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Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles.

Bixner O, Lassenberger A, Baurecht D, Reimhult E - Langmuir (2015)

Bottom Line: Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface.A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented.The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultrasmall core-shell architectures.

View Article: PubMed Central - PubMed

Affiliation: Department of Nanobiotechnology, Institute for Biologically Inspired Materials, University of Natural Resources and Life Sciences Vienna , Muthgasse 11, 1190 Vienna, Austria.

ABSTRACT
High-temperature synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decomposition products. Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. We evaluate by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) the limitations of commonly used approaches. A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented. The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultrasmall core-shell architectures.

No MeSH data available.


Related in: MedlinePlus

TGA (solidlines) and DSC curves (dashed lines) of representative3.5 nm SPION preparations measured in synthetic air: as-synthesizedOA–SPION containing excess physisorbed oleic acid (black, stars),purified OA–SPION with an oleate monolayer (gray, squares),column-chromatographed SPION with physisorbed impurities (magenta,diamonds), cold MeOH-extracted mixed dispersant SPION containing around5% w/w physisorbed OA (green, triangles), CTAB-treated mixed dispersantSPION free of physisorbed OA (blue, circles), and spectroscopicallyclean P-NDA post-coated SPION (red, triangles).
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fig3: TGA (solidlines) and DSC curves (dashed lines) of representative3.5 nm SPION preparations measured in synthetic air: as-synthesizedOA–SPION containing excess physisorbed oleic acid (black, stars),purified OA–SPION with an oleate monolayer (gray, squares),column-chromatographed SPION with physisorbed impurities (magenta,diamonds), cold MeOH-extracted mixed dispersant SPION containing around5% w/w physisorbed OA (green, triangles), CTAB-treated mixed dispersantSPION free of physisorbed OA (blue, circles), and spectroscopicallyclean P-NDA post-coated SPION (red, triangles).

Mentions: Multistep TGA profiles observed below 400 °Chave previouslybeen attributed alternatively to vaporization of physisorbed OA,15 to chemisorbed oleate species with differentbinding strengths,33 or to partial cleavageof the capping agent.29 In our experiments,a significant second step in TGA was only observed when physisorbedOA or other impurities were present (Figure 3 and SI 3.2 ofthe Supporting Information). Also, by comparison of the FTIR spectraof the tested particles to the TGA/DSC data, the presence of minoramounts of residual-free OA (around 5% w/w) could not be reliablydetected with TGA/DSC (Table 1, Figures 2 and 3, and SI 3.2 of the Supporting Information) using a difference in the decompositionprofile as the basis for detection.


Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles.

Bixner O, Lassenberger A, Baurecht D, Reimhult E - Langmuir (2015)

TGA (solidlines) and DSC curves (dashed lines) of representative3.5 nm SPION preparations measured in synthetic air: as-synthesizedOA–SPION containing excess physisorbed oleic acid (black, stars),purified OA–SPION with an oleate monolayer (gray, squares),column-chromatographed SPION with physisorbed impurities (magenta,diamonds), cold MeOH-extracted mixed dispersant SPION containing around5% w/w physisorbed OA (green, triangles), CTAB-treated mixed dispersantSPION free of physisorbed OA (blue, circles), and spectroscopicallyclean P-NDA post-coated SPION (red, triangles).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4554299&req=5

fig3: TGA (solidlines) and DSC curves (dashed lines) of representative3.5 nm SPION preparations measured in synthetic air: as-synthesizedOA–SPION containing excess physisorbed oleic acid (black, stars),purified OA–SPION with an oleate monolayer (gray, squares),column-chromatographed SPION with physisorbed impurities (magenta,diamonds), cold MeOH-extracted mixed dispersant SPION containing around5% w/w physisorbed OA (green, triangles), CTAB-treated mixed dispersantSPION free of physisorbed OA (blue, circles), and spectroscopicallyclean P-NDA post-coated SPION (red, triangles).
Mentions: Multistep TGA profiles observed below 400 °Chave previouslybeen attributed alternatively to vaporization of physisorbed OA,15 to chemisorbed oleate species with differentbinding strengths,33 or to partial cleavageof the capping agent.29 In our experiments,a significant second step in TGA was only observed when physisorbedOA or other impurities were present (Figure 3 and SI 3.2 ofthe Supporting Information). Also, by comparison of the FTIR spectraof the tested particles to the TGA/DSC data, the presence of minoramounts of residual-free OA (around 5% w/w) could not be reliablydetected with TGA/DSC (Table 1, Figures 2 and 3, and SI 3.2 of the Supporting Information) using a difference in the decompositionprofile as the basis for detection.

Bottom Line: Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface.A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented.The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultrasmall core-shell architectures.

View Article: PubMed Central - PubMed

Affiliation: Department of Nanobiotechnology, Institute for Biologically Inspired Materials, University of Natural Resources and Life Sciences Vienna , Muthgasse 11, 1190 Vienna, Austria.

ABSTRACT
High-temperature synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decomposition products. Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. We evaluate by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) the limitations of commonly used approaches. A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented. The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultrasmall core-shell architectures.

No MeSH data available.


Related in: MedlinePlus