Biomedical Engineering Reference
In-Depth Information
Graphene. FET. devices. have. been. constructed. for. living. cell. detection,. while. graphene.
FRET. biosensors. are. being. used. for. the. detection. of. DNA. (Wang. et. al.. 2011).. Graphene.
can. be. easily. biofunctionalized. with. a. variety. of. biomolecules. because. of. its. large. two-
dimensional.aromatic.structure.(Wang.et.al..2011)..This.structure.permits.proteins,.such.
as.enzymes,.to.be.immobilized.on.the.surface.(Zhang.et.al..2010b)..Graphene.is.also.being.
utilized.in.cancer.research,.particularly.for.cancer.imaging.(Wang.et.al..2011).
In.a.study.conducted.by.Wang.et.al.,.graphene.oxide.was.utilized.to.construct.an.aptamer-
carboxyluorescein. (FAM)/graphene. oxide. nanosheet. (GO-nS). nanocomplex.. This. gra-
phene.oxide.nanocomplex.was.then.used.to.investigate.its.ability.to.deliver.DNA.to.the.
cells.as.well.as.molecularly.target.or.“probe”.living.cells.in.situ.for.real-time.biosensing.
(Wang.et.al..2010)..This.was.accomplished.by.coupling.ATP.to.the.aptamer-FAM/GO-nS.
complex..This.coupling.reaction.allowed.for.the.release.of.the.ATP.and.the.aptamer-FAM.
from.the.GO-nS,.the.cells.to.take.up.the.newly.formed.ATP/aptamer-FAM.complex.
Diamond,.another.well-known.form.of.carbon,.is.also.being.examined.for.use.as.a.bio-
logical.substrate..Diamond.surfaces.are.being.investigated.more.for.their.use.in.biomedi-
cal.applications,.in.particular,.chemically.vapor.deposited.(CVD).diamond..CVD.diamond.
is.inert.and.hemocompatible,.which.makes.it.biocompatible.in.the.human.body..The.pro-
cess.of.chemical.vapor.deposition.allows.for.a.very.thin.layer.of.diamond.to.be.coated.onto.
another.substrate,.such.as.silicon,.making.the.use.of.diamond.much.more.cost.effective..
To.demonstrate.this,.a.study.was.performed.in.which.Chinese.hamster.ovary.(CHO).cells.
were. grown. on. both. hydrogen-terminated. and. oxygen-terminated. CVD. diamond. sub-
strates.(Smisdom.et.al..2009)..They.found.that.the.CHO.cells.could.grow.on.the.diamond.
surfaces.while.still.maintaining.high.cell.viability.
15.2.3 Polymers
A. polymer. is. a. macromolecule. composed. of. smaller,. repeating. structural. units. called.
monomers.. Monomers. form. polymers. in. a. process. called. polymerization.. Polymers. are.
very. diverse,. being. composed. from. both. natural. and. synthetic. materials,. and. typically.
have.a.very.high.molecular.weight..There.are.many.different.types.of.polymers.includ-
ing. naturally. occurring. biopolymers.. Some. of. these. biopolymers. include. nucleic. acids,.
proteins,.carbohydrates,.and.lipids..Table.15.1.shows.the.structures.of.different.monomers.
and.their.polymers,.which.directly.correlates.to.their.chemical.and.physical.properties.
Polymers.are.now.widely.used.for.many.nanobiotechnology.purposes..Both.synthetic.
and.naturally.occurring.polymers.have.found.their.places.in.this.ield..There.are.several.
types.of.synthetic,. biocompatible.polymers.including.hydrogels.and.PDMS..A.naturally.
occurring.biocompatible.polymer.receiving.increased.attention.is.chitin/chitosan..All.of.
these.polymers.have.a.wide.variety.of.possible.applications.including.detection/biosens-
ing,.protein.binding,.microluidic.devices.for.extractions,.membranes.for.cell.culture,.and.
antimicrobial.applications.
15.2.3.1 Hydrogels
A.hydrogel.is.a.polymer.that.is.cross-linked.into.a.three-dimensional.network,.forming.a.
gel.when.exposed.to.particular.stimuli..Hydrogels.are.capable.of.absorbing.large.amounts.
of.water,.which.makes.them.desirable.for.biological.applications.(Robert.2000)..These.poly-
meric.networks.can.be.classiied.as.nonresponsive.gels.or.responsive.gels..Nonresponsive.
gels.swell.when.exposed.to.water,.whereas.responsive.gels.are.formed.when.exposed.to.
other.stimuli.including.temperature,.pH,.and.light.(Luchini.et.al..2008)..Since.hydrogels.
