100
Bacterial Cellulose
degrade. rapidly. in. water,. phosphate-buffered. saline. (PBS),. and. simulated.
body.fluids..In.another.study,.Hutchens.et.al..(2009).demonstrated.that.periodate.oxidized.BNC.retains.its.original.structure.and.ability.to.initiate.the.
mineralization.of.calcium-deficient.hydroxyapatite,.similar.to.natural.bone.
apatite..These.studies.suggest.that.the.improved.biodegradability.provided.
by. periodate. oxidization. of. BNC. can. increase. its. potential. applications. in.
tissue.engineering.
Incorporation of Antimicrobial Agents
For. some. biomedical. applications. and. in. the. food. industry,. where. BC. is.
widely. used,. control. of. microorganisms. is. of. great. importance.. Although.
BNC.itself.has.no.antimicrobial.activity,.its.structure.allows.the.incorporation.
of.antimicrobial.agents,.which.may.vary.according.to.the.final.application.
Mainly.due.to.its.ability.to.maintain.a.moist.environment.within.wounds,.
significantly. reduce. pain,. accelerate. reepithelialization. and. formation. of.
granulation.tissue,.and.reduce.scar.formation,.BNC.is.considered.an.effective.
wound.dressing.material.(Czaja.et.al..2006)..In.fact,.BNC-based.commercial.
products,.such.as.BioFill ® .(BioFill.Produtos.Biotecnológicos,.Brazil),.Bionext ® .
(Bionext.Produtos.Biotecnológicos,.Brazil),.and.XCell ® .(Xylos.Corporation,.PA,.
USA).have.been.shown.to.effectively.accelerate.the.wound.healing.process.
(Alvarez.et.al..2004;.Fontana.et.al..1990;.Osman.et.al..2007)..Maneerung.et al..
(2008). used. silver. nanoparticles. to. achieve. antimicrobial. activity. in. BNC.
membranes.for.wound.healing.applications,.thus.preventing.wound.infection..For.this.purpose,.BNC.was.immersed.in.a.silver.nitrate.solution,.then.
sodium.borohydride.was.used.to.reduce.the.absorbed.silver.ion.(Ag + ).inside.
the. BNC. network. to. metallic. silver. nanoparticles. (Ag 0 ).. Results. obtained.
showed.that.the.freeze-dried.silver.nanoparticle-impregnated.BC.exhibited.
strong. antimicrobial. activity. against. Escherichia coli. (Gram. negative). and.
Staphylococcus aureus (Gram.positive),.bacteria.commonly.found.in.infected.
wounds.. In. fact,. the. unique. structure. and. high. oxygen. density. (ether. and.
hydroxyl. groups). of. BNC. fibers. was. shown. to. be. an. effective. nanoreactor.
for.in.situ.synthesis.of.silver.nanoparticles..These.properties.are.essential.for.
the.introduction.of.silver.ions.since.they.allow.the.tight.anchoring.of.these.
ions.onto.BNC.fibers.via.ion-dipole.interactions,.as.well.as.they.help.stabilize.
silver.nanoparticles.by.strong.interactions.with.their.surface.metal.atoms.
In.2009.Cai.et.al..developed.a.BC-chitosan.blend.by.immersing.wet.BNC.
pellicles. in. a. chitosan. solution,. followed. by. freeze-drying.. The. final. product. presented. a. foamy. structure. with. an. interconnected. porous. network..
Incorporation.of.chitosan. did. not.affect.the.BNC.structure,.although. crystallinity. decreased. from. 82%. to. 61%. as. chitosan. content. increased. from.
12%. to. 41%,. and. thermal. stability. was. improved.. Moreover,. the. authors.
Bacterial Cellulose
degrade. rapidly. in. water,. phosphate-buffered. saline. (PBS),. and. simulated.
body.fluids..In.another.study,.Hutchens.et.al..(2009).demonstrated.that.periodate.oxidized.BNC.retains.its.original.structure.and.ability.to.initiate.the.
mineralization.of.calcium-deficient.hydroxyapatite,.similar.to.natural.bone.
apatite..These.studies.suggest.that.the.improved.biodegradability.provided.
by. periodate. oxidization. of. BNC. can. increase. its. potential. applications. in.
tissue.engineering.
Incorporation of Antimicrobial Agents
For. some. biomedical. applications. and. in. the. food. industry,. where. BC. is.
widely. used,. control. of. microorganisms. is. of. great. importance.. Although.
BNC.itself.has.no.antimicrobial.activity,.its.structure.allows.the.incorporation.
of.antimicrobial.agents,.which.may.vary.according.to.the.final.application.
Mainly.due.to.its.ability.to.maintain.a.moist.environment.within.wounds,.
significantly. reduce. pain,. accelerate. reepithelialization. and. formation. of.
granulation.tissue,.and.reduce.scar.formation,.BNC.is.considered.an.effective.
wound.dressing.material.(Czaja.et.al..2006)..In.fact,.BNC-based.commercial.
products,.such.as.BioFill ® .(BioFill.Produtos.Biotecnológicos,.Brazil),.Bionext ® .
(Bionext.Produtos.Biotecnológicos,.Brazil),.and.XCell ® .(Xylos.Corporation,.PA,.
USA).have.been.shown.to.effectively.accelerate.the.wound.healing.process.
(Alvarez.et.al..2004;.Fontana.et.al..1990;.Osman.et.al..2007)..Maneerung.et al..
(2008). used. silver. nanoparticles. to. achieve. antimicrobial. activity. in. BNC.
membranes.for.wound.healing.applications,.thus.preventing.wound.infection..For.this.purpose,.BNC.was.immersed.in.a.silver.nitrate.solution,.then.
sodium.borohydride.was.used.to.reduce.the.absorbed.silver.ion.(Ag + ).inside.
the. BNC. network. to. metallic. silver. nanoparticles. (Ag 0 ).. Results. obtained.
showed.that.the.freeze-dried.silver.nanoparticle-impregnated.BC.exhibited.
strong. antimicrobial. activity. against. Escherichia coli. (Gram. negative). and.
Staphylococcus aureus (Gram.positive),.bacteria.commonly.found.in.infected.
wounds.. In. fact,. the. unique. structure. and. high. oxygen. density. (ether. and.
hydroxyl. groups). of. BNC. fibers. was. shown. to. be. an. effective. nanoreactor.
for.in.situ.synthesis.of.silver.nanoparticles..These.properties.are.essential.for.
the.introduction.of.silver.ions.since.they.allow.the.tight.anchoring.of.these.
ions.onto.BNC.fibers.via.ion-dipole.interactions,.as.well.as.they.help.stabilize.
silver.nanoparticles.by.strong.interactions.with.their.surface.metal.atoms.
In.2009.Cai.et.al..developed.a.BC-chitosan.blend.by.immersing.wet.BNC.
pellicles. in. a. chitosan. solution,. followed. by. freeze-drying.. The. final. product. presented. a. foamy. structure. with. an. interconnected. porous. network..
Incorporation.of.chitosan. did. not.affect.the.BNC.structure,.although. crystallinity. decreased. from. 82%. to. 61%. as. chitosan. content. increased. from.
12%. to. 41%,. and. thermal. stability. was. improved.. Moreover,. the. authors.