Biomedical Engineering Reference
In-Depth Information
A
B
C
FIGURE 11.8
Inluence. of. drying. method. on. the. morphology. of. PLGA. nano-microcapsules.. (A). Air. dried. (30,000×)..
(B) Lyophilization.(3,000×)..(C).Vacuum.oven.dried.at.room.temperature.(3000×).
11.2.2.2.2.1 Preparation
Nanocapsules.are.prepared.in.a.different.way.than.the.spheres.
to.create.the.wall..In.the.studies.presented,.the.capsules.were.loaded.with.water-soluble.
drugs.in.the.core.and.hydrophobic.drugs.in.the.shell.component.
PLGA. and. PHBV. nano-microcapsules. were. prepared. by. a. double-emulsion. (w
1
/o/
w
2
). technique.. Briely,. after. the. polymer. is. dissolved. in. an. organic. solvent. (e.g.,. dichlo-
romethane.DCM),.a.smaller.volume.of.aqueous.phase.carrying.the.drug.is.added.into.this.
solution.and.agitated.to.form.an.emulsion.of.the.water.phase.in.the.organic.phase,.the.size.
of.the.droplets.of.which.is.controlled.by.the.agitation.(sonication).level..This.emulsion.is.
then.added.into.a.much.larger.volume.of.the.aqueous.phase.containing.the.emulsiier.to.
form. the. nano-microcapsules.. Evaporation. of. the. organic. solvent,. separation. of. the. cap-
sules,.and.drying.were.carried.out.as.mentioned.in.Section.11.2.2.2.1.1.
11.2.2.2.2.2 Characterization of PLGA and PHBV Nano-Microcapsules
Particle. size,. SEM,.
and. luorescence. microscopy. are. used. to. examine. the. physical. properties. (morphology,.
size,.size.distribution).of.the.PLGA.nano-microcapsules,.and.this.information.is.then.used.
to.optimize.the.procedure..In.Figure 11.8.the.effect.of.the.drying.method.on.capsule.topog-
raphy.is.presented.
In.this.study,.the.nano-microcapsules.were.obtained.in.a.DCM-water.medium,.as.was.
mentioned. in. Section. 11.1.2.2.2.1,. and. again. drying. at. room. temperature. (RT). without.
any.special.devices.was.found.to.be.the.best.drying.method.in.terms.of.obtaining.round,.
smooth,.and.unagglomerated.capsules.(Figure 11.8A).
Determination.of.the.size.of.the.PLGA.nano-microcapsules.by.dynamic.light.scattering.
revealed.that.the.particle.sizes.were.in.the.range.200.nm-10.µm,.and.the.average.diameter.
was.2.µm.
The.morphologies.of.PHBV.nano-microcapsules.loaded.with.calcein.(a.model.drug.luo-
rescent.molecule).were.also.evaluated.by.luorescence.microscopy.and.SEM.(Figure 11.9)..
Their.particle.size.range.was.300.nm-20.µm,.and.the.average.diameter.was.found.to.be.
8 µm..This.indicates.that.the.loading.process.led.to.an.increase.in.size..The.use.of.luo-
rescent.molecule.had.an.advantage;.it.made.the.nano-microcapsule.easily.detectable.with.
luorescence.microscope.(Figure 11.9A).
11.2.2.2.3 Uptake of PLGA and PHBV Nano-Microcapsules by Saos-2 Cells
The.uptake.of.nano-microcapsules.of.PLGA.and.PHBV.was.studied.in.vitro.with.osteosar-
coma.cells.(Saos-2)..The.results.were.evaluated.after.incubation.of.the.capsules.for.4.h.in.
the.cell.culture.medium.
