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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.


Related in: MedlinePlus

Sample (10.7 nm/PNIPAM 20 kDa, 5 mg/mL) in apoly(methyl methacrylate) (PMMA) cuvette placed upon a neodym magnet,(A) at room temperature, (B) at 40 °C. In plastic cuvettes, adiscoloration of the cuvette wall remains, interpreted as a high affinityof the dehydrated PNIPAM for the cuvette walls.
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fig4: Sample (10.7 nm/PNIPAM 20 kDa, 5 mg/mL) in apoly(methyl methacrylate) (PMMA) cuvette placed upon a neodym magnet,(A) at room temperature, (B) at 40 °C. In plastic cuvettes, adiscoloration of the cuvette wall remains, interpreted as a high affinityof the dehydrated PNIPAM for the cuvette walls.

Mentions: Figure 4A shows the stability of the 10.7 nm core/20kDa PNIPAM superparamagnetic particles to the magnetic field producedby a strong permanent magnet at room temperature below the LCST; allthe individually stabilized particles remain dispersed. Upon heatingto 40 °C (above the LCST of 32 °C), the core–shellparticles weakly aggregate as shown by the DLS measurements above.The aggregates in the turbid particle dispersion can then be attractedby the same magnetic field (Figure 4B). The almost complete extraction of nanoparticlesobserved at moderate heating with a standard magnet contrasts to theincomplete withdrawal demonstrated earlier by nanoparticles with aphysisorbed block copolymer PNIPAM shell architecture11 or by polydisperse PNIPAM-grafted nanoparticles.19 Upon cooling below the LCST, the brown precipitatewas redissolved by gentle shaking, demonstrating the reversibilityof the process and the stability of the core–shell nanoparticlesagainst thermal stress.


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

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

Sample (10.7 nm/PNIPAM 20 kDa, 5 mg/mL) in apoly(methyl methacrylate) (PMMA) cuvette placed upon a neodym magnet,(A) at room temperature, (B) at 40 °C. In plastic cuvettes, adiscoloration of the cuvette wall remains, interpreted as a high affinityof the dehydrated PNIPAM for the cuvette walls.
© Copyright Policy
Related In: Results  -  Collection

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

fig4: Sample (10.7 nm/PNIPAM 20 kDa, 5 mg/mL) in apoly(methyl methacrylate) (PMMA) cuvette placed upon a neodym magnet,(A) at room temperature, (B) at 40 °C. In plastic cuvettes, adiscoloration of the cuvette wall remains, interpreted as a high affinityof the dehydrated PNIPAM for the cuvette walls.
Mentions: Figure 4A shows the stability of the 10.7 nm core/20kDa PNIPAM superparamagnetic particles to the magnetic field producedby a strong permanent magnet at room temperature below the LCST; allthe individually stabilized particles remain dispersed. Upon heatingto 40 °C (above the LCST of 32 °C), the core–shellparticles weakly aggregate as shown by the DLS measurements above.The aggregates in the turbid particle dispersion can then be attractedby the same magnetic field (Figure 4B). The almost complete extraction of nanoparticlesobserved at moderate heating with a standard magnet contrasts to theincomplete withdrawal demonstrated earlier by nanoparticles with aphysisorbed block copolymer PNIPAM shell architecture11 or by polydisperse PNIPAM-grafted nanoparticles.19 Upon cooling below the LCST, the brown precipitatewas redissolved by gentle shaking, demonstrating the reversibilityof the process and the stability of the core–shell nanoparticlesagainst thermal stress.

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.


Related in: MedlinePlus