Biomedical Engineering Reference
In-Depth Information
a.porous.stamp.to.obtain.a.permanent.hydrophilic.surface.to.print.high.molecular.weight.
materials.
30
. They. fabricated. hydrophilic. porous. stamps. using. a. phase. separation. micro-
molding.process,.and.demonstrated.µCP.by.printing.proteins.several.times.without.reink-
ing..Foley.et.al..developed.an.interesting.technique.to.print.proteins.inside.recessed.areas,.
such.as.bottom.surfaces.of.microchannels,.which.was.possible.by.bending.a.PDMS.stamp.
itself.
31
.Microcontact.printing.has.been.employed.for.differentiation.study,.where.gene.and.
protein.analysis.of.micropatterned.human.ESCs.revealed.that.endodermal.and.neuronal.
expression.increased.inversely.with.colony.size.
13
12.2.3 Other Techniques
There.are.many.other.techniques.to.make.selective.biological.patterns.on.substrates..For.
example,.with.the.use.of.microluidic.channels,.luids.can.be.conined.on.a.surface.to.control.
cell.interaction.with.materials.selectively.
32
.By.expanding.this.technique,.Takayama.and.co-
workers.studied.how.laminar.low.can.establish.a.single.stream.consisting.of.two.or.more.
luids,.which.can.establish.a.subcellular.microenvironment.by.positioning.a.single.mam-
malian.cell.at.the.interface.between.two.different.streams.
33
.Also,.Ostuni.et.al..developed.
a.PDMS.stencil.patterning.that.is.straightforward.in.that.it.requires.no.chemical.treatment.
of. the. surface.
34
. They. fabricated. a. cell-repellent. PDMS. stencil. by. coating. the. stencil. with.
bovine.serum.albumin.(BSA),.and.then.attached.the.PDMS.stencil.on.a.substrate.to.culture.
bovine.capillary.endothelial.(BCE).cells.selectively..Direct.forming.of.liquid.phase.cell.pat-
terns.by.dispensing.nanoliter.volumes.was.developed.by.Tavana.et.al..to.sustain.aqueous.
environments. during. pattern. formation. (Figure 12.3).
35
. Aqueous. dextran. was. dispensed.
(a)
(b)
FIGURE 12.3
Nanoliter.liquid.patterning.in.an.aqueous.environment.(b)..Dispensing.reagent.of.interest.in.the.aqueous.envi-
ronment.ensures.high.reagent.activity.and.cell.viability.as.well.as.patterning.lexibility.for.investigating.differ-
ent.microenvironments.between.adjacent.cells.(a)..Adapted.with.permission.from.reference.35..Copyright.2009.
Macmillan.Publishers.Ltd:.Nature.Materials.
