Biomedical Engineering Reference
In-Depth Information
as.0.01.induced.signiicant.alignment.(60%),.the.maximum.aspect.ratio.required.for.95%.
alignment.was.0.16.(Crouch.et.al..2009)..Similarly,.a.complementary.study.by.Lamers.et.al..
(2010).identiied.a.ridge-to-groove.ratio.of.1:3.and.a.pitch.of.400.nm.as.being.optimal.for.
maximum.osteoblast.motility.
Studies. show. that. cellular. cytoskeletal. and. adhesion. complex. alignment. is. generally.
more. pronounced. on. patterns. with. ridge. widths. between. 1. and. 5. μm. than. on. grooves.
and.ridged.topographies.with.larger.lateral.dimensions.(denBraber.et.al..1998;.Matsuzaka.
et.al..2000;.Teixeira.et.al..2003;.Karuri.et.al..2004).and.that.cells.cultured.on.grooves.with.
nanoscale.widths.produce.focal.adhesions.that.are.almost.exclusively.oriented.obliquely.to.
the.topographic.patterns.(Teixeira.et.al..2006)..This.occurs.predominantly.on.topographi-
cal.ridges.as.opposed.to.grooves,.effectively.limiting.the.length.of.focal.adhesions.formed.
perpendicular.to.the.groove.orientation..Thus,.it.arises.that.grooved.nanoscale.topogra-
phies.can.inluence.both.adhesion.direction.as.well.as.adhesion.reinforcement.
Studies.thus.far.suggest.that.as.with.protrusions.and.pits,.a.critical.groove.depth.of.
34.nm.is.required.for.contact.guidance.to.occur.and.that.contact.guidance.is.not.initi-
ated.on.groove.depths.below.∼34.nm.(Biela.et.al..2009).or.ridge.widths.less.than.100.nm.
(Loesberg. et. al.. 2007).. Similarly,. contact. guidance. or. a. modulation. in. focal. adhesion.
formation. is. not. initiated. on. anisotropic. grooved. topographies. with. feature. widths.
are.signiicantly.greater.than.that.of.the.cellular.diameter..Such.topographies,.it.can.be.
argued,.are.essentially.planar.areas.separated.by.a.topographical.step.that.neither.per-
turb.integrin.activation.and.clustering.nor.offer.an.increased.surface.area.to.facilitate.
focal.adhesion.formation..For.a.schematic.explanation.see.Figure.20.7.
(a)
(b)
(c)
(d)
Figure 20.7
(See companion CD for color igure.)
. Inluence. of. nanoscale. grooves. on. focal. adhesion. formation. and.
re-enforcement..(a).Integrin.clustering.and.focal.adhesion.re-enforcement.are.unaffected.on.nanoscale.grooves.
with.a.critical.depth.of.<34.nm..(b).Increasing.the.feature.height.restricts.integrin.clustering.and.focal.adhesion.
formation.at.the.sites.of.nanoscale.grooves..Focal.adhesions.are.restricted.to.the.ridge.apexes..(c).Integrin.clus-
tering.and.focal.adhesion.formation.are.greatly.perturbed.on.nanoscale.ridges.with.widths.<73.nm,.in.a.manner.
similar.to.nanoscale.protrusions..(d).Low.aspect.ratio.features.(>100.nm.width).do.not.initiate.contact.guidance.
alignment..However,.focal.adhesion.reinforcement.is.perturbed.by.the.groove.width.
