Biomedical Engineering Reference
In-Depth Information
The.antibacterial.activities.of.the.CuO-fabric.composite.were.tested.against.
E.coli
.(Gram-
negative).and.
S. aureus
.(Gram-positive).cultures..These.coated.fabrics.can.have.potential.
applications.in.wound.dressing,.bed.linens,.and.as.active.bandages.
18.3 NaturalAntimicrobialAgents
18.3.1 Chitosan Coated on Cotton Fabric
Textile.goods,.especially.those.made.from.natural.ibers,.are.often.considered.to.be.more.
vulnerable. to. microbial. attack. than. man-made. ibers. because. of. their. large. surface. area.
and.ability.to.retain.moisture..Therefore,.the.use.of.antibacterial.agents.to.prevent.or.retard.
the.growth.of.bacteria.is.becoming.a.standard.inishing.for.textile.goods;.unfortunately,.
many.antibacterial.agents.are.toxic.chemicals.
46
.Thus,.an.ideal.textile.antimicrobial.inish-
ing.should.be.safe.and.environmentally.benign,.in.addition.to.killing.undesirable.microor-
ganisms.
47
.Chitosan,.a.natural.biopolymer,.has.a.combination.of.many.unique.properties,.
such.as.biodegradablility,.nontoxicity,.cationic.nature,.and.antibacterial.activity.
48
.Because.
of.its.polycationic.nature,.chitosan.possesses.good.antimicrobial.properties.against.various.
bacteria.and.fungi.through.ionic.interaction.at.the.cell.surface,.which.eventually.kills.the.
bacterial. cells.
48
.Direct.coating.of.chitosan.on. cotton.fabric. was. invented. to.enhance.the.
water. solubility. of. chitosan. over. the. entire. pH. range. using. the. quaternary. ammonium.
salt,.
O
-acrylamidomethyl-
N
-[(2-hydroxy-3. trimetylammonium)propyl]. chitosan. chloride.
(NMA-HTCC).
49
.The.cotton.treated.with.NMA-HTCC.by.the.cold-pad.batch.method.in.the.
presence.of.an.alkaline.catalyst.at.a.concentration.of.1%.on.weight.of.fabric.showed.100%.
S. aureus
.reduction..The.effectiveness.was.maintained.over.99%.even.after.being.exposed.
to.50.consecutive.home.laundering.washes..Another.improvement.to.chitosan.coating.on.
cotton.fabric.employed.chitosan-based.core-shell.particles,.with.chitosan.as.the.shell.and.
a.soft.polymer.as.the.core.
50
.The.core-shell.particles.were.synthesized.via.a.graft.copoly-
merization.of.
n
-butyl.acrylate.(PBA).from.chitosan.in.aqueous.solution..The.cotton.fabric.
coated.with.these.PBA-chitosan.particles.using.the.pad-dry-cure.method.showed.excellent.
antibacterial.activity,.with.more.than.99%.reduction.of.
S. aureus
.
When.Holappa.and.co-workers
51
.studied.the.effect.of.the.degree.of.substitution.on.the.
antimicrobial. activity. of. water-soluble. quaternary. chitosan.
N
-betainates. against.
E. coli
.
and.
S. aureus
,.they.found.that.the.antimicrobial.activity.increased.with.decreasing.degrees.
of.substitution.in.acidic.conditions.(pH.5.5)..In.a.similar.investigation.by.Alonso.and.co-
workers,
52
.it.was.found.that.the.use.of.citric.acid.as.the.cross-linking.agent.and.NaH
2
PO
4
.
as.the.catalyst.over.a.previously.UV-irradiated.raw.cotton.sample.gave.the.highest.chitosan.
incorporation.of.27.mg/g.of.functionalized.textile..The.control.against.growth.of.
P. chry-
sogenum
.and.
E. coli
.directly.related.to.the.amount.of.chitosan.incorporated.into.the.iber.
Nanochitosan. is. a. natural. material. with. excellent. physicochemical. properties.. It. has.
been.used.to.improve.the.strength.and.washability.of.textiles.and.to.confer.antibacterial.
effects.
53
.Nanochitosan.(NCH).was.prepared.from.low.molecular.weight.chitosan.(LMCS).
by. Yang. and. co-workers.
54
. The. wool. fabric. was. treated. with. various. types. of. chitosan..
The.antibacterial.and.shrink-prooing.properties.of.the.treated.fabric.were.ranked.as.fol-
lows:.NCH.>.LMCS.>.chitosan..The.properties.also.increased.as.the.concentration.of.NCH.
increased..In.addition,.the.nanochitosan-treated.wool.fabric.possessed.better.antibacterial.
and.shrink-prooing.properties.after.washing.for.20.times.
