FND-treated.organism.are.not.affected,.indicating.that.FND.is.
an.excellent,.non-toxic.cellular.marker.at.the.whole.animal.level.
25.4 Bioimaging of NDs
25.4.1 Cellular Labeling and Tracking
The.excellent.photostability.and.biocompatibility.of.FND.suggest.that.it.is.well.suited.for.
probing.temporal.and.spatial.events.in.live.cells.by.luorescence.imaging..Particularly.for.
the.(N-V)
−
.center,.its.luorescence.band.peaks.at.∼700.nm.(Figure.25.7),.which.is.well.sepa-
rated.from.the.cell.autoluorescence.derived.from.endogenous.luorophores.such.as.lavin.
(Fu. et. al.. 2007).. Since. the. surface. of. FND. can. be. readily. derivatized. with. various. func-
tional.groups.for.covalent.conjugation.with.bioactive.molecules. for.targeted.bioimaging.
(Krueger.2008,.Mkandawire.et.al..2009,.Weng.et.al..2009),.the.nanoparticle.can.be.applied.
as.a.long-term,.three-dimensional.(3D).tracking.device.in.a.live.cell.
Zhang.et.al..have.illustrated.the.application.of.FND.for.receptor-mediated.targeting.of.
cancer.cells.(Zhang.et.al..2009b)..The.authors.covalently.conjugate.FNDs.with.folic.acid.by.
using.a.biocompatible.polymer,.polyethylene.glycol.(PEG),.as.the.cross-linked.buffer.layer..
Real-time,.3D.tracking.of.single.35.nm.FNDs.during.endocytosis.is.then.performed.with.a.
wide-ield.luorescence.microscope..The.trajectory.of.a.single.FND.inside.a.HeLa.cell.for.a.
time-span.of.more.than.300.s.is.illustrated.in.Figure.25.8..By.analyzing.the.mean.square.dis-
placement.of.the.3D.trajectory.as.shown.in.panel.(c).of.the.igure,.they.ind.that.the.particle.
exhibits.two.distinctly.different.dynamic.behaviors:.(1).conined.diffusion.and.(2).enhanced.
Abs. of flavin
Em. of flavin
Em. of 35 nm FND
Q.E. of CCD
1.0
0.8
0.6
0.4
0.2
0.0
300
400
500 600
Wavelength (mm)
700
800
900
1000
Figure 25.7
(See companion CD for color insert.)
.Comparison.of.emission.spectra.of.lavin.and.FND..Note.that.the.entire.
emission.proile.of.the.35.nm.FNDs.(red).is.well.separated.from.that.of.lavin.(orange).and.also.coincides.with.
the. high. quantum. eficiency. region. (gray). of. the. commonly. used. back-illuminated. CCD. camera.. (Reprinted.
by.permission.from.Fu,.C.-C.,.Lee,.H.-Y.,.Chen,.K.,.Lim,.T.-S.,.Wu,.H.-Y.,.Lin,.P.-K.,.Wei,.P.-K.,.Tsao,.P.-H.,.Chang,.
H.-C.,.and.Fann,.W.,.Characterization.and.application.of.single.luorescent.nanodiamonds.as.cellular.biomark-
ers,.
Proc. Natl. Acad. Sci. USA
,.104,.727-732,.2007..Copyright.2007,.National.Academy.of.Sciences,.USA.)
