An Efficient and Highly Versatile Synthetic Route to Prepare Iron Oxide Nanoparticles/Nanocomposites with Tunable Morphologies

Abstract

We report a versatile synthetic method for the in situ self-assembly of magnetic-nanoparticle-functionalized polymeric nanomorphologies, including spherical micelles and rod-like and worm-like micelles and vesicles. Poly(oligoethylene glycol methacrylate)-block-(methacrylic acid)-block-poly(styrene) (POEGMA-b-PMAA-b-PST) triblock copolymer chains were simultaneously propagated and self-assembled via a polymerization-induced self-assembly (PISA) approach. Subsequently, the carboxylic acid groups in the copolymers were used to complex an iron ion (Fe(II)/Fe(III)) mixture. Iron oxide nanoparticles were then formed in the central block, within the polymeric nanoparticles, via alkaline coprecipitation of the iron(II) and (III) salts. Nanoparticle morphologies, particle sizes, molecular weights, and chemical structures were then characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), size exclusion chromatography (SEC), and (1)H NMR measurements. TEM micrographs showed that the average size of the magnetic nanoparticles was ∼7 nm at the hydrophobic/hydrophilic nexus contained within the nanoparticles. In addition, XRD was used to confirm the formation of iron oxide nanoparticles. Importantly, the polymeric nanoparticle morphologies were not affected by the coprecipitation of the magnetic nanoparticles. The hybrid nanoparticles were then evaluated as negative MRI contrast agents, displaying remarkably high transverse relaxivities (r2, greater than 550 mM(-1) s(-1) at 9.4 T); a result, that we hypothesize, ensues from iron oxide nanoparticle clustering at the hydrophobic-hydrophilic interface. This simple synthetic procedure is highly versatile and produces nanocarriers of tunable size and shape with high efficacy as MRI contrast agents and potential utility as theranostic delivery vectors.

Semi‐Fluorinated Methacrylates: A Class of Versatile Monomers for Polymerization‐Induced Self‐Assembly

“…Compared with the traditional self‐assembly protocols, PISA allows preparing the desired polymer assemblies via readily adjusting the polymer‐related parameters, including hydrophilic/hydrophobic ratio and polymer concentration. Hence, PISA has been extensively studied to understand the self‐assembly mechanism of amphiphilic copolymers and to develop new drug carriers, dynamic gels, Pickering emulsifiers, etc …”

Photoinitiated Polymerization‐Induced Self‐Assembly of Glycidyl Methacrylate for the Synthesis of Epoxy‐Functionalized Block Copolymer Nano‐Objects

“…Deposition of inorganic nanoparticles onto polymer nano‐objects is an attractive strategy to prepare inorganic/organic materials . The primary amine group on the cross‐linked PGMA nano‐object can be utilized to attach heavy metal nanoparticles.…”

Reactive and Functional Nanoobjects by Polymerization‐Induced Self‐Assembly

“…A related system was reported by Davis, Boyer, and coworkers for the synthesis of iron oxide nanoparticles . In that case, POEGMA‐ b ‐PMAA‐ b ‐PS triblock copolymer nanoobjects of various morphologies were to bind Fe II/III salts in water.…”