Biomedical Engineering Reference
In-Depth Information
BSA.on.the.surface.of.PLLACL.iber.mats.because.the.inner.and.outer.BSA.solutions.could.
not. mix. together. completely.. Thus,. there. were. also. initial. stages. in. the. release. proiles.
of.the.coaxial.PLLACL.iber.mats,.but.they.were.quite.different.from.those.of.the.mixed.
PLLACL.iber.mats.
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Zhang. et. al.
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. also. studied. the. encapsulation. of. a. model. protein,. luorescein. isothio-
cyanate-conjugated.bovine.serum.albumin.(FITC-BSA),.along.with.poly(ethylene.glycol).
(PEG),.within.biodegradable.poly(ε-caprolactone).(PCL).iber.mats,.by.using.coaxial.elec-
trospinning..They.varied.the.inner.low.rates.from.0.2.to.0.6.ml/h,.with.a.constant.outer.
low. rate. of. 1.8. ml/h,. and. the. amount. of. FITC-BSA. loading. from. 0.85. to. 2.17. mg/g. of.
iber.mats,.and.investigated.the.release.characteristics.of.FITC-BSA.from.iber.mats..For.
comparing. the. effectiveness. of. the. coaxial. electrospinning. technique,. the. same. mate-
rials. were. prepared. into. the. iber. mats. by. using. the. conventional. single-luid. electro-
spinning.method..The.release.characteristics.of.FITC-BSA.from.iber.mats.were.studied.
by.immersion.in.phosphate.buffered.saline.(PBS;.pH.7.4).at.37°C..They.found.that.the.
release.of.BSA.from.the.core-shell.structure.ibers.was.continuous.over.a.period.of.more.
than.5.months..Moreover,.the.release.rate.of.smaller-sized.ibers.was.faster.than.that.of.
larger-sized.ibers..Compared.with.the.iber.mats.from.conventional.single-luid.elec-
trospinning,.the.core-shell.iber.mats.could.retard.the.initial.burst.release.
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.Lu.et al.
74
.
prepared.composite.iber.mats.composed.of.cationized.gelatin-coated.polycaprolactone.
(PCL).by.coaxial.electrospinning..Cationized.gelatin.(CG).was.used.as.the.shell.materi-
als.for.fabricating.core-shell.iber.mats..They.investigated.the.adsorption.behaviors.of.
FITC-labeled. bovine. serum. albumin. (FITC-BSA). or. FITC-heparin. onto. the. iber. mats..
Moreover,. vascular. endothelial. growth. factor. (VEGF). was. impregnated. into. the. iber.
mats. through. speciic. interactions. with. the. adsorbed. heparin. in. the. outer. CG. layer..
The.CG.iber.mats.were.cross-linked.by.exposing.the.iber.mats.in.glutaraldehyde.(GA).
vapor..Lu.et.al..found.that.the.release.characteristics.of.BSA.or.heparin.from.core-shell.
iber.mats.exhibited.a.slight.burst.release.within.the.irst.2.h,.and.there.was.negligible.
desorption.from.the.iber.mats.for.both.BSA.and.heparin..Moreover,.the.release.rate.of.
heparin.could.be.controlled.by.varying.the.cross-linking.density.of.the.outer.CG.iber.
mats.. Sustained. release. of. VEGF. could. be. achieved. from. the. heparin-adsorbed. iber.
mats.for.more.than.15.days.
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Core-shell.structure.devices.are.generally.used.for.incorporating.proteins.because.they.
can.preserve.an.unstable.biological.agent.from.harsh.environments.and.functionalize.the.
surface. of. materials. without. affecting. the. core. materials.. Emulsion-electrospinning. was.
the.one.novel.process.to.prepare.core-shell.structures..It.is.remarkable.that.unlike.coaxial.
electrospinning,. which. needs. a. special. apparatus,. this. technique. uses. basic. equipment,.
such.as.a.single.needle..The.composite.ibers.with.beads-in-string.structures.were.success-
fully.prepared.by.emulsion-electrospinning.
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.Ca-alginate.microspheres.were.loaded.with.
bovine. serum. albumin. (BSA). by. W/O. emulsion,. and. then. were. embedded. into. poly(L-
lactic.acid).(PLLA).ibers.by.electrospinning..For
in.vitro.release.study,.the.release.of.BSA.
from.composite.ibers.exhibited.prolonged.release.proiles.and.lower.initial.burst.release.
rates.than.those.from.naked.Ca-alginated.microspheres.
75
.Maretschek.et.al.
76
.also.prepared.
cytochrome.C.(hydrophilic.model.protein)-loaded.iber.mats.based.on.PLLA.by.emulsion-
electrospinning.. The. release. behaviors. of. protein-loaded. PLLA. iber. mats. derived. from.
1,.2,.or.3.wt%.PLLA.solution.were.studied.in.PBS.(pH.7.4)..PLLA.iber.mats.from.2.and.3.
wt%.solutions.exhibited.no.burst.release,.which.implied.perfect.inclusion.of.the.protein.
within.the.iber.mats..The.slight.increase.in.the.protein.release.from.1.wt%.PLLA.solutions.
might.be.due.to.the.decrease.in.thickness.of.the.iber.mats,.which.leads.to.better.wetta-
bility..To.study.the.effect.of.wettability.on.cytochrome.C.release,.releasing.media.having.
