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Synthesis and Magneto-Thermal Actuation of Iron Oxide Core-PNIPAM Shell Nanoparticles.

Kurzhals S, Zirbs R, Reimhult E - ACS Appl Mater Interfaces (2015)

Bottom Line: Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine.Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them.The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction.

View Article: PubMed Central - PubMed

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

ABSTRACT
Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine. In this paper, it is demonstrated how the excellent colloidal stability and magnetic properties of monodisperse and individually densely grafted iron oxide nanoparticles can be used to manipulate reversibly the solubility of nanoparticles with a poly(N-isopropylacrylamide)nitrodopamine shell. "Grafting-to" and "grafting-from" methods for synthesis of an irreversibly anchored brush shell to monodisperse, oleic acid coated iron oxide cores are compared. Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them. The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction.

No MeSH data available.


ATR-FTIR measurementsfor oleic acid coated iron oxide nanoparticles and PNIPAM functionalizednanoparticles synthesized with both the grafting-to and grafting-frommethods. Characteristic peak for free or physisorbed oleic acid (markedby *) is absent for the PNIPAM-iron oxide core–shell particles.Characteristic bands at 3280, 1640, and 1540 cm–1 marked with light blue shadow can be assigned to the NH protonsand the amide bond of the grafted PNIPAM.
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fig1: ATR-FTIR measurementsfor oleic acid coated iron oxide nanoparticles and PNIPAM functionalizednanoparticles synthesized with both the grafting-to and grafting-frommethods. Characteristic peak for free or physisorbed oleic acid (markedby *) is absent for the PNIPAM-iron oxide core–shell particles.Characteristic bands at 3280, 1640, and 1540 cm–1 marked with light blue shadow can be assigned to the NH protonsand the amide bond of the grafted PNIPAM.

Mentions: Figure 1 shows attenuated total reflection-Fouriertransform infrared spectroscopy (ATR-FTIR) measurements of the grafting-toand grafting-from samples. The spectra of the grafting-to samplesconfirm successful ligand exchange from oleic acid to catechol-modifiedPNIPAM, with new bands at 3280, 1640, and 1540 cm–1 that can be assigned to the NH protons and the amide bond of thegrafted polymer.48 The broad band in therange of 400 to 600 cm–1 can be assigned to thepresence of the iron oxide core. The spectrum of the grafting-fromsample resembles the grafting-to products, which demonstrates successfulpolymerization of PNIPAM shells on the cores. A small sideband at1725 cm–1 is attributed to the ester bond of thesurface bound initiator. The presence of bound oleic acid cannot beexcluded by evaluating characteristic bands in the range from 1420to 1550 cm–1, because the polymer bands dominatethe spectrum in this region. However, a characteristic peak of freeor physisorbed oleic acid49,50 at 1702 cm–1 was not present in the final product. The difficulty of totallyreplacing oleic acid even with a more strongly binding dispersantwas recently demonstrated.41


Synthesis and Magneto-Thermal Actuation of Iron Oxide Core-PNIPAM Shell Nanoparticles.

Kurzhals S, Zirbs R, Reimhult E - ACS Appl Mater Interfaces (2015)

ATR-FTIR measurementsfor oleic acid coated iron oxide nanoparticles and PNIPAM functionalizednanoparticles synthesized with both the grafting-to and grafting-frommethods. Characteristic peak for free or physisorbed oleic acid (markedby *) is absent for the PNIPAM-iron oxide core–shell particles.Characteristic bands at 3280, 1640, and 1540 cm–1 marked with light blue shadow can be assigned to the NH protonsand the amide bond of the grafted PNIPAM.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4559841&req=5

fig1: ATR-FTIR measurementsfor oleic acid coated iron oxide nanoparticles and PNIPAM functionalizednanoparticles synthesized with both the grafting-to and grafting-frommethods. Characteristic peak for free or physisorbed oleic acid (markedby *) is absent for the PNIPAM-iron oxide core–shell particles.Characteristic bands at 3280, 1640, and 1540 cm–1 marked with light blue shadow can be assigned to the NH protonsand the amide bond of the grafted PNIPAM.
Mentions: Figure 1 shows attenuated total reflection-Fouriertransform infrared spectroscopy (ATR-FTIR) measurements of the grafting-toand grafting-from samples. The spectra of the grafting-to samplesconfirm successful ligand exchange from oleic acid to catechol-modifiedPNIPAM, with new bands at 3280, 1640, and 1540 cm–1 that can be assigned to the NH protons and the amide bond of thegrafted polymer.48 The broad band in therange of 400 to 600 cm–1 can be assigned to thepresence of the iron oxide core. The spectrum of the grafting-fromsample resembles the grafting-to products, which demonstrates successfulpolymerization of PNIPAM shells on the cores. A small sideband at1725 cm–1 is attributed to the ester bond of thesurface bound initiator. The presence of bound oleic acid cannot beexcluded by evaluating characteristic bands in the range from 1420to 1550 cm–1, because the polymer bands dominatethe spectrum in this region. However, a characteristic peak of freeor physisorbed oleic acid49,50 at 1702 cm–1 was not present in the final product. The difficulty of totallyreplacing oleic acid even with a more strongly binding dispersantwas recently demonstrated.41

Bottom Line: Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine.Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them.The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction.

View Article: PubMed Central - PubMed

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

ABSTRACT
Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine. In this paper, it is demonstrated how the excellent colloidal stability and magnetic properties of monodisperse and individually densely grafted iron oxide nanoparticles can be used to manipulate reversibly the solubility of nanoparticles with a poly(N-isopropylacrylamide)nitrodopamine shell. "Grafting-to" and "grafting-from" methods for synthesis of an irreversibly anchored brush shell to monodisperse, oleic acid coated iron oxide cores are compared. Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them. The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction.

No MeSH data available.