Synthesis of Multifunctional Magnetic NanoFlakes for Magnetic Resonance Imaging, Hyperthermia, and Targeting.

Abstract

Iron oxide nanoparticles (IOs) are intrinsically theranostic agents that could be used for magnetic resonance imaging (MRI) and local hyperthermia or tissue thermal ablation. Yet, effective hyperthermia and high MR contrast have not been demonstrated within the same nanoparticle configuration. Here, magnetic nanoconstructs are obtained by confining multiple, ∼ 20 nm nanocubes (NCs) within a deoxy-chitosan core. The resulting nanoconstructs—magnetic nanoflakes (MNFs)—exhibit a hydrodynamic diameter of 156 ± 3.6 nm, with a polydispersity index of ∼0.2, and are stable in PBS up to 7 days. Upon exposure to an alternating magnetic field of 512 kHz and 10 kA m–1, MNFs provide a specific absorption rate (SAR) of ∼75 W gFe–1, which is 4–15 times larger than that measured for conventional IOs. Moreover, the same nanoconstructs provide a remarkably high transverse relaxivity of ∼500 (mM s)−1, at 1.41T. MNFs represent a first step toward the realization of nanoconstructs with superior relaxometric and ablation properties for more effective theranostics.

Multicomponent, peptide-targeted glycol chitosan nanoparticles containing ferrimagnetic iron oxide nanocubes for bladder cancer multimodal imaging

“…While we did not optimize relaxivities in this paper, Hyeon's group demonstrated that NCs can potentially provide transversal relaxivities r 2 , as high as 761 mM . 10 This result is about fivefold better than commercialized iron oxide nanospheres, Feridex, 10,13 indicating that NCs have potential advantages over nanospheres.…”

“…13,33 The only limitation is that ferrimagnetic iron oxide NCs have size-dependent coercivity as the particle size increases while SPIOs are zero-coercive. 13,33 Therefore, when we engineer the iron oxide NCs with proper stabilizers, such as amphipathic polymers, it is possible to satisfy both high relaxivity and specific targeting. In this study, we demonstrated a good biodistribution of the nanoparticles (NPs) for bladder cancer imaging using 22 nm iron oxide NCs.…”

“…The ferrimagnetic iron oxide NCs show high MRI contrast and hyperthermia. 10,13 However, ferrimagnetic iron oxide NCs are not easy to use in biological applications due to magnetic memory after exposure to an external magnetic field. Magnetic memory leads the iron oxide particles to cluster quickly, which could boost precipitation of the particles in biological conditions.…”

Amperometric magnetobiosensors using poly(dopamine)-modified Fe3O4 magnetic nanoparticles for the detection of phenolic compounds

“…Magnetic nanoparticles (MNPs) have gained a lot of attention in biomedical and industrial applications due to their biocompatibility, easy synthesis and ability of surface modification [18][19][20][21][22][23] . Moreover, they provide a large surface area for attachment of biorecognition elements and can then be easily separated from the liquid phase by a magnet, and spread immediately to zoom out which results highly appropriate in sensor and biosensor applications 16,17,22 .…”

Means to increase the therapeutic efficiency of magnetic heating of tumors

“…[5]). Nevertheless, and apart from the occurrence of susceptibility artifacts at the tumor region via MRI that results from the use of high amounts of iron to obtain the appropriate local temperatures, MRI and magnetic hyperthermia are based on different and even counteracting parameters, which makes it challenging to combine them.…”