Biomedical Engineering Reference
In-Depth Information
(a)
(b)
(c)
(d)
Figure 20.5
(See companion CD for color igure.)
. Inluence. of. nanoscale. protrusions. on. focal. adhesion. formation. and.
re-enforcement.. (a). Integrin. clustering. and. focal. adhesion. re-enforcement. are. not. signiicantly. affected.
by. nanoscale. protrusions. with. a. critical. spacing. of. <73.nm.. (b). Increasing. the. interfeature. spacing. to. the.
>73.nm.reduces.integrin.clustering,. and.focal.adhesion.reinforcement..(c).Integrin. clustering.and.focal.adhe-
sion. re-enforcement. are. not. signiicantly. affected. by. nanoscale. protrusions. with. a. critical. height. of. <34.nm..
(d). Integrin. clustering. and. cellular. adhesion. are. greatly. perturbed. on. nanoscale. protrusion. with. a. feature.
diameter.of.<73.nm.and.an.interfeature.distance.>73.nm.
20.6 Effects of Nanoscale Pits on Focal Adhesion Formation
As. with. nanoscale. protrusions,. the. fabrication. of. high-resolution. and. high-symmetry.
nanopit. topographies. has. beneited. greatly. from. the. advent. of. high-resolution. writing.
techniques.such.as.EBL.and.dip-pen.nanolithography..Yet.less.ordered.topographies.can.
be. fabricated. via. self-organization. techniques,. such. as. polymer. phase. separation. and.
anodic.oxidation.to.rapidly.produce.large-area.nanotopographic.pit.substrates.for.assess-
ing.the.cellular.response.to.these.features.
Nanopores.are. identiied.as. common. constituents.of.tissues.in. vivo,. notably. the.base-
ment.membrane.of.the.cornea.(Abrams.et.al..2000),.the.aortic.heart.valve.(Brody.et.al..2006),.
and.the.vascular.system.(Liliensiek.et.al..2009),.and.may.be.implicated.in.the.regulation.
of.cell.behavior.and.function..Pitted.topographies.have.been.shown.to.produce.differing.
effects.on.cellular.adhesion.in.vitro,.depending.on.pit.diameter.and.the.spacing.and.sym-
metry.of.pit.positioning.(Biggs.et.al..2007;.Dalby.et.al..2008a).
Currently,.the.majority.of.experimental.evidence.indicates.that.the.spacing.and.density.
of.nanopit.features.are.as.inluential.as.the.feature.dimensions.on.focal.adhesion.forma-
tion.when.fabricated.in.the.nanoscale.(Table.20.2)..Studies.indicate.that.cells.can.respond.
signiicantly. to. small. changes. in. the. order. of. nanopit. spacing. and. that. modulating. the.
order.of.pit.conformation.signiicantly.affects.both.cellular.adhesion.and.cellular.function.
