Biomedical Engineering Reference
In-Depth Information
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(a)
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Figure 7.10
(See companion CD for color igure.)
. Modiication. of. CPMV. capsids. with. gold. nanoclusters.. (a). Unstained.
TEM.image.of.gold.nanoparticles.bound.to.a.mutant.CPMV.virus..(b).Model.of.mutant.CPMV.with.gold.par-
ticles.bound.to.all.sites..(c).Unstained.isolated.mutant.with.42.visible.2.nm.gold.particles.bound.to.it..(d).Model.
of. the. mutant. with. gold. particles. bound. to. all. sites.. All. scale. bars. are. 5.nm.. (Adapted. with. permission. from.
Blum,.A.S.,.Soto,.C.M.,.Wilson,.C.D.,.Cole,.J.D.,.Kim,.M.,.Gnade,.B.,.Chatterji,.A.,.Ochoa,.W.F.,.Lin,.T.,.Johnson,.J.E.,.
Ratna,.B.R.,.Cowpea.mosaic.virus.as.a.scaffold.for.3-D.patterning.of.gold.nanoparticles,.
Nano Lett
.,.4(5),.867-870..
Copyright.2004.American.Chemical.Society.)
dip-pen.nanolithography.(DPN).(Cheung.et.al..2003,.Smith.et.al..2003)..In.this.approach,.
alkanethiols.are.patterned.onto.gold.surfaces.by.DPN,. and.then.chemically. modiied. to.
present.maleimides.at.their.distal.end..The.maleimides.then.react.with.cysteine-modiied.
CPMV.particles.to.produce.the.viral.nanotemplates.
It. is. also. possible. to. modify. native. lysine. residues. on. the. capsid. exterior. via. NHS-
esters..Although.several.lysine.residues.are.available.on.the.surface,.it.is.feasible.to.con-
jugate. only. one. lysine. per. asymmetric. unit. at. pH. 7.0. (Wang. et. al.. 2002a).. However,. an.
alternative.is.to.preferentially.address.a.single.lysine.per.asymmetric.unit.by.using.site-
directed.mutagenesis.to.convert.the.other.lysine.residues.to.arginines.without.negative.
impact.on.capsid.stability.(Chatterji.et.al..2004)..Other.modiication.approaches.involve.
short. peptide. insertions. of. 6-histidine. sequences. onto. the. surface. of. CPMV,. enabling.
capsid. decoration. with. metal-coordinated. linking. chemistries.. Researchers. have. used.
6H. peptide. sequences. to. decorate. the. capsid. with. both. CdSe. quantum. dots,. and. gold.
nanoparticles. (Chatterji. et. al.. 2005,. Medintz. et. al.. 2005).. Other. functional. groups. can.
also. be. targeted. through. chemical. modiication. approaches.. For. instance,. oxidation. of.
tyrosine.residues.on.the.capsid.surface.allowed.for.the.functionalization.of.CPMV.with.
luorophores. (Meunier. et. al.. 2004).. Carboxylate. groups. on. surface-exposed. aspartic.
