Magnetomicelles: Nanostructures from Magnetic Nanoparticles and Cross- Linked Amphiphilic Block Copolymers Olivier Nguon Worth Reading Paper: October 2005 UW CHEM 7530*/750 February 14 th, 2006

References NANOLETTERS 2005, Vol. 5, No. 10, 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 targeting Tags for biomolecular sensors Biomolecule separation and purification In vivo imaging Stability and surface functionality of magnetic nanostructures

Synthesis Nanoparticles γ-Fe : Thermal decomposition of Fe(CO) 5 in hydrocarbon solvent Further oxidation using (CH 3 ) 3 NO TEM image of 10.9 nm γ-Fe 2 O 3 nanoparticles

Synthesis (next) Amphiphilic block copolymer: poly(styrene 250 -block-acrylic acid 13 ) Or PS 250 -b-PAA 13 Atom-transfer radical polymerization 1 Dissolved in DMF __________________________________________________________ 1. Kang, Y.; Taton, T. A. Angew. Chem., Int. Ed. 2005, 44,

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

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