Aggregation of superparamagnetic iron oxide nanoparticles in dilute aqueous dispersions: Effect of coating by double-hydrophilic block polyelectrolyte

Multifunctional Polymeric Platform of Magnetic Ferrite Colloidal Superparticles for Luminescence, Imaging, and Hyperthermia Applications

“…Self-assembly organization of single nanoparticles can result in enhanced magnetic performance emerging from the interactions between neighboring particles. − An effective way to stabilize MNPs in water, especially hydrophobic ones, and create MSPs is their encapsulation in polymeric nanostructures. A variety of polymers with different architectures like block − or hydrophobically modified water-soluble (HMWSP) − copolymers have been utilized for the dispersion of hydrophobic MNPs in water.…”

Stabilization of aqueous dispersions of poly(methacrylic acid)-coated iron oxide nanoparticles by double hydrophilic block polyelectrolyte poly(ethylene oxide)-block-poly(N-methyl-2-vinylpyridinium iodide)

“…2) showing that the distributions of hydrodynamic radii of the aggregates are very broad which results also in the strongly q-dependent apparent diffusion coefficients. It is worth mentioning that values of the exponent close to 1 were reported earlier for SPION aggregates in aqueous dispersions [20,26] and it was suggested that the low mass fractal dimensions of the aggregates in such systems can be caused also by the formation of wormlike structures due to dipolar magnetic interactions between small SPION clusters. This hypothesis, however, is not supported by the results of TEM or AFM measurements.…”

“…5 indicate that the tendency of SPIONs to form clusters is suppressed by adding a PEO-QP2VP layer to PMAA@SPIONs. It is noteworthy that our previous study [20] …”

“…Block copolymers one block of which binds to NP surface and the other forms the hydrated protective corona which provides the steric stabilization represent a class of such spacers [18,19]. NPs coated by a charged agent can be stabilized by an additional layer of a double hydrophilic block polyelectrolyte (DHBP) consisting of a neutral hydrophilic block and an oppositely charged polyelectrolyte block [20]. In this article, we use a combination of scattering (SAXS, light scattering, small-angle light scattering) and microscopy (TEM, AFM) techniques to study the size and structure of the aggregates formed in PMAA@SPIONs aqueous dispersions and the influence of the secondary coating of PMAA@SPIONs by cationic DHBP poly(ethylene oxide)-block-poly(N-methyl-2-vinylpyridinium iodide) (PEO-QP2VP) on the aggregation, including both the cluster formation at the nanometer scale and the overall size of the aggregates in the range of micrometers.…”

Stable, polymer-directed and SPION-nucleated magnetic amphiphilic block copolymer nanoprecipitates with readily reversible assembly in magnetic fields

“…9 Small molecule stabilising agents for SPIONs are known to desorb with decreasing concentration and lead to dilutiondriven aggregation, whereas charged block-copolymer electrolytes have been reported to provide stabilisation to oleatecoated SPIONs in dilute dispersions and mediate the density of large aggregates on the micron-scale. 10 Our research has focused on various polymers of complex architecture and their nanoprecipitation to yield monodisperse polymer nanoparticles with variable surface chemistries. [11][12][13] In recent years, we have observed that branched polymer nanoparticles can yield highly stable nanoprecipitates and the incorporation of polyethylene glycol (PEG)-derived initiators, within their controlled radical synthesis, leads to excellent stability under various environmental conditions.…”