The aim of the project is to synthesize iron oxide magnetic nanoparticles (MNPs) in situ within the core of arborescent copolymer micelles consisting of polystyrene-g-poly(2-vinylpyrydine) (PS-g-P2VP). These unimolecular micelles appear ideal as templates for the synthesis of inorganic NPs with a pre-determined particle shape and size distribution. Colloidal stability and stealth properties, enabling their in vivo applications, will be provided by a hydrophilic block copolymer through polyion complexation with the P2VP grafts. The potential application of these colloidal nanoparticles micelles in inducing cell hyperthermia and as contrast agents for magnetic resonance imaging, as well as their biocompatibility will be evaluated.The stabilizing block copolymer poly(acrylic acid)-b-poly(2-hydroxyethyl acrylate) (PAA-b-PHEA) was synthesized by atom transfer radical polymerization (ATRP) with good control over molecular weight (Mn ~7, 18 and 30kDa, � < 1.16). Particles with a hydrodynamic diameter in the 50-200 nm size range (PdI < 0.18) in buffer (pH 7) can be readily obtained and tuned through modification of the PAA-b-PHEA chain length, which was also used to balance the contribution of steric and hydrophilic stability induced by PHEA versus electrostatic stability provided by PAA. While maintaining the length of one block, decreasing the length of PAA or increasing the length of PHEA increases particle stability. These observations were attributed to a reduced particle flocculation, even when complexes with less negative zeta-potentials were formed.The synthesis of iron oxide MNPs, either by co-precipitation or in situ oxidation/reduction, required particle stability under basic conditions. As compared to the naked arborescent copolymer, the complex particle displayed a good templating potential, yielding stable, water-soluble micelles loaded with iron oxide. Further studies will include improvement of the polymer templating effect and maximization of particle magnetization.

Magnetic micelles as therapy and diagnostic agents

248th National Meeting (2014)

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