Synthesis of Iron Oxide Nanoclusters with Enhanced Magnetization and Their Applications in Pulsed Magneto-Motive Ultrasound Imaging

Abstract

We report here a facile synthetic approach for preparing water-soluble Fe 3 O 4 nanoparticle (NP) clusters with tunable size distribution and magnetic properties. The primary NP sizes were controlled by tuning the nucleation and growth rates with temperature and ligand concentration while the nanocluster sizes were manipulated by controlling interparticle interactions. We have investigated the size control of clusters as well as individual primary NPs via dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM). Superconducting quantum interference device (SQUID) was used to measure the magnetic properties of Fe 3 O 4 NP for determining the e®ect of size distribution at room temperature. These water dispersible NP clusters can be utilized in various biomedical applications. In this study, we demonstrated the application of synthesized nanoclusters to enhance imaging contrast a novel ultrasound-based imaging modality, pulsed magneto-motive ultrasound (pMMUS) imaging. Our results indicated that by using the NP clusters with enhanced magnetic properties, the pMMUS signal increased signi¯cantly which is an essential requirement for further development of in vivo pMMUS imaging.

Magnetic Nanoparticle Systems for Nanomedicine—A Materials Science Perspective

“…While keeping the superparamagnetic behavior, the synthesis of multicore particles proved to be a promising solution for magnetics based imaging, therapeutics, and sensing to improve the manifold magnetic response of particles [40,[52][53][54][55][56]. Magnetic nanoparticle clusters embedded in a polymer shell, to sum the magnetic moments of each nanoparticle, were made applying in situ coprecipitation by using gels as microreactors [57,58], and also by strongly polar solvent induced destabilization of a ferrofluid [59].…”

“…Bio-ferrofluids having multi-core particles [40,52,53,[163][164][165][166] demonstrated an increasing interest for the biomedical area during the last years. The higher particle diameter, still guaranteeing a stable suspension, but without magnetized clumps of particles that are caused by remanence, allows for a more effective collection of the particles by the liver.…”

“…Indeed, these multicore composites of sizes well above 20 nm show superparamagnetic properties at room temperature (300 K), while at very low temperature (~2 K) clusters of similar sizes would exhibit typical ferromagnetic hysteresis loops [38]. The particles' magnetic moment is more relevant than mass magnetization in order to assess the magnetic targeting/fixing applicability of magnetic particles [19,39,40].…”

Hybrid Nanoparticles of Citrate-Coated Manganese Ferrite and Gold Nanorods in Magneto-Optical Imaging and Thermal Therapy

“…The induced displacement of a phantom labeled with 0.4 wt% Ci-MnFe 2 O 4 _0.07 wt% CTAB-GNRs hybrid NPs was significantly greater at around 30.6 ± 4.16 μm than that of 0.4 wt% Ci-MnFe 2 O 4 _0.04 wt% CTAB-GNRs (19.42 ± 2.9 μm) and the sample labeled with 0.4 wt% Ci-MnFe 2 O 4 (8 ± 1 μm). Mehrmohammadi and Yoon et al [ 62 , 63 ] also found that using small nanoclusters of MNPs with a size of 55 nm resulted in higher displacements for pulsed MMUS than using individual MNPs. Hence, a similar outcome was observed in our work by generating nanoclusters, which agrees with Mehrmohammadi and Yoon et al [ 62 , 63 ].…”

“…Mehrmohammadi and Yoon et al [ 62 , 63 ] also found that using small nanoclusters of MNPs with a size of 55 nm resulted in higher displacements for pulsed MMUS than using individual MNPs. Hence, a similar outcome was observed in our work by generating nanoclusters, which agrees with Mehrmohammadi and Yoon et al [ 62 , 63 ].…”