231
Biomimetic Mineralization of Apatite on Bacterial Cellulose
of.OCP.to.HA..In.addition,.the.appearance.of.the.CO 3
2− .band.at.873–875/cm.
starting.from.the.7-day.spectra.indicated.the.formation.of.carbonated.apatitic.phase.(type.B.carbonate),.where.CO 3
2– .groups.were.replaced.at.the.site.
of.PO 4
3– .groups.in.the.apatitic.lattice.(Elliott.et.al..1985;.Rey.et.al..1989)..The.
spectral. feature. of. 21. days. was. typical. of. a. calcium-deficient. carbonated.
apatite,.which.has.been.widely.reported.as.a.bonelike.apatite.because.of.its.
similar.spectral.features.with.those.of.bone.tissues.(Elliott.et.al..1985;.Rey.
et.al..1989,.1991a,.1991b)..From.ATR-FTIR.spectral.data.and.the.value.of.the.
Ca:P.ratio,.the.crystalline.phase.nucleated.on.the.BC.microfibril.surface.was.
calcium-deficient.carbonated.apatite.through.the.initial.formation.of.OCP.or.
OCP-like.Ca-P.phase.
BC Templates Alternatively Soaked in Calcium and Phosphate Solutions
Templates.of.native.BC,.BC-TEMPO,.BC-TEMPO-Ca,.and.BC-GlcNAc.were.used.
for.five.alternate.soaking.cycles.(Nge.et.al..2010a)..The.alternate.soaking.method.
showed.a.similar.result.as.that.of.soaking.in.1.5.SBF,.where.the.newly.formed.
Ca-P.globules.varied.in.size.between.different.BC.templates.(Figure 11.5)..The.
globule.size.formed.on.native.BC.and.BC-TEMPO.were.4–6.μm.and.1.5–2.μm,.
mately.3.μm.and.1.5.μm.for.native.BC.and.BC-TEMPO,.respectively..The.globules.on.BC-TEMPO-Ca,.however,.have.a.similar.size.(<1.μm).with.both.soaking.
methods.. The. distinctively. larger. size. formed. on. the. microfibril. surface. of.
native.BC.may.be.due.to.a.relatively.higher.ion.concentration.as.well.as.to.a.
more.rapid.soaking.cycle.(30.min.interval.for.a.total.of.about.5.h,.as.opposed.to.
21.days.for.the.1.5.SBF.soaking.method),.which.accelerates.the.increase.in.size.
of.the.crystals.and.the.progressive.mineralization.nature.of.native.BC.
The. nature. of. the. multiplication. mineralization. that. occurred. in. the.
BC-TEMPO. and. BC-TEMPO-Ca. templates,. however,. seems. independent. of.
the. soaking. methods.. A. more. defined. morphology. of. apatite. globule. was.
observed.on.the.lower.surface.of.the.BC.templates,.as.the.lower.surface.layer.of.
the.BC.pellicle.consists.in.general.of.a.looser.network.than.the.upper.surface.
layer..For.example,.the.apatite.globule.with.a.honeycomb-like.3D.structure.
composed.of.thin.platelike.crystals.was.observed.in.BC-TEMPO,.and.a.cluster.of.thin.platelike.crystals.spreading.upward.in.all.directions.was.observed.
in.BC-TEMPO-Ca,.as.shown.in.Figures 11.5g.and.11.5h..It.should.be.noted.
that. the. surface. functional. groups. or. surface. structure. plays. an. important.
role.in.the.initial.step.of.apatite.nucleation.and.governs.the.following.mineralization.process.by.either.multiplication.or.progressive.mineralization.
On. the. other. hand,. the. apatite-deposited. BC-GlcNAc. surface. in.
Figures  11.5d–f. showed. a. different. morphology,. where. the. Ca-P. mineralization. may. take. place. along. the. surface. with. the. initial. formation. of. a.
monolayer.followed.by.the.formation.of.apatite.globules. (1–1.5.μm).on.the.
existing.monolayer..The.proportion.of.incorporated.GlcNAc.and.the.type.of.
starter.culture.used.for.the.inoculation.also.affect.the.morphology.of.apatite.