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

Abstract

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(styrene(250)-block-acrylic acid(13)) 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.

Enzyme Chemiluminescence Immuno Assay of Free hCGβ in Serum Based on Superparamagnetic Polymer Microbeads

“…Not like the normal polymeric beads of several hundred micrometers, these SPMP microbeads were much smaller, around 3 microns in their diameter. Because there were many 8-nm magnetite nanoparticles distributed and immobilized in the inner polymeric frameworks, our SPMP microbeads had much higher magnetite contents and higher magnetophoresis ability than those reported core-shell nanobeads [6, 7(b), [9][10][11] with only one or two single magnetic original particles as the cores. In this paper, we coupled antibody with the synthesized SPMP microbeads, and set up an enzyme chemiluminescent immuno assay (ECLIA).…”

“…The loss of the coating material and its terminal functionalities could demolish the biospecificity of these materials. Kim [10] also found that this cross-linkage was particularly well suited to protect and functionalize materials such as Fe 3 O 4 , γ-Fe 2 O 3 for which strongly binding surface ligands were not readily available, for it could fix the nanostructures topologically and these structures were stable to further synthetic transformations of surface functional groups.…”

“…Li et al [9] introduced the initiator 10-carboxydecanyl 2-bromo-2-methylthiopropanoate onto the surface of maghemite, utilized surface-initiated atom transfer radical polymerization (ATRP) to synthesize perfect polystyrene/maghemite core/shell polymeric nanobeads. Kim et al [10] synthesized composite nanostructures from magnetic nanoparticles and cross-linked amphiphilic block copolymers with magnetomicelles. Qiu et al [11] succeeded in preparing polypyrrole-Fe 3 O 4 magnetic nanocomposite by ultrasonic irradiation, and magnetic nanobeads were endowed with electric conductivity.…”

Controlled release of 5-fluorouracil and progesterone from magnetic nanoaggregates

“…Our approach follows directly from the second strategy; however, our method differs from other magnetic nanocarriers, namely by the coating surrounding the magnetic core. 12 These nanoaggregates are formed spontaneously by the selfassembly of block copolymers and beta-cyclodextrins, without the application of a crosslinker. They have the advantages of facile preparation without the use of any organic solvents, and of the lack of toxic polymer degradation products.…”

Preparation and control of the formation of single core and clustered nanoparticles for biomedical applications using a versatile amphiphilic diblock copolymer

“…Gao et al, for instance, developed an amphiphilic triblock copolymer which can be employed to coat nanoparticles via ligand exchange and make hydrophobic nanocrystals monodisperse in aqueous solution [9]. The other class comprises block copolymers which cannot undergo ligand exchange, but can self-assemble into micelles in water and encapsulate nanocrystals by the simultaneous co-precipitation method [12][13][14][15][16]. As well as single core nanoparticles, stabilized nanoparticle clusters can also be prepared and controlled using such block copolymers.…”