244
Bacterial Cellulose
Insulating. fibrous. polymer. membranes. can. be. obtained. through. many.
techniques,.such.as.phase.separation.(Fu.et.al..2005),.drawing.(Williamson.
and.Coombes.2004),.template.synthesis.(Lu.et.al..2005),.self-assembly.(Kweon.
et. al.. 2003),. and. electrospinning. (MacDiarmid. 2001a,. 2001b;. MacDiarmid.
et al.. 2001;. Picciani. et. al.. 2009;. Wei. et. al.. 2005).. Among. these,. electrospinning. has. been. the. most. easily. adopted. technique. to. produce. conductive. nanofibrous. membranes. due. to. its. versatility,. relatively. low. cost,. and.
simplicity. of. production.. Conductive. nanofibrous. films. obtained. through.
electro. spinning. can. be. divided. basically. into. two. categories:. (1). those.
obtained.by.a.direct.method,.in.which.conducting.and.insulating.polymers.
are.previously.blended.in.a.solution.and.then.electrospun.to.create.a.conductive.nanofibrous.membrane—the.main.disadvantage.of.this.approach.lies.in.
the.difficulty.in.producing.a.stable.and.homogeneous.conductive.polymer.
solution—and. (2). those. obtained. by. a. two-step. technique. in. which. previously. electrospun. membranes. are. coated. with. polyaniline. or. polypyrrole.
by.in.situ.polymerization..Conductive.nanofibrous.membranes.of.polyaniline.or.polypyrrole.and.insulating.polymers.have.been.fabricated.through.
electrospinning. polymer. mixture. solutions. by. tailoring. the. conducting.
and.insulating.polymer.concentrations,.in.combination.with.the.use.of.several.solvents,.including.water..Poly(ethylene.oxide).(PEO),.polyacrylonitrile.
(PAN),.polystyrene.(PS),.poly(L-lactic.acid).(PLA),.poly(methyl.methacrylate).
(PMMA),. polycarbonate. (PC),. polystyrene/polybutadiene. (PS/PB). (75:25),.
and. poly(ε-caprolactone)/gelatin. (PCL/PG). (70:30). are. among. the. most.
representative.examples.of.insulating.polymers.used.in.the.preparation.of.
conductive. nanofibers. (MacDiarmid. 2001a,. 2001b;. MacDiarmid. et. al.. 2001;.
Picciani.et.al..2009;.Wei.et.al..2005).
Several.reports.have.demonstrated.the.potential.of.polyaniline.and.polypyrrole.for.the.production.of.conductive.porous.nanofibrous.blends.as.scaffolds.
to. improve. nerve. cell. attachment. and. proliferation. (Ghasemi-Mobarakeh.
et al.. 2009,. 2011;. Gizdavic-Nikolaidis. et. al.. 2010;. Lee. et al.. 2009;. Xie. et. al..
2009).. Recently. Ghasemi-Mobarakeh. et. al.. (2009). reported. the. preparation.
of. conductive. scaffolds. based. on. PCL/PG. and. doped. PAni. through. an.
electro. spinning. process.. The. prepared. scaffolds. were. used. to. electrically.
stimulate. nerve. cells,. resulting. in. a. substantial. increase. in. cell. proliferation.and.neurite.outgrowth.as.compared.to.a.control.using.nonstimulated.
nanofibrous. templates.. Li. et. al.. (2006). prepared. (in. vivo). biocompatible.
fibrous. scaffolds. comprised. of. PAni/cross-linked. gelatin. endowed. with.
an.electrical.conductivity.of.0.01.S/cm;.this.nanostructured.composite.was.
also.shown.to.support.in.vitro.the.growth.and.proliferation.of.H9c2.cardiac.
myoblasts..Conductive.membranes.of.poly(aniline-co-3-aminobenzoic.acid).
. copolymer.and.PLA.fabricated.through.electrospinning.using.a.range.of.relative.proportions.of.both.components.have.also.been.demonstrated.to.have.
good. biocompatibility. .. These. blends. did. not. allow. enhanced. in. vitro. cell.
growth,. but. displayed. antimicrobial. capacity. against. Staphylococcus aureus.
(Gizdavic-Nikolaidis.et al. 2010).
Bacterial Cellulose
Insulating. fibrous. polymer. membranes. can. be. obtained. through. many.
techniques,.such.as.phase.separation.(Fu.et.al..2005),.drawing.(Williamson.
and.Coombes.2004),.template.synthesis.(Lu.et.al..2005),.self-assembly.(Kweon.
et. al.. 2003),. and. electrospinning. (MacDiarmid. 2001a,. 2001b;. MacDiarmid.
et al.. 2001;. Picciani. et. al.. 2009;. Wei. et. al.. 2005).. Among. these,. electrospinning. has. been. the. most. easily. adopted. technique. to. produce. conductive. nanofibrous. membranes. due. to. its. versatility,. relatively. low. cost,. and.
simplicity. of. production.. Conductive. nanofibrous. films. obtained. through.
electro. spinning. can. be. divided. basically. into. two. categories:. (1). those.
obtained.by.a.direct.method,.in.which.conducting.and.insulating.polymers.
are.previously.blended.in.a.solution.and.then.electrospun.to.create.a.conductive.nanofibrous.membrane—the.main.disadvantage.of.this.approach.lies.in.
the.difficulty.in.producing.a.stable.and.homogeneous.conductive.polymer.
solution—and. (2). those. obtained. by. a. two-step. technique. in. which. previously. electrospun. membranes. are. coated. with. polyaniline. or. polypyrrole.
by.in.situ.polymerization..Conductive.nanofibrous.membranes.of.polyaniline.or.polypyrrole.and.insulating.polymers.have.been.fabricated.through.
electrospinning. polymer. mixture. solutions. by. tailoring. the. conducting.
and.insulating.polymer.concentrations,.in.combination.with.the.use.of.several.solvents,.including.water..Poly(ethylene.oxide).(PEO),.polyacrylonitrile.
(PAN),.polystyrene.(PS),.poly(L-lactic.acid).(PLA),.poly(methyl.methacrylate).
(PMMA),. polycarbonate. (PC),. polystyrene/polybutadiene. (PS/PB). (75:25),.
and. poly(ε-caprolactone)/gelatin. (PCL/PG). (70:30). are. among. the. most.
representative.examples.of.insulating.polymers.used.in.the.preparation.of.
conductive. nanofibers. (MacDiarmid. 2001a,. 2001b;. MacDiarmid. et. al.. 2001;.
Picciani.et.al..2009;.Wei.et.al..2005).
Several.reports.have.demonstrated.the.potential.of.polyaniline.and.polypyrrole.for.the.production.of.conductive.porous.nanofibrous.blends.as.scaffolds.
to. improve. nerve. cell. attachment. and. proliferation. (Ghasemi-Mobarakeh.
et al.. 2009,. 2011;. Gizdavic-Nikolaidis. et. al.. 2010;. Lee. et al.. 2009;. Xie. et. al..
2009).. Recently. Ghasemi-Mobarakeh. et. al.. (2009). reported. the. preparation.
of. conductive. scaffolds. based. on. PCL/PG. and. doped. PAni. through. an.
electro. spinning. process.. The. prepared. scaffolds. were. used. to. electrically.
stimulate. nerve. cells,. resulting. in. a. substantial. increase. in. cell. proliferation.and.neurite.outgrowth.as.compared.to.a.control.using.nonstimulated.
nanofibrous. templates.. Li. et. al.. (2006). prepared. (in. vivo). biocompatible.
fibrous. scaffolds. comprised. of. PAni/cross-linked. gelatin. endowed. with.
an.electrical.conductivity.of.0.01.S/cm;.this.nanostructured.composite.was.
also.shown.to.support.in.vitro.the.growth.and.proliferation.of.H9c2.cardiac.
myoblasts..Conductive.membranes.of.poly(aniline-co-3-aminobenzoic.acid).
. copolymer.and.PLA.fabricated.through.electrospinning.using.a.range.of.relative.proportions.of.both.components.have.also.been.demonstrated.to.have.
good. biocompatibility. .. These. blends. did. not. allow. enhanced. in. vitro. cell.
growth,. but. displayed. antimicrobial. capacity. against. Staphylococcus aureus.
(Gizdavic-Nikolaidis.et al. 2010).