Synthesis of Nonspherical Superparamagnetic Particles: In Situ Coprecipitation of Magnetic Nanoparticles in Microgels Prepared by Stop-Flow Lithography

Abstract

We present the synthesis of nonspherical magnetic microparticles with multiple functionalities, shapes, and chemistries. Particle synthesis was performed in two steps: polymeric microparticles functionalized homogenously with carboxyl groups were generated using stop-flow lithography, and then in situ coprecipitation was used to grow magnetic nanoparticles at these carboxyl sites. With successive growth of magnetic nanoparticles, we obtained polymeric particles with saturation magnetizations of up to 42 emu/g microparticle. The growth in the magnetic nanoparticle mean size and polydispersity was determined from the magnetization curves obtained following each growth cycle; nanoparticle sizes were limited by the physical constraint of the effective mesh within the hosting gel microparticle. Particles with spatially segregated domains of varying magnetic properties (e.g., Janus particles, particles with step changes in magnetite concentration, etc.) can be synthesized readily using this approach.

Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

“…Consequently, diverse synthetic approaches-including coprecipitation [6], hydrothermal-solvothermal [7], sol-gel [8], and thermal decomposition [9]-have been developed to engineer NP features accordingly, always striving towards the common goal of obtaining monodisperse NPs, easily and finely tuning their size and shape in a most reproducible way.…”

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Magnetic microgels for drug targeting applications: Physical–chemical properties and cytotoxicity evaluation

“…The high magnetic moment of the functionalized carriers is among the most important requirements for successful applications in biomedicine, in particular for magnetic targeting [9]. Magnetic nanoparticle clusters in a polymer shell, summing up the magnetic moments of individual nanoparticles, were obtained by in situ coprecipitation of magnetic nanoparticles in microgels as microreactors [10,11] and also by strongly polar solvent induced destabilization of a ferrofluid [12]. The controlled clusterization of magnetic nanoparticles, followed by encapsulation of the densely packed magnetic core in a polymer shell proved to be a facile and reproducible procedure when using the well-established ferrofluid technology and oil-in-water miniemulsion procedure [13,14,15].…”