Magnetomicelles: Nanostructures from Magnetic

Nanoparticles and Cross-Linked

Amphiphilic Block Copolymers

Olivier NguonWorth Reading Paper: October 2005

UW CHEM 7530*/750February 14th, 2006

References

NANOLETTERS 2005, Vol. 5, No. 10, 1987-91

Byeong-Su Kim, Jiao-Ming Qiu, Jian-Ping Wang, and T. Andrew Taton*

Department of Chemistry and Department of Electrical and Computer Engineering,

University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455

Magnetomicelles

Cross-linked, amphiphilic block-copolymer (micelles)

Encapsulate superparamagnetic iron oxide nanoparticles (magnetic)

Interests: magnetic particles

Carriers for magnetic drug targetingTags for biomolecular sensorsBiomolecule separation and purificationIn vivo imaging

Stability and surface functionality of magnetic nanostructures

Synthesis

Nanoparticles γ-Fe203:

Thermal decomposition of Fe(CO)5 in hydrocarbon solvent

Further oxidation using (CH3)3NO

TEM image of 10.9 nm

γ-Fe2O3 nanoparticles

Synthesis (next)

Amphiphilic block copolymer:

poly(styrene250-block-acrylic acid13)

Or PS250-b-PAA13

Atom-transfer radical polymerization1

Dissolved in DMF__________________________________________________________

1. Kang, Y.; Taton, T. A. Angew. Chem., Int. Ed. 2005, 44, 409-412.

Synthesis (next)

Nanoparticles in THF Added to polymer in DMF in defined ratio Water added gradually to desolvate Cross-linker added: 2,2’-(ethylenedioxy)bis(ethylamine)

Experimental procedure for magnetomicelles preparation

Control of properties

Average number of encapsulated particles per micelle (Nave):

Controlled by varying relative concentrations of nanoparticles and polymer

Increased particle concentration Increased numbers of nanoparticles incorporated

Encapsulation tests

Aqueous HCl (pH 2), a known etchant for iron oxide

TEM analysis: particles not affected

Suspensions stable to a variety of biological buffer (wide pH range pH 2-11)

Achievements and limitation

Encapsulation of magnetic nanoparticles within amphiphilic block-copolymer micelles

Control of magnetic properties by varying the relative concentrations of the magnetic nanoparticles

Hydrophilic shell can be functionalized chemically

Not able to encapsulate one single particule

Future developments

Other inorganic nanostructure materials

Different shapes

Biotechnological, micro- and nanomaterials applications

Thank You !!

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