Virus-Based Nanobiotechnology - The Nanobiotechnology - page 156

arrangement. of. the. M13. capsid. structure. allows. for. precise. control,. as. the. following.
examples.demonstrate.
Initial. nanoengineering. efforts. with. M13. used. phage. display. to. select. for. peptides.
on. the. pIII. protein. capable. of. binding. the. inorganic. semiconductor,. Gallium. Arsenide.
(GaAs)..M13.phages.expressing.a.peptide.sequence.with.high-binding.afinity.for.GaAs.
were. shown. to. self-assemble. onto. a. silicon. surface. patterned. with. GaAs. lines. (Whaley.
et.al..2000)..Another.peptide.with.speciic.binding.to.ZnS.crystal.surfaces.was.expressed.
on. the. M13. capsid,. which. upon. mixing. with. ZnS. precursors. in. solution. enabled. self-
assembly. of. ordered. two-dimensional. hybrid. ilms. (Lee. et. al.. 2002).. The. same. peptide,.
when.expressed.on.the.pVIII.protein.rather.than.pIII,.promotes.nucleation.of.ZnS.nanow-
ires.(Mao.et.al..2003)..The.material.set.templated.through.this.approach.expanded.further.
by. demonstrating. incorporation. of. peptides. that. enable. nucleation. of. semiconducting.
CdS,.and.ferromagnetic.CoPt.and.FePt.into.the.capsid..Annealing.such.samples.at.higher.
temperatures.removes.the.viral.components.and.leave.the.structured.inorganic.material.
behind.(Mao.et.al..2004).
Polymers. can. also. be. templated. using. M13.. One. approach. involves. the. process. of.
electrospinning. to. produce. aligned. nanoibers,. thereby. mimicking. the. biological.
phenomenon. of. spider. silk.. M13. phages. were. incorporated. into. a. polymeric. solution.
containing. polyvinyl. pyrrolidone. (PVP). and. extruded. through. a. micron-sized. needle.
under.high.voltage..The.resulting.nanodiameter.ibers.exhibited.high.surface-to-volume.
ratios,.and.the.M13.phage.retained.infectivity.when.dissolved.with.the.appropriate.solvent.
(Lee.et.al..2004)..A.second.approach.uses.chemical.modiication.of.the.major.coat.protein.to.
enable.polymerization.on.the.exterior..By.coating.the.virus.with.polyacrylamide,.the.phages.
self-assembled. into. bundles. or. ibers. in. solution. and. exhibited. gel-like. characteristics.
without.the.need.of.a.cross-linker.(Willis.2008).
Alternatively,. ordered. structures. can. be. realized. by. genetic. modiications. to. the.
opposing.end.capping.proteins.pIII.and.pIX..Such.a.strategy.enabled.researchers.to.cre-
ate. size-controlled. nanorings. (Figure. 7.6).. One. capping. protein. was. made. to. express. a.
streptavidin-binding.peptide,.while.the.distal.protein.expressed.a.hexahistidine.peptide..
200 nm
Figure 7.6
(See companion CD for color igure.) . AFM. image. of. an. M13. nanoring.. (Reprinted. with. permission. from.
Nam,.K.T.,.Peelle,.B.R.,.Lee,.S.-W.,.Belcher,.A.M.,.Genetically.driven.assembly.of.nanorings.based.on.the.M13.
virus,. Nano Lett .,.4(1),.23-27..Copyright.2004.American.Chemical.Society.)