Magnetomicelles:  Composite Nanostructures from Magnetic Nanoparticles and Cross-Linked Amphiphilic Block Copolymers

• Published in: Nano letters 2005-10, Vol.5 (10), p.1987-1991
• Main Authors: Kim, Byeong-Su, Qiu, Jiao-Ming, Wang, Jian-Ping, Taton, T. Andrew
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Electronics; Exact sciences and technology; Microelectronic fabrication (materials and surfaces technology); Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Structure of solids and liquids; crystallography
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl0513939

We report the synthesis, characterization, and covalent surface chemistry of “magnetomicelles”, cross-linked, amphiphilic block-copolymer micelles that encapsulate superparamagnetic iron oxide nanoparticles. Because these composite nanostructures assemble spontaneously from solution by simultaneous desolvation of nanoparticle and amphiphilic poly(styrene250-block-acrylic acid13) components, explicit surface functionalization of the particles is not required, and the encapsulation method was applied to different magnetic nanoparticle sizes and compositions. TEM images of the magnetomicelles illustrated that the number of encapsulated particles could be dictated rationally by synthetic conditions. The magnetic properties of the particles were characterized by SQUID magnetometry and followed the general Langevin magnetic model for superparamagnetic materials. The micellar shells of these particles were functionalized using covalent chemistry that would not ordinarily be possible on the magnetic particle surface. As a result, this noncovalent approach provides a new route to technological applications of hydrophobic magnetic nanomaterials that lack appropriate conjugate surface chemistry.