Biomedical Engineering Reference
In-Depth Information
NP33-HER
NP20-HER
NP20
NP10-HER
200
300
400
500
600
Binding Energy (eV)
700
800
900
1000
FIGURE 8.4
X-ray. photoelectron. spectroscopy. (XPS). wide-scan. spectra. of. the. docetaxel-loaded. PLA-TPGS/TPGS-COOH.
nanoparticles..(Reproduced.with.permission.from.Sun.et.al.,.
Nanomedicine
4(4):.431-445,.2009.)
docetaxel-loaded. NPs. of. various. component. copolymer. blend. ratios.. From. their. chemi-
cal. structure,. it. can. be. seen. that. PLA-TPGS. and. TPGS-COOH. do. not. contain. any. nitro-
gen.atoms,.while.docetaxel.and.trastuzumab.contain.nitrogen.atoms..Therefore,.nitrogen.
could.be.used.as.a.marker.to.detect.the.presence.of.docetaxel.and.trastuzumab.on.the.NP.
surfaces..It.can.be.seen.from.the.third.spectrum.from.the.top.(for.NP20).in.Figure 8.4.that.
there. is. no. N. 1s. signal. at. the. 397.6. eV. bond. energy. position,. which. means. there. are. no.
docetaxel.molecules.on.the.NP.surface..This.agrees.with.our.earlier.research.on.paclitaxel-
loaded. polymeric. nanoparticles. prepared. with. either. phospholipids. or. PVA. or. TPGS. as.
emulsiier..The.second.spectrum.from.the.top.(for.NP20-HER),.however,.the.nitrogen.peak.
at.the.397.6.eV.bond.energy.position.(as.shown.in.the.circle.in.Figure 8.4).must.come.from.
trastuzumab,.which.conirms.the.successful.conjugation.of.trastuzumab.on.the.NP.sur-
face..It.can.be.seen.from.a.close.comparison.of.the.XPS.spectra.among.NP10-HER,.NP20-
HER,.and.NP33-HER.that.there.was.an.increase.in.the.percentage.of.the.N.1s.region;.as.
the.more.TPGS-COOH.is.included.in.the.polymeric.matrix,.the.more.trastuzumab.can.be.
conjugated.on.the.NP.surface.
8.5.6 In Vitro Docetaxel-Release Kinetics
Figure 8.5. shows. the. 30-day. in. vitro. release. proiles. of. docetaxel. from. the. drug-loaded.
PLA-TPGS/TPGS-COOH.NPs.with.and.without.trastuzumab.conjugation..Docetaxel.was.
released.from.the.NPs.in.a.pH.7.4.PBS.buffer.at.37°C..From.Figure 8.5,.it.can.be.seen.that.
docetaxel.was.released.in.a.biphasic.style.with.an.initial.burst.and.subsequent.accumula-
tive. release.. It. is. obvious. that. the. drug. release. of. NPs. with. trastuzumab. conjugation. is.
signiicantly.faster.than.that.without.trastuzumab.conjugation,.which.means.modiication.
of.the.NP.surface.signiicantly.speeds.up.the.drug.release..This.can.be.explained.by.effects.
of.the.surface.modiication.on.the.surface.morphology,.which.makes.the.NPs.blurry.and.
thus.increases.the.surface.area,.which.increases.the.speed.at.which.the.drug.is.released.
from.the.NPs.
