101
Bacterial Cellulose Surface Modifications
demonstrated. that. the. mechanical. and. antibacterial. properties. of. the.
BNC-chitosan.pellicle.were.appropriate.for.biomedical.applications,.such.as.
tissue.engineering.scaffold.and.wound.dressing.material.
More.recently,.a.new,.functional,.dry.BNC.film.containing.benzalkonium.
chloride.was.developed.by.Wei.et.al..(2011)..Benzalkonium.chloride.is.an.antimicrobial. cationic. surfactant. widely. used. in. commercial. wound. dressings,.
especially. effective. against. Gram-positive. bacteria.. The. antimicrobial. BNC.
konium.chloride.solution.for.24.h,.followed.by.removal.of.nonabsorbed.antimicrobial.agent.and.another.24.h.of.freeze-drying..The.final.dry.BNC.film.
possessed.good.portability,.high.water.absorption.capability,.and.strong.antibacterial.properties,.being.able.to.sustain.a.stable.and.lasting.release.of.the.
antimicrobial.agent.for.at.least.24.h.(Figure 5.5)..Therefore.there.is.potential.
for.these.films.as.a.commercial.product.for.the.treatment.of.acute.traumas.
Bacterial. nanocellulose. has. also. attracted. interest. in. the. food. industry.
as. a. material. for. active. packaging,. which. is. defined. as. packaging. able. to.
perform.roles.other.than.that.of.a.barrier.to.the.outside.environment..This.
is.mostly.due.to.BNC’s.edibility.and.potential.as.a.good.carrier.for.a.wide.
range. of. antimicrobial. agents. (Cagri. et. al.. 2004).. This. potential. has. been.
exploited.by.Nguyen.et.al..(2008),.who.developed.BNC.films.incorporating.
nisin.as.a.proof-of-concept.study.to.control.Listeria monocytogenes.and.total.
aerobic. bacteria. on. the. surface. of. vacuum-packaged. frankfurters.. For. that.
purpose,.BNC.films.were.soaked.in.a.nisin.solution.under.static.conditions,.
followed.by.drying.at.50°C..Nisin-containing.BNC.films.showed.effectiveness.in.controlling.L. monocytogenes.and.reducing.total.plate.counts.on.the.
surface.of.frankfurters,.thus.opening.interesting.prospects.as.a.new.method.
to.improve.the.safety.and.extend.the.shelf.life.of.processed.meats.
Enzyme Immobilization
Immobilization.of.biologically.active.proteins.is.of.great.relevance.in.different.fields,.from.the.food.industry.to.biomedical.engineering.and.biosensors,.
among. others. (Shpigel. et. al.. 1999).. Enzymes,. in. particular,. may. be. immobilized. by. adsorption. or. covalent. bonding. to. solid. matrices,. as. well. as. by.
entrapment.or.encapsulation.in.polymeric.substances..Immobilization.allows.
the. improvement. of. enzyme. stability. under. specific. process. conditions.
(Wu and Lia.2008).
Cellulose.is.an.attractive.matrix.for.enzyme.immobilization.because.of.its.
highly.suitable.physical.properties.and.low.cost..Therefore.cellulose-binding.
domains. (CBDs). constitute. an. excellent. tool. to. immobilize. proteins. on.
. cellulose,. as. previously. demonstrated. by. Shpigel. et. al.. (1999),. by. fusing.
. heparinase.I.to.CBDs.