Biomedical Engineering Reference
In-Depth Information
the.possibility.that.physical.cues.alone.could.profoundly.impact.differentiation.capacity.
(Brammer.et.al..2011a).
8.3.2 Pits
Akin.to.nanopillar.height,.nanopit.depth.has.been.shown.to.elicit.varied.cell.responses..In.
one.study,.Sutherland.et.al..generated.nanopits.(40.nm.diameter,.10.nm.depth).on.gold.and.
TiO
2
. materials,. and. functionalized. several. surfaces. with. ibrinogen.. At. earlier. time. points,.
human.platelets.bound.to.substrates.having.both.nanopits.and.ibrinogen.more.rapidly.than.
their. lat. counterparts.. But. with. time,. all. gold. surfaces—regardless. of. whether. physically.
or. chemically. modiied—exhibited. greater. platelet. density. than. TiO
2
.. Overall,. this. study.
noted.the.transition.in.cell.behavior.from.reliance.on.physical.topography.to.that.of.surface.
chemistry.(Sutherland.et.al..2001)..Assessing.human.ibroblast.interactions.on.PCL.substrates.
containing. nanopits. (35,. 75,. 120.nm. diameter),. noted. more. limited. cell. spreading. and. less.
cytoskeletal.organization.with.a.decrease.in.nanopit.size.(Figure.8.6)..Interestingly,.ilopodia.
numbers. rose. with. larger-diameter. nanopits,. implying. that. cells. more. actively. sense. their.
environment.due.to.perturbation.(Dalby.et.al..2004a)..Similar.cell.behavior.was.observed.in.
bone.marrow.MSCs.seeded.onto.poly(carbonate).with.120.nm.pits.arranged.in.either.a.square.
or.hexagonal.coniguration..The.latter.had.greater.inhibition.of.adhesion.and.resulted.in.more.
structural.disorder.(Hart.et.al..2007)..Indeed,.changing.nanopit.diameter.could.act.as.a.means.
of.modulating.cell-substrate.interactions.and.further.downstream.events.
A.fundamental.aspect.involves.understanding.of.topographical.effects.in.the.presence.of.
more.than.one.nanopattern..Seunarine.et.al..fabricated.four.different.silicon.surface.patterns.
using.nanopits.and.microgratings..Commercially.available.human.ibroblasts.(hTERT).had.
strong.afinity.for.lines.of.nanopits,.preferentially.arranging.themselves.within.this.region.
rather.than.on.lat,.adjacent.portions..On.a.substrate.with.both.nanopits.and.microgratings,.
cell.alignment.was.also.shown.to.be.more.heavily.inluenced.by.the.former..These.indings.
demonstrated.that.certain.nanopatterns.take.precedence.over.others.and.may.thereby.con-
trol.cellular.behavior.via.different.mechanisms.(Seunarine.et.al..2009).
8.3.3 grooves
Teixeira. et. al.. observed. human. corneal. epithelial. cell. growth. on. silicon. oxide. surfaces.
nanopatterned.with.grooves.(400-4000.nm.pitch—including.ridges,.150.or.600.nm.depth;.
Figure.8.6)..These.cells.displayed.spindle-like.morphology.and.alignment.with.the.modi-
ied.substrate.down.to.a.groove.width.of.70.nm..Focal.adhesions.and.stress.ibers.oriented.
along.the.grooves.and.ridges.experienced.limited.spreading.dictated.by.nanofeature.size,.
whereas.no.such.inhibition.occurred.on.nonpatterned.surfaces..Among.their.key.indings,.
the.authors.revealed.that.groove.depth.impacted.cell.alignment.to.a.greater.extent.than.
pitch.(Teixeira.et.al..2003)..Depth.was.demonstrated.in.a.later.work.to.be.the.most.crucial.
parameter.on.the.inluence.of.cell.alignment.(Loesberg.et.al..2007)..The.Sutherland.group.
fabricated. nanogrooved. titanium-coated. silicon. wafers. for. culture. of. mouse. mammary.
epithelial. cells.. It. was. noted. that,. given. the. choice,. these. cells. preferentially. adhered. to.
planar.surfaces..Two.conigurations.(continuous.or.discontinuous.edges).of.nanopatterned.
surfaces. indicated. that. continuous. edges. more. effectively. facilitated. cell. alignment. and.
focal.contact.establishment.(Andersson.et.al..2003).
In.another.study,.human.primary.osteoblasts.were.grown.on.PMMA.surfaces.contain-
ing.grooves.(330.nm.depth;.10,.25,.or.100.μm.width)..Nanofeature.width.proved.crucial.in.
