TABLe 9.1
Selected.Material.Characteristics.of.the.Different.BNC.Samples.(Wesarg.et.al..2010)
DSM 14666
ATCC 53582
ATCC 10245
ATCC 23769
Degree.of.polymerization
2761
1966
920
775
Crystallinity.(%)
90
88
86
84
Tensile.strength.(MPa)
0.340.±.0.020
0.314.±.0.009
0.184.±.0.028
0.035.±.0.009
Compressive.stress.(MPa)
2.658.±.0.092
2.408.±.0.067
0.434.±.0.102
0.029.±.0.002
Water.retention.value.(%)
642
626
235
250
Storage.modulus.(G′).(Pa)
30,926.±.858
26,286.±.2898
15,282.±.1701
1495.±.355
Bacterial Nanocellulose Hydrogels Designed as Bioartificial Medical Implants 185
pivotal.to.exactly.determine.the.relative.importance.of.the.different.experimental.factors.on.the.structure.and.properties.of.BNC..This.concerns.both.
the.reproducibility.of.the.biofabrication.and.the.tightly.controlled.fine.tuning. of. specific. features. of. the. product.. There. are. several. relevant. modules.
of.the.process.chain:.(1).composition.of.the.culture.medium;.(2).design.and.
mode. of. action. of. the. bioreactor;. (3). process. parameters. (e.g.,. temperature,.
time,.gas.concentration);.and.(4).postprocessing.steps.(e.g.,.drying,.pressing,.
perforation,.inclusion.of.composite.partners).
Most.importantly,.the.structure.and.properties.of.the.BNC.strongly.depend.
on.the.choice.of.the.cellulose-forming.bacterial.strain..The.differences.in.the.
structure.and.properties.of.BNC.fleeces.are.exemplified.using.four.selected.
BNC-producing. Gluconacetobacter. strains:. DSM. 14666,. ATCC. 10245,. ATCC.
53582,.and.ATCC.23769.(DSM,.Deutsche.Sammlung.von.Mikroorganismen.
und.Zellkulturen;.ATCC,.American.Type.Culture.Collection).(Wesarg.et.al..
2010)..The.strains.DSM.14666.and.ATCC.53582,.for.example,.produce.stable.
hydrogel.bodies..In.contrast,.the.fleeces.generated.by.ATCC.53582.and.ATCC.
23769. are. significantly. less. stable.. Such. structural. differences. may. significantly.affect.the.material.characteristics.
In.Table 9.1.typical.parameters.of.the.BNC.materials.produced.by.the.four.
teristics.(tensile.strength,.compressive.stress,.water.retention.value,.and.storage.modulus).are.presented.and.compared.to.the.degree.of.polymerization.
and.the.crystallinity.of.the.respective.products..BNC.samples.produced.by.
DSM.14666.and.ATCC.53582.are.characterized.by.considerably.higher.values.
of.tensile.strength.and.compressive.stress.in.comparison.to.those.of.the.more.
labile.samples.produced.by.ATCC.10245.and.ATCC.23769..Concordantly,.the.
two.stable.BNC.samples.show.a.higher.water.retention.value.and.a.slightly.
higher.crystallinity.than.the.labile.ones..The.concurrently.increased.storage.
modulus.G′.of.the.two.stable.BNC.samples.was.interpreted.by.the.authors.as.
an.indication.of.a.correlation.between.. augmented.crystallinity.and.elasticity.
Since.the.determination.of.further.material.characteristics,.and.especially.
ventional.methods.shows.severe.technical.limitations,.specific.characterization.techniques.for.hydrogels.have.been.developed.by.the.American.Society.