Biomedical Engineering Reference
In-Depth Information
and.glutamic.acid.residues.can.also.be.used.for.chemical.conjugation.(Steinmetz.et.al..
2006)..These.carboxylate.groups.have.been.used.to.attach.approximately.180.redox.active.
methyl. viologen. moieties. to. the. capsid. exterior.. The. ability. to. differentially. address.
unique. reactive. groups. on. the. capsid. exterior. using. different. linking. chemistries. has.
facilitated.double.labeling.of.the.capsid.and.has.made.CPMV.an.attractive.candidate.for.
a.host.of.nanobiological.applications.
In.parallel.with.chemical.and.genetic.modiications.for.functionalization.of.CPMV.viri-
ons,.a.large.body.of.work.has.been.published.that.takes.advantage.of.the.well-characterized.
ability. of. CPMV. to. present. foreign. peptides. on. its. surface.. Most. peptide. insertions. are.
located.on.the.small.subunit,.on.a.loop.that.is.exposed.at.the.distal.end.of.the.ivefold.sym-
metry. protrusion.. In. this. fashion,. short. peptide. sequences. known. to. nucleate. inorganic.
materials,.such.as.silica.and.FePt,.has.been.inserted.that.produce.virus-templated,.mono-
disperse.nanoparticles.(Shah.et.al..2009,.Steinmetz.et.al..2009)..However,.it.quickly.became.
evident. that. genetically. prepared. CPMV. chimeras. cannot. effectively. present. peptides.
known.to.nucleate.other.inorganic.compounds..As.a.result,.researchers.have.returned.to.
modiication.techniques.where.the.nucleating.peptides.are.chemically.conjugated.to.lysine.
residues.on.the.CPMV.exterior..As.a.result,.nucleation.of.CoPt.and.ZnS.nanoparticles.has.
been.realized.(Aljabali.et.al..2011b).
The. robustness. of. CPMV. also. makes. it. possible. to. deposit. metal. compounds. directly.
onto.the.capsid.surface..Lysine.residues.on.wild-type.CPMV.virions.could.be.preactivated.
with.palladium.at.pH.3.8,.followed.by.electroless.deposition.(ELD).of.a.host.of.metal.com-
pounds. including,. but. not. limited. to,. NiFe. and. CoPt. (Aljabali. et. al.. 2010).. Alternatively,.
it.has.been.shown.that.gold.nanoparticles.can.be.templated.from.CPMV.capsids.by.irst.
encapsulating.the.virion.with.the.polyelectrolyte,.poly(allylamine).hydrochloride.(PAH)..
At. neutral. pH,. CPMV. capsids. present. a. negative. charge,. thus,. promoting. adsorption. of.
the. cationic. polyelectrolyte. onto. the. surface.. Subsequent. reduction. of. a. gold. precursor.
resulted.in.gold-coated.CPMV.virions.(Aljabali.et.al..2011a).
7.5.3 Diagnostics and imaging
CPMV.offers.researchers.an.array.of.modiication.approaches.for.use.in.the.ield.of.nano-
biotechnology..Although.examples.exists,.it.is.a.little.surprising.that.CPMV.has.not.been.
explored.in.nanobiotechnology.applications.such.as.targeted.delivery.and.biosensing.to.a.
greater.degree.
CPMV.has.been.demonstrated.as.a.potential.tool.for.the.delivery.of.diagnostic.agents..
In.one.study,.luorophores.were.conjugated.to.lysine.residues.on.the.CPMV.exterior,.and.
the. resulting. conjugates. were. injected. into. the. tails. of. mice.. These. CPMV-luorophore.
constructs. could. then. be. used. to. image. vasculature. and. the. angiogenesis. occurring. in.
developing. tumors. (Lewis. et. al.. 2006).. It. has. also. been. shown. that. luorophore-labeled.
CPMV.capsids.can.be.retained.in.endothelial.tissue.for.several.days.allowing.long-term.
imaging.(Leong.et.al..2010)..Also,.dually.modiied.CPMV.capsids.have.been.used.to.pro-
vide. site-speciic. labeling. in. immunoassays.. CPMV. virions. possessing. an. introduced.
cysteine. were. modiied. irst. with. approximately. 60. luorophores. through. thiol-linking.
chemistries,.followed.by.conjugation.of.an.antibody.to.surface.lysines.with.NHS.esters..
The.resulting.immunolabeled.luorescent.viral.particles.improved.the.limit.of.detection.
of.
Staphylococcus aureus
.enterotoxin.B.(SEB).(Sapsford.et.al..2006)..Fluorescent.dye-labeled.
CPMV.particles.have.also.been.demonstrated.to.increase.the.sensitivity.of.commercially.
available.DNA.microarrays.(Soto.et.al..2009).
