Biomedical Engineering Reference
In-Depth Information
lattened.origami.design.to.explore.pi.stacking.as.an.assembly.interaction..By.combining.
geometric.patterning.(“pegs”.and.“holes”).with.pi.stacking,.groups.of.up.to.ive.origami.
could.be.assembled.in.speciic.order.and.with.good.control.over.orientation.
1.6.6 Biomedical Applications
There. are. a. range. of. possible. applications. for. DNA. nanostructures. in. biomedicine..
Reconigurable. DNA. nanostructures. may. be. useful. as. a. tool. or. jig. to. grip,. push,. or. pull.
other. biomolecules.. For. example,. an. M13. mp18. DNA. origami. in. the. shape. of. a. picture.
frame.(80.×.90.nm.with.a.hole.40.×.40.nm).was.used.to.stretch.64-.and.74-mer.duplex.DNA.
test.strands..The.stretched.and.relaxed.duplexes.were.allowed.to.react.with.M..
Eco
RI.and.
observed.in.situ.by.a.one.frame/second.fast.scanning.solution.AFM.(Endo.et.al..2009)..There.
are. other. applications. for. DNA. nanostructures. that. offer. diagnostic. utility..A. nanoscopic.
analog. of. DNA. microarray. chips. for. detection. of. RNA. sequences. was. constructed. by.
displaying.rows.of.capture.probes.on.a.60.×.90.nm.DNA.origami.(Ke.et.al..2008)..In.the.absence.
of.the.targeted.RNA.strand,.the.capture.probes.are.ss.and.loppy;.hybridization.to.the.target.
RNA.strand.causes.formation.of.a.relatively.rigid.DNA-RNA.helix,.which.can.be.imaged.
by.AFM.as.a.bright.spot.on.the.DNA.origami..Hybridization.was.selective.in.the.presence.
of.2.mg/mL.total.cellular.RNA..The.advantage.of.label-free.detection.with.high.sensitivity.
must.be.balanced.against.the.need.for.AFM.visualization.of.the.DNA.devices..DNA.origami.
are.larger.than.most.virus.particles,.and.they.can.be.used.as.structural.templates.to.assemble.
ordered. arrays. of. proteins. (Chhabra. et. al.. 2007). or. viruses. (Stephanopoulos. et. al.. 2010)..
Virus.capsids.of.bacteriophage.MS2.(27.nm.diameter,.180.subunits).were.decorated.with.a.
coating. of. about. 20. DNA. oligonucleotides. through. conjugation. at. unnatural. amino. acids.
inserted.via.genetic.engineering.on.the.exterior.of.the.capsids..Several.capture.oligos.were.
included.on.each.DNA.origami.to.hybridize.with.the.target.oligos.on.the.capsids,.and.high.
capture. rates. (>97%). were. observed.. 1D. arrays. were. formed. by. adding. ss. DNA. linkers,.
either. between. origami. carrying. viral. capsids. and. their. neighboring. origami. or. between.
origami.and.the.virus.capsid/DNA.structure..Annealing.from.37°C.to.4°C.at.1°C/m.resulted.
in.at.least.50%.of.the.DNA.origami.being.present.in.short.1D.oligomers..Longer.annealing.
times. gave. a. higher. degree. of. oligomerization. in. the. absence. of. the. capsids,. but. in. the.
presence.of.the.capsids.(or.if.capsids.were.added.after.oligomerization),.aggregation.was.
the.main.outcome..The.multiple.target.oligos.on.each.capsid.could.interact.with.multiple.
DNA.origami,.and.this.probably.caused.the.aggregation.problem.
Many.of.the.3D.DNA.nanostructures.have.been.suggested.as.smart.carriers.for.drugs,.
imaging.agents,.enzymes,.or.virus.particles..A.recent.spate.of.studies.suggest.that.DNA.
nanostructures.have.at.least.a.few.days.of.stability.in.biological.milieux.that.contain.live.
cells,.enzymes.capable.of.degrading.DNA,.and.proteins.that.can.bind.nonspeciically,.so.
these.kinds.of.applications.are.feasible.(Liu.et.al..2011,.Mei.et.al..2011,.Walsh.et.al..2011)..
A.recent.report.describes.the.use.of.a.“clamshell”.illed.with.bioactive.proteins,.where.the.
“shell”.is.held.closed.by.DNA.aptamers..The.aptamers.recognize.and.bind.to.speciic.cell.
types,.causing.the.clamshell.to.open.and.releasing.proteins.that.initiate.programmed.cell.
death.(Douglas.et.al..2012).
1.6.7 Surface Deposition
For.many.electronic.or.sensor.applications,.it.would.be.desirable.to.interface.DNA.origami.
with. complementary. metal. oxide. semiconductor. (CMOS). structures. on. semiconductor.
