Biomedical Engineering Reference
In-Depth Information
Cm-loaded
nanofibers
Unmodified
fibers
Cm control
(in PBS)
Figure 28.2
(See companion CD for color igure.)
.Chloramphenicol.(Cm)-loaded.polylactic.co-glycolic.acid.(PLGA).nano-
ibers. were. tested. against.
Bacillus cereus
. using. a. zone. of. clearing. test.. Both. the. Cm-loaded. nanoibers. and. a.
control.spot.containing.Cm.alone.were.effective.inhibitors.of.bacterial.growth..Unmodiied.PLGA.nanoibers.
had.no.visible.effect.on.bacterial.growth.
used. as. comparative. controls. (Sondi. and. Salopek-Sondi. 2004,. Kim. et. al.. 2007,. Choi. et. al..
2008).. Silver. is. by. far. the. most. commonly. used. inorganic. material. (including. nanomate-
rial).used.in.antimicrobial.consumer.products.(Rejeski.2009)..Other.inorganic.antimicrobial.
nanomaterials.and.their.composites.have.been.identiied.including.titanium.dioxide.(TiO
2
;.
Fu.et.al..2005),.zinc.oxide.(ZnO),.copper.and.its.oxides.(CuO.and.Cu
2
O;.Kasemets.et.al..2009),.
metal-carbon.nanotube.composites.(Kang.et.al..2007),.and.nanoclays.(Wilson.2003)..With.
silver.and.similar.metal/metal-oxide-based.nanomaterial.agents,.the.general.mechanism.
of.action.is.largely.unknown;.however,.enhanced.metal-ion.release,.and.speciic.action.at.
the.organism-nanomaterial.interface.(e.g.,.reactive.oxide.species).and.combinations.thereof.
have.been.studied.(Marambio-Jones.and.Hoek.2010)..The.antimicrobial.properties.of.cer-
tain.metals.have.been.known.for.centuries,.and.unlike.traditional.antibiotic.drugs,.there.are.
little.data.to.suggest.that.bacterial.pathogens.(for.example).have.effective.active.or.adaptive.
mechanisms.for.developing.metal.tolerance.or.resistance..This.is.also.true.for.metal-based.
nanomaterials.that.exhibit.an.apparent.enhanced.antimicrobial.property.from.bulk.met-
als.(and.even.metal.ions).due.to.a.marked.increase.in.surface.area-to-volume.ratio—a.key.
differential.when.considering.the.enhancement.in.catalytic.activities.that.typically.occurs.
at.nanoparticle.surfaces..This.last.point.is.important.considering.the.unique.challenge.in.
nanoscience.of.protecting.the.surface.of.nanomaterials.to.prevent.or.control.their.tendency.
to.aggregate.into.larger.bodies.(often.rendering.them.ineffective)..Controlling.the.surface.
chemistry.of.nanomaterials.is.also.important.for.controlling.their.environmental.fate,.and.
anchoring.these.materials.to.solid.supports.is.an.effective.approach.
28.3 Rational Design to Control Exposure and Environmental Release
One.of.the.goals.of.our.research.has.been.to.develop.model.metal.nanoparticle.composite.
materials. using. a. simple,. scalable,. highly. controlled. deposition. process.. Our. focus. is. to.
