Biomedical Engineering Reference
In-Depth Information
For.the.sake.of.bioimaging.applications,.the.FNDs.produced.should.be.small.and.each.
particle.should.contain.as.many.color.centers.as.possible..Morita.et.al..have.separated.ND.
particles.of.smaller.sizes.by.ultracentrifugation,.a.method.commonly.used.for.particle.
size. sorting. (Morita. et. al.. 2008).. The. median. size. of. the. separated. NDs. can. be. tuned.
from. 4. to. 25.nm. by. controlling. the. conditions. of. the. centrifugation.. Several. research.
groups. have. employed. similar. techniques. to. select. smaller. ND. particles. and. then.
convert.them.to.FNDs.by.electron.or.ion.bombardment.(Faklaris.et.al..2008,.Mohan.et.al..
2010b,.Rondin.et.al..2010,.Hui.et.al..2011)..The.smallest.size.of.FND.is.reported.to.be.near.
10.nm..Boudou.et.al.,.on.the.other.hand,.have.taken.a.very.different.approach.to.produce.
FNDs. (Boudou. et. al.. 2009).. Microdiamond. powders. are. irst. irradiated. by. a. proton.
beam.of.2.5.MeV..The.irradiated.particles.are.then.annealed.at.750°C.to.form.luorescent.
microdiamonds.. To. further. convert. luorescent. microdiamonds. into. smaller. particles,.
the.authors.apply.nitrogen.jet.milling.to.decrease.the.particle.size..The.size.of.the.milled.
FNDs.becomes.smaller.than.10.nm.and.these.particles.show.good.photostability.(Tisler.
et. al.. 2009).. Finally,. Rabeau. et. al.. have. made. an. attempt. to. produce. (N-V)
−
. centers. in.
NDs.synthesized.by.CVD.(Rabeau.et.al..2007)..These.NDs.are.grown.directly.on.quartz.
cover.slips.in.a.microwave.plasma.CVD.reactor..Single.(N-V)
−
.centers.are.observable.in.
the.resultant.nanocrystals.
25.3 Biocompatibility of ND
Recent.advances.in.nanotechnology.have.led.to.widespread.applications.of.nanoparticles.
in.life.sciences..With.the.rapid.development.of.the.ield,.there.have.been.serious.disputes.
about. the. safety. evaluation. of. nanomaterials. (Kuzma. 2007).. In. vitro. studies. have. sug-
gested. that. the. key. factors. responsible. for. nanoparticle. toxicity. include. the. disintegra-
tion.and.release.of.toxic.material.from.nanoparticles,.the.reactive.oxygen.species.(ROS).
generation,.and.the.surface.properties.of.nanoparticles.(Derfus.et.al..2003,.Hardman.et.al..
2006)..These.factors.should.also.be.taken.into.account.when.studying.the.biocompatibility.
of.NDs.
25.3.1 in Vitro Toxicity Studies
A.large.number.of.research.groups.have.addressed.the.in.vitro.toxicity.of.NDs.(Yu.et.al..2005,.
Schrand.et.al..2006,.2007,.Huang.et.al..2007,.Liu.et.al..2007,.2010,.Vial.et.al..2008,.Xing.et.al..
2011)..For.example,.Schrand.et.al..have.studied.in.detail.the.differential.biocompatibility.
of. carbon-based. materials. with. two. different. cell. lines,. alveolar. macrophage. and.
neuroblastoma. cells. (Schrand. et. al.. 2007).. Their. results. show. that. ND. has. a. greater.
biocompatibility. than. carbon. black. (CB),. multi-walled. carbon. nanotubes. (MWNTs),. and.
single-walled.carbon.nanotubes.(SWNTs).(Figure.25.4)..Cells.internalized.with.NDs.retain.
intact.mitochondrial.membranes.and.also.a.very.low.level.of.ROS..Additionally,.cells.that.
are. grown. on. ND-coated. substrate. display. good. viability. without. altering. their. cellular.
function.. Similarly,. Liu. et. al.. have. observed. no. signiicant. apoptosis. and. cell. death. for.
both. detonation. and. HPHT. NDs. in. lung. cells. (Liu. et. al.. 2010).. The. non-cytotoxicity. of.
detonation.NDs.(size.ranging.between.2.and.8.nm).has.further.been.conirmed.by.Huang.
et. al.. with. MTT. assays,. reverse. transcription. polymerase. chain. reaction. (RT-PCR),. and.
DNA.fragmentation.assays.(Huang.et.al..2007).
