Biomedical Engineering Reference
In-Depth Information
chloride. solution,. resulting. in. iridium. oxide. nanocrystals. colocalized. with. porphyrins.
along. the. virus. capsid.. Photocatalytic. production. of. oxygen. was. enhanced. when. com-
pared.to.iridium-coated.viruses.in.the.presence.of.zinc.porphyrins.in.the.solution.(Nam.
et.al..2010a).
Dye-sensitized. solar. cells. (DSSCs). represent. another. application. in. which. the.
nanobioengineering. of. viruses. holds. potential. for. improvement.. Nanoporous. DSSCs.
are. desirable. due. to. lower. fabrication. costs. than. traditional. silicon. solar. cells,. but. are.
plagued.by.low.power-conversion.eficiencies..Researchers.have.shown.that.incorporating.
single-wall. carbon. nanotubes. (SWNTs). into. DSSCs. can. improve. the. power-conversion.
properties,.but.the.natural.tendency.of.SWNTs.to.aggregate.reduces.the.beneits.of.the.extra.
processing.associated.with.their.use..Recently,.M13.bacteriophages.have.been.engineered.
to. express. an. SWNT. binding. peptide. on. the. pVIII. protein. to. prevent. SWNT. bundling..
The.SWNT-M13.phages.were.used.as.biotemplates.for.the.nucleation.and.growth.of.TiO
2
.
nanoparticles,.and.incorporated.into.nanoporous.DSSCs..Annealing.these.hybrid-DSSCs.
at.high.temperatures.effectively.removed.the.original.phage.templates.with.no.negative.
impacts.on.performance..The.result.is.the.incorporation.of.SWNT.into.DSSCs.with.reduced.
bundling.effects.and.increased.power-conversion.eficiencies.(Dang.et.al..2011).
As. with. the. preceding. applications,. engineering. of. M13. bacteriophages. poses. a.
particular.interest.owing.to.their.nanoscale.dimensions.in.conjunction.with.compatibility.
with.a.wide.variety.of.material.sets..The.ultimate.goal.of.alternative.energy.technologies.
relies.on.high-eficiency.operation,.which.can.be.enhanced.through.the.use.of.biological.
templating.and.increased.surface-to-volume.ratios.of.catalytic.components..Extending.the.
material.nucleation.examples.mentioned.earlier,.M13.phages.that.express.cobalt-nucleating.
peptides.have.been.incorporated.into.lithium.ion.batteries..The.phages.were.used.to.grow.
cobalt. oxide,. a. material. with. increased. energy. storage. capabilities. versus. traditional.
carbon-based. battery.components. (Nam.et.al..2006)..Such.cobalt-coated.M13.phages.can.
be.integrated.into.microbatteries.through.a.process.that.combines.traditional.top-down.
fabrication. with. bottom-up. biotemplating. (Nam. et. al.. 2008).. M13. bacteriophages. have.
even.been.utilized.as.a.biological.scaffold.for.metal.nucleation.in.hydrogen-producing.fuel.
cells.(Neltner.et.al..2010)..For.this.application,.a.short.peptide.sequence.containing.three.
glutamic.acid.residues.was.expressed.on.the.surface.of.the.pVIII.coat.protein..At.neutral.
pH,.the.residues.are.negatively.charged,.and.attract.metal.ions.in.solution,.resulting.in.the.
nucleation.and.growth.of.cerium.oxide.nanocrystals.with.nickel.and.rhodium.impurities..
The.nanocrystalline.CeO
2
.acts.as.a.catalyst.in.the.hydrogen.conversion.reaction,.and.the.
phage-biotemplated.nanostructures.exhibited.reduced.deactivation.over.time.
The. increased. reliance. on. alternative. energy. technologies. in. the. near. future. will.
almost.certainly.beneit.from.nanotechnological.advances,.and.quite.possibly.from.virus.
nanobiotechnology.
7.4 MS2 Bacteriophage
7.4.1 general Properties, Structure, and Assembly
The. MS2. bacteriophage. is. an. icosahedral,. nonenveloped. virus. in. the. family.
Leviviridae
.
that. has. been. extensively. studied. and. engineered. over. the. past. 40. years.. Isolated. in. the.
early.1960s,.the.gene.encoding.the.capsid.protein.was.the.irst.to.have.its.entire.nucleotide.
sequence.identiied.(Min.Jou.et.al..1972),.and.MS2.was.also.the.irst.organism.to.have.its.
