The design and utility of polymer-stabilized iron-oxide nanoparticles for nanomedicine applications

Abstract

Iron-oxide nanoparticles (IONPs) represent a significant class of inorganic nanomaterial that is contributing to the current revolution in nanomedicine [1][2]. Their unique physical properties, including high surface area to volume ratios and superparamagnetism, confer useful attributes for medical applications such as magnetic resonance imaging (MRI), drug and gene delivery, tissue engineering and bioseparation [3].Two distinct classes of superparamagnetic IONP-based materials are currently used for medical applications: superparamagnetic iron-oxide (SPIO) nanoparticles with a mean particle diameter of 50-100 nm, and ultra-small superparamagnetic iron-oxide (USPIO) nanoparticles with a size below 50 nm. Th ese two classes of IONPs have been studied widely for medical applications, particularly as the next (potential) generation of MRI contrast agents. Th ey are also seen as potential vectors for drug and gene delivery. Th e biodistribution of these nanoparticles can be altered by the application of an external magnetic fi eld; they also have potential applications in hyperthermia therapy as some magnetic particles can heat up under the infl uence of a localized high-frequency magnetic fi eld.Th e intent of this review is to present recent advances in the synthesis of IONPs and their subsequent stabilization in biological fluids using polymers, focusing on the current strategies used to graft polymers onto IONPs surfaces (see Figure 1) and the diff erent types of polymers used. Th e additional properties conferred by the polymers, such as targeting, eff ects on biodistribution and pharmacokinetics, are also discussed, and the main applications of IONPs are reviewed. Synthesis and properties of iron-oxide nanoparticlesSPIO and USPIO nanoparticles are the most extensively studied magnetic nanoparticles for biomedical applications as they are both biocompatible and easy to synthesize. Both are composed of ferrite nanocrystallites of magnetite (Fe 3 O 4 ) or maghemite (Fe 2 O 3 , γ). Over the last ten years, there has been an explosion of interest in these materials and this has been reflected in a large number of recent publications describing the synthesis and modifi cation of hybrid IONPs. In this review, we focus on the polymer modifi cation of the nanoparticles, and provide only minimal information on the inorganic synthesis of IONPs. For more detailed information on IONP synthesis, readers are referred to other reviews [3,4]. The design and utility of polymer-stabilized iron-oxide nanoparticles for nanomedicine applicationsCyrille Boyer 1 * , Michael R. Whittaker 1 , Volga Bulmus 2 , Jingquan Liu 1 and Thomas P. Davis 1 * University of New South Wales, AustraliaOver the past decade, the synthesis of superparamagnetic nanoparticles, especially iron-oxide nanoparticles (IONPs), has been researched intensively for many high-technology applications, including enhanced storage media, biosensing and medical applications. In medicine, IONPs are used as contrast agents in magnetic resonance imaging and in hyperthermia...

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