Biomedical Engineering Reference
In-Depth Information
of.anodic.alumina.membranes..Carbon.nanotubes.are.an.example.of.a.structure.capable.of.
growing.out.of.the.pores.in.AAMs..Alumina.has.also.been.employed.for.tissue.engineering.
through.construction.of.a.biocompatible,.nanoporous.anodic.aluminum.oxide.membrane.
(Poinern. et. al.. 2011).. Nanoporous. alumina. membranes. modiied. with.
n
-alkanoic. acids.
have.also.been.developed.for.use.in.protein.adsorption.(Chang.and.Suen.2006).
Other.metal.oxides.such.as.nickel.oxide.and.zinc.oxide.are.also.used.in.nanobiotechnol-
ogy. in. biosensors,. magnetic. bioseparations,. as. well. as. protein. and. cell. adsorption.. Zinc.
oxide. thin. ilms. have. been. used. for. hydrogen. peroxide. sensing. (Sivalingam. et. al.. 2011)..
In.a.study.conducted.by.Mu.et.al..(2007),.nickel.oxide.was.used.for.nonenzymatic.glucose.
sensing.
15.2.2 Carbon
Carbon.comes.in.many.different.forms,.referred.to.as.allotropes..Carbon.nanotubes.and.
graphene.are.just.two.of.the.many.allotropes.of.carbon..Figure.15.1.illustrates.the.different.
structures.carbon.can.take,.as.well.as.explaining.carbon's.unique.properties..Similar.to.the.
differences.between.diamond.and.graphite,.carbon.nanotubes.(CNTs).and.graphene.have.
different.properties.from.each.other.as.well.as.from.their.pure.elemental.parent,.carbon..
The.difference.in.their.properties.allows.for.a.wider.variety.of.applications.
15.2.2.1 Carbon Nanotubes
CNTs.were.irst.discovered.in.1991.and.have.been.of.great.interest.ever.since..These.struc-
tures.have.intriguing.characteristics.(chemical.stability,.high.surface.area,.and.easy.size.
manipulation).that.allow.for.CNTs.to.have.many.different.biological.applications.includ-
ing.transport.of.biomolecules,.biosensing,.and.cell.culture.
There. are. many. different. kinds. of. biological. sensing. that. employ. CNTs.. Often. CNTs.
are.combined.with.biological.structures.to.allow.for.better.biocompatibility..In.one.case,.
single-walled.CNTs.were.coated.with.double-stranded.DNA.(dsDNA).for.use.in.the.sens-
ing. of. hydrogen. peroxide. and. glucose. (Xu. et. al.. 2011).. These. single-walled. CNTs. were.
coated. with. dsDNA,. which. allows. for. the. solubilization. of. the. CNTs. to. make. a. stable.
suspension.in.aqueous.solution..Without.the.dsDNA,.the.CNTs.would.align.themselves.
and. it. would. be. dificult. to. get. them. to. disperse. (Dresselhaus. et. al.. 1996).. CNTs. illed.
with. a. membrane. composed. of. poly(acrylonitrile-
co
-acrylic. acid). (PANCAA). have. also.
been.used.for.glucose.biosensing.(Wang.et.al..2011)..PANCAA.and.a.multiwalled.CNT.
were. electrospun. together. onto. a. platinum. electrode,. and. glucose. oxidase. was. then.
immobilized.onto.the.PANCAA.membrane..Another.approach.to.glucose.biosensing.was.
achieved.by.electrodepositing.palladium.nanoparticles,.along.with.glucose.oxidase,.on.
to.a.Naion-solubilized.carbon.nanotube.electrode.(Lim.et.al..2005)..Naion.is.a.biocom-
patible,. synthetic. copolymer. with. unique. ionic. properties,. and. it. has. been. previously.
reported. that. this. copolymer. is. a. good. solubilizing. agent. for. CNTs. (Wang. et. al.. 2003)..
Being.able.to.dissolve.CNTs.in.Naion.allows.for.easy.manipulation.for.modifying.elec-
trode.surfaces.for.biosensors..Thin.ilms.of.CNTs.have.been.designed.and.tested.for.DNA.
electrochemical.sensing.(Berti.et.al..2009).
The. use. of. CNTs. in. cell. culture. and. cell. growth. has. also. become. of. interest.. CNTs.
are.being.studied.for.these.purposes.because.they.can.be.easily.aligned.and.oriented.in.
speciic.ways.in.order.to.manipulate.the.cells.to.grow.a.certain.way,.as.well.as.providing.
nanotopography..Patterned.CNTs.also.help.with.cell.adhesion.onto.the.tubes.(Abdullah.
et.al..2011).
