Biomedical Engineering Reference
In-Depth Information
A
B
NUS_CHBE
SEI
5.0 kV ×30,000
100 nm WD7.9 mm NUS_CHBE
SEI 5.0 kV
×45,000
100 nm WD 7.6mm
FIGURE 8.3
FESEM.images.of.docetaxel-loaded.nanoparticles.of.PLA-TPGS.(67%).and.TPGS-COOH.(33%).copolymer.blend:.(A).
NP33.and.(B).NP33-HER..(Reproduced.with.permission.from.Sun.and.Feng,.
Nanomedicine
,.4(4):.431-445,.,.2009.)
and. the. NPs.. A. low. absolute. value. of. the. zeta. potential. indicates. colloidal. instability,.
which.could.lead.to.aggregation.of.the.NPs.in.dispersion..A.high.absolute.value.of.the.zeta.
potential.indicates.a.high.surface.charge.of.the.NPs,.which.leads.to.strong.repellent.inter-
actions.among.the.NPs.in.dispersion,.and.thus.high.stability..It.can.be.seen.from.Table 8.1.
that. the. zeta. potential. of. docetaxel-loaded. PLA-TPGS/TPGS-COOH. NPs. without. tras-
tuzumab.modiication.was.found.to.be.around.-40 mV,.indicating.that.the.nanoparticle.
dispersion.is.stable..The.absolute.values.of.zeta.potential.for.trastuzumab-functionalized.
NPs.are.lower.than.those.without.trastuzumab.on.the.surface,.and.the.more.trastuzumab.
on.the.surface,.the.lower.the.absolute.values.were..This.is.because.of.the.positive.charge.
of.trastuzumab.
8.5.4 Drug Encapsulation Efficiency
The.drug.encapsulation.eficiency.(EE).of.the.docetaxel-loaded.PLA-TPGS/TPGS-COOH.
NPs.is.also.included.in.Table 8.1,.from.which.it.can.be.found.that.(1).the.EE.data.have.no.
signiicant.difference.among.all.types.of.NPs,.and.(2).the.slight.difference.in.EEs.among.all.
types.of.NPs.is.caused.by.the.component.ratio.between.PLA-TPGS.and.TPGS-COOH..For.
example,.the.EE.of.NP20,.which.contains.20%.TPGS-COOH,.is.the.highest.among.all.the.
NPs..Either.lower.or.higher.content.of.TPGS-COOH.in.the.polymeric.matrix.caused.lower.
EE..Surface.functionalization.should.increase.the.EE.in.general.since.it.would.decrease.the.
drug.diffusion.from.the.NPs.into.the.aqueous.phase.in.the.preparation.process..However,.
drug.diffusion.from.the.NPs.should.also.depend.on.the.porosity.of.the.NP.matrix..The.
porosity.of.the.polymeric.matrix.would.be.high.if.too.much.TPGS-COOH.was.included,.
which.would.speed.the.drug.diffusion.from.the.NPs.into.the.aqueous.phase.in.the.prepa-
ration.process.
8.5.5 Surface Chemistry
X-ray. photoelectron. spectroscopy. (XPS). was. applied. to. study. the. surface. chemistry. of.
the. docetaxel-loaded. PLA-TPGS/TPGS-COOH. NPs. with. or. without. surface. modiica-
tion.. Figure 8.4. shows. the. XPS. wide-scan. spectrum. of. the. trastuzumab-functionalized,.
