166
Bacterial Cellulose
were. freeze-dried. for. 24. h. and. then. analyzed. for. swelling. ratio. and. antibacterial.activity.against.strains.of.E. coli,.S. aureus,.and.Bacillus subtilis..They.
were.found.to.absorb.at.least.26.2.and.37.3.times.their.own.weight.of.water.
and. saline,. respectively,. within. 24. h.. Drug. upload. capacities. ranged. from.
0.0291.to.0.145.mg/cm 2 .and.stable.antimicrobial.effect.was.observed.against.
Gram-positive.bacteria.(S. aureus.and.B. subtilis).for.at.least.24.h.
Described. in. U.S.. Patent. 7,704,523. (Table 8.3),. microbial. cellulose. wound.
dressings. containing. 2700. ppm. of. PHMB. displayed. antimicrobial. activity.
against.bacteria.like.E. coli.and.S..aureus.and.fungi.like.Aspergillus niger and.
Candida albicans..PHMB.is.a.disinfectant.commonly.used.in.hospitals,.with.
a. broad. spectrum. of. activities. against. Gram-negative. and. Gram-positive.
bacteria,.fungi,.and.protozoa..It.ionically.binds.to.cellulose.nanofibers..The.
resulting.dressings.are.effective.in.the.treatment.of.chronic.wounds.that.are.
particularly.prone.to.microbial.infections.
Good.antibacterial.and.barrier.properties.as.well.as.high.mechanical.durability. and. moisture. retention. were. achieved. when. bacterial. cellulose. was.
modified.with.chitosan.(Gupta.et.al..2010)..The.obtained.composite.material.
activity,.biocompatibility,.and.biodegradability..It.was.applicable.in.the.management. of. burns,. bedsores,. skin. ulcers,. and. other. chronic. wounds,. and.
accelerated.wound.healing.without.any.symptoms.of.irritation.or.allergy.
Another.method.of.manufacturing.BNC.dressings.with.bactericidal.activity. is. proposed. in. PL. Patent. application. 392,480. (Table 8.3).. The. purified.
BNC.membranes.are.oxidized.with.sodium.periodate.to.generate.aldehyde.
groups.between.C2.and.C3.of.glucose.residues.that.enable.covalent.binding.
of.lysozyme,.which.degrades.bacterial.cell.wall.peptidoglycan.
A.potential.method.of.modification.of.bacterial.cellulose.wound.dressings,.
making.them.resistant.to.microbial.adhesion,.consists.of.covalent.immobilization.of.antimicrobial.peptides.(Costa.et.al..2011)..Such.peptides.were.linked.
to.many.polymers,.including.plant.cellulose.
BNC Dressings with Antioxidant and Protease-Binding Activities
As.was.mentioned.earlier,.bacterial.cellulose.has.no.impact.on.the.activity.of.
proteolytic. enzymes,. which. are. particularly. high. in. exudates. from. chronic.
wounds.such.as.venous,.pressure,.and.diabetic.ulcers.(Wiegand.et.al..2006)..
Such. wounds. persist. in. the. inflammatory. state. and. fail. to. heal. because. of.
elevated. activity. of. destructive. proteases,. proinflammatory. cytokines,. and.
reactive.oxygen.species..One.of.the.methods.used.in.the.treatment.of.such.
chronic. wounds. is. the. application. of. dressings. containing. collagen. fibrils,.
which.display.antioxidant.activity.and.decrease.the.activity.of.enzymes.such.
as.elastase.from.polymorphonuclear.granulocytes.(PMN.elastase).and.matrix.
metalloproteases.(MMPs).produced.by.macrophages..The.first.enzyme.participates.in.wound.debridement.and.combating.microbial.infections,.. however,.
its.elevated.activity.is.harmful.to.healthy.tissue.surrounding.the.wound.
Bacterial Cellulose
were. freeze-dried. for. 24. h. and. then. analyzed. for. swelling. ratio. and. antibacterial.activity.against.strains.of.E. coli,.S. aureus,.and.Bacillus subtilis..They.
were.found.to.absorb.at.least.26.2.and.37.3.times.their.own.weight.of.water.
and. saline,. respectively,. within. 24. h.. Drug. upload. capacities. ranged. from.
0.0291.to.0.145.mg/cm 2 .and.stable.antimicrobial.effect.was.observed.against.
Gram-positive.bacteria.(S. aureus.and.B. subtilis).for.at.least.24.h.
Described. in. U.S.. Patent. 7,704,523. (Table 8.3),. microbial. cellulose. wound.
dressings. containing. 2700. ppm. of. PHMB. displayed. antimicrobial. activity.
against.bacteria.like.E. coli.and.S..aureus.and.fungi.like.Aspergillus niger and.
Candida albicans..PHMB.is.a.disinfectant.commonly.used.in.hospitals,.with.
a. broad. spectrum. of. activities. against. Gram-negative. and. Gram-positive.
bacteria,.fungi,.and.protozoa..It.ionically.binds.to.cellulose.nanofibers..The.
resulting.dressings.are.effective.in.the.treatment.of.chronic.wounds.that.are.
particularly.prone.to.microbial.infections.
Good.antibacterial.and.barrier.properties.as.well.as.high.mechanical.durability. and. moisture. retention. were. achieved. when. bacterial. cellulose. was.
modified.with.chitosan.(Gupta.et.al..2010)..The.obtained.composite.material.
activity,.biocompatibility,.and.biodegradability..It.was.applicable.in.the.management. of. burns,. bedsores,. skin. ulcers,. and. other. chronic. wounds,. and.
accelerated.wound.healing.without.any.symptoms.of.irritation.or.allergy.
Another.method.of.manufacturing.BNC.dressings.with.bactericidal.activity. is. proposed. in. PL. Patent. application. 392,480. (Table 8.3).. The. purified.
BNC.membranes.are.oxidized.with.sodium.periodate.to.generate.aldehyde.
groups.between.C2.and.C3.of.glucose.residues.that.enable.covalent.binding.
of.lysozyme,.which.degrades.bacterial.cell.wall.peptidoglycan.
A.potential.method.of.modification.of.bacterial.cellulose.wound.dressings,.
making.them.resistant.to.microbial.adhesion,.consists.of.covalent.immobilization.of.antimicrobial.peptides.(Costa.et.al..2011)..Such.peptides.were.linked.
to.many.polymers,.including.plant.cellulose.
BNC Dressings with Antioxidant and Protease-Binding Activities
As.was.mentioned.earlier,.bacterial.cellulose.has.no.impact.on.the.activity.of.
proteolytic. enzymes,. which. are. particularly. high. in. exudates. from. chronic.
wounds.such.as.venous,.pressure,.and.diabetic.ulcers.(Wiegand.et.al..2006)..
Such. wounds. persist. in. the. inflammatory. state. and. fail. to. heal. because. of.
elevated. activity. of. destructive. proteases,. proinflammatory. cytokines,. and.
reactive.oxygen.species..One.of.the.methods.used.in.the.treatment.of.such.
chronic. wounds. is. the. application. of. dressings. containing. collagen. fibrils,.
which.display.antioxidant.activity.and.decrease.the.activity.of.enzymes.such.
as.elastase.from.polymorphonuclear.granulocytes.(PMN.elastase).and.matrix.
metalloproteases.(MMPs).produced.by.macrophages..The.first.enzyme.participates.in.wound.debridement.and.combating.microbial.infections,.. however,.
its.elevated.activity.is.harmful.to.healthy.tissue.surrounding.the.wound.