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Colloidal Stability and Magnetophoresis of Gold-Coated Iron Oxide Nanorods in Biological Media
journal contribution
posted on 2012-10-25, 00:00 authored by Swee Pin Yeap, Pey Yi Toh, Abdul
Latif Ahmad, Siew Chun Low, Sara A. Majetich, JitKang LimMagnetic iron oxide nanorods are coated with a gold colloid
(Fe/Au
NRs) to form core–shell particles that combine magnetic and
plasmonic properties in a single nanostructure. Three different macromolecules
are employed to surface functionalize the nanorod in order to promote
colloidal stability of these particles in elevated ionic strength
media (∼154 mM NaCl equivalent) that are appropriated for biomedical
applications. With a 10 000 molecular weight poly(ethylene
glycol) (PEG), the NRs flocculated and sedimented within a few minutes.
However, Pluronic F127 or poly(diallyldimethylamonium chloride) (PDDA)
coatings yielded stable dispersions for up to 20 h. These NRs exhibit
two absorbance peaks at 530 nm and ∼740 nm corresponding to
the transverse and longitudinal surface plasmon resonances (SPR).
In addition to dynamic light scattering (DLS), spectrophotometry can
also be used to monitor dispersion stability because the 530 nm SPR
peak shape changes when agglomerates form. The magnetophoretic migration
time of these particles, monitored by suspension opacity measurement
by light dependent resistor (LDR) under low gradient magnetic separation
(LGMS), was prolonged from 1.5 min to ∼8 min after surface
functionalization.
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NRs exhibitdispersion stabilityPDDAmagnetophoretic migration time530 nm SPR peak shape changes530 nmgold colloidLDR1.5 min10 000DLSColloidal Stabilityabsorbance peaksBiological MediaMagnetic iron oxide nanorodssurface functionalizeLGMSpolyPEGsuspension opacity measurementPluronic F 127agglomerates form20 hsurface functionalizationplasmonic propertiessurface plasmon resonances
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