Figure 6.10
129
Nematic Ordered Cellulose Templates
The.ordered.amphiphilic.tracks.of.hydrophilic.OH.groups.and.hydro. phobic.
polarity.in.NOC.can.induce.an.epitaxial.deposition.of.biosynthesized.cellulose.nanofibers.secreted.from.the.Gram-negative.bacterium,.G. xylinus,.along.
the.same.axis.of.the.tracks.in.NOC.(Kondo.et.al..2002)..When.active.G. xylinus.
cells.are.transferred.to.the.oriented.surface,.they.synthesize.. cellulose.nanofibers.parallel.to.the.molecular.orientation.of.the.substrate..This.is.evidenced.
by.direct.video.imaging.of.the.motion.of.the.bacteria.as.they.synthesize.the.
synthesis.was.reported.in.1976.by.Brown.et.al..The.cell.movement.(at.a.constant.rate.of.4.5.μm/min.at.24°C).is.the.result.of.an.inverse.force.imposed.by.
the.directed.polymerization.and.crystallization.of.the.cellulose..It.is.also.well.
known.that.the.bacterium.rotates.on.its.own.axis..The.biodirected.epitaxial.
nanodeposition. of. secreted. fibers. was. studied. over. time. and. under. varied.
conditions,.including.different.substrates..Typically.a.time.course.analysis.of.
an.NOC.template.shows.a.bacterium.moving.in.contact.with.a.stretched.NOC.
substrate,.as.shown.in.Figure 6.10..Basically.the.cells.on.the.NOC.template.
move.straight.along.the.molecular.tracks..Midway.through.this.series.the.cell.
“jumps. off”. of. the. oriented. substrate. and. continues. to. secrete. its. . cellulose.
nanofiber,.but.now.in.the.form.of.a.spiral.or.tunnel.structure.that.is.the.normal.pattern.of.formation.when.not.in.contact.with.any.organized.substrate.
(Thompson. et al.. 1988).. When. the. interaction. between. the. bacterium. and.
25 µm
Bacterium
Time course
NOC orientation
1
2
3
4
5
Typical bacterial movement on NOC
6
Fiber
Figure 6.10
Successive.images.showing.the.motion.of.a.bacterium.as.it.secretes.a.cellulose.ribbon.using.
real-time.video.analysis..In.(1),.the.bacterium.is.attached.to.and.synthesizing.its.cellulose.on.
the.monomolecular.rail.track..In.(2),.the.bacterium.has.jumped.the.track.and.is.beginning.to.
change. its. orientation.. In. (3–5),. the. bacterium. is. generating. the. first. complete. spiral.. In. (6),.
the bacterium.is.on.the.second.rotation.of.a.spiral.
129
Nematic Ordered Cellulose Templates
The.ordered.amphiphilic.tracks.of.hydrophilic.OH.groups.and.hydro. phobic.
polarity.in.NOC.can.induce.an.epitaxial.deposition.of.biosynthesized.cellulose.nanofibers.secreted.from.the.Gram-negative.bacterium,.G. xylinus,.along.
the.same.axis.of.the.tracks.in.NOC.(Kondo.et.al..2002)..When.active.G. xylinus.
cells.are.transferred.to.the.oriented.surface,.they.synthesize.. cellulose.nanofibers.parallel.to.the.molecular.orientation.of.the.substrate..This.is.evidenced.
by.direct.video.imaging.of.the.motion.of.the.bacteria.as.they.synthesize.the.
synthesis.was.reported.in.1976.by.Brown.et.al..The.cell.movement.(at.a.constant.rate.of.4.5.μm/min.at.24°C).is.the.result.of.an.inverse.force.imposed.by.
the.directed.polymerization.and.crystallization.of.the.cellulose..It.is.also.well.
known.that.the.bacterium.rotates.on.its.own.axis..The.biodirected.epitaxial.
nanodeposition. of. secreted. fibers. was. studied. over. time. and. under. varied.
conditions,.including.different.substrates..Typically.a.time.course.analysis.of.
an.NOC.template.shows.a.bacterium.moving.in.contact.with.a.stretched.NOC.
substrate,.as.shown.in.Figure 6.10..Basically.the.cells.on.the.NOC.template.
move.straight.along.the.molecular.tracks..Midway.through.this.series.the.cell.
“jumps. off”. of. the. oriented. substrate. and. continues. to. secrete. its. . cellulose.
nanofiber,.but.now.in.the.form.of.a.spiral.or.tunnel.structure.that.is.the.normal.pattern.of.formation.when.not.in.contact.with.any.organized.substrate.
(Thompson. et al.. 1988).. When. the. interaction. between. the. bacterium. and.
25 µm
Bacterium
Time course
NOC orientation
1
2
3
4
5
Typical bacterial movement on NOC
6
Fiber
Figure 6.10
Successive.images.showing.the.motion.of.a.bacterium.as.it.secretes.a.cellulose.ribbon.using.
real-time.video.analysis..In.(1),.the.bacterium.is.attached.to.and.synthesizing.its.cellulose.on.
the.monomolecular.rail.track..In.(2),.the.bacterium.has.jumped.the.track.and.is.beginning.to.
change. its. orientation.. In. (3–5),. the. bacterium. is. generating. the. first. complete. spiral.. In. (6),.
the bacterium.is.on.the.second.rotation.of.a.spiral.