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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.


TEM images of iron oxide–PNIPAMcore–shell nanoparticles formed by ligand exchange grafting-tosynthesis, (A) core, 3.9 nm, PNIPAM 10 kDa; (B) core 10.7 nm, PNIPAM20 kDa; or grafting-from polymerization (C) core 5.6 nm, PNIPAM 70kDa.
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fig2: TEM images of iron oxide–PNIPAMcore–shell nanoparticles formed by ligand exchange grafting-tosynthesis, (A) core, 3.9 nm, PNIPAM 10 kDa; (B) core 10.7 nm, PNIPAM20 kDa; or grafting-from polymerization (C) core 5.6 nm, PNIPAM 70kDa.

Mentions: The PNIPAM-grafted core–shell nanoparticles were inspectedby TEM and showed highly monodisperse, individually separated nanoparticlesdried on the grid, with no change to core morphology (Figure 2). For particles produced bygrafting-from, some clusters of cores could be observed on the grid(see the Supporting Information, FigureS9). Although the bulk aggregation state of nanoparticles cannot bedirectly determined after drying onto TEM grids, it is possible thatthe difficulty to disperse the initiator-coated cores in water mixturesat the start of the polymerization led to some growth proceeding fromaggregated clusters of cores and that it is those aggregates thatare observed on the TEM grid. The cores in such clusters would effectivelyshare a common dense PNIPAM shell. The grafting-from samples had amuch lighter color than the grafting-to samples; this is also indicativeof a nonhomogenous distribution of cores at the same concentration.If clusters are indeed present, it means that the local grafting densityfor the exposed surface of the grafting-from particles presented in Table 1 should be adjustedslightly upward; however, it also results in an intrinsic higher polydispersitydue to the fraction of clusters.


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

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

TEM images of iron oxide–PNIPAMcore–shell nanoparticles formed by ligand exchange grafting-tosynthesis, (A) core, 3.9 nm, PNIPAM 10 kDa; (B) core 10.7 nm, PNIPAM20 kDa; or grafting-from polymerization (C) core 5.6 nm, PNIPAM 70kDa.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4559841&req=5

fig2: TEM images of iron oxide–PNIPAMcore–shell nanoparticles formed by ligand exchange grafting-tosynthesis, (A) core, 3.9 nm, PNIPAM 10 kDa; (B) core 10.7 nm, PNIPAM20 kDa; or grafting-from polymerization (C) core 5.6 nm, PNIPAM 70kDa.
Mentions: The PNIPAM-grafted core–shell nanoparticles were inspectedby TEM and showed highly monodisperse, individually separated nanoparticlesdried on the grid, with no change to core morphology (Figure 2). For particles produced bygrafting-from, some clusters of cores could be observed on the grid(see the Supporting Information, FigureS9). Although the bulk aggregation state of nanoparticles cannot bedirectly determined after drying onto TEM grids, it is possible thatthe difficulty to disperse the initiator-coated cores in water mixturesat the start of the polymerization led to some growth proceeding fromaggregated clusters of cores and that it is those aggregates thatare observed on the TEM grid. The cores in such clusters would effectivelyshare a common dense PNIPAM shell. The grafting-from samples had amuch lighter color than the grafting-to samples; this is also indicativeof a nonhomogenous distribution of cores at the same concentration.If clusters are indeed present, it means that the local grafting densityfor the exposed surface of the grafting-from particles presented in Table 1 should be adjustedslightly upward; however, it also results in an intrinsic higher polydispersitydue to the fraction of clusters.

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.