Water-Soluble Superparamagnetic Magnetite Nanoparticles with Biocompatible Coating for Enhanced Magnetic Resonance Imaging

Abstract

Ultrasmall superparamagnetic Fe(3)O(4) nanoparticles (USIRONs) were synthesized by a novel, easily scalable chemical reduction of colloidal iron hydroxide under hydrothermal conditions. The average crystallite size (5.1 ± 0.5 nm) and good crystallinity of the samples were supported by HR-TEM analysis and the saturation magnetization value (47 emu g(-1)). Vitamin C, used as a chemical reducing agent, also served as a capping agent in the oxidized form (dehydroascorbic acid, DHAA) to impart nanoparticles with exceptional solubility and stability in water, PBS buffer, and cell culture medium. Detailed physicochemical analysis of the USIRON suspensions provided insight into the magnetic ordering phenomena within the colloid, arising from the formation of uniform clusters displaying a hydrodynamic size of 41 nm. Phantom experiments on the contrast agent (clinical 3 T MRI scanner) revealed an enhanced r(2)/r(1) ratio of 36.4 (r(1)= 5 s(-1) mM(-1) and r(2)= 182 s(-1) mM(-1)) when compared to the clinically approved agents. The potential of the DHAA-Fe(3)O(4) nanoparticles as negative contrast agents for MRI with optimal hydrodynamic size for extended blood circulation times was confirmed by strong contrast observed in T(2)- and T(2)*-weighted images. The cell tests performed with primary human immune-competent cells confirmed the excellent biocompatibility of USIRONs.

Water-dispersible ascorbic-acid-coated magnetite nanoparticles for contrast enhancement in MRI

“…The characteristic absorption peak at 1,750 cm -1 in the spectra of ascorbic acid is due to stretching vibrations of the C=O of the five-membered lactone ring and this band is disappeared after coating on the nanoparticles. The C=C stretching band shows a shift from 1,665 to 1,635 cm -1 after coating on the nanoparticles (Xiao et al 2011). The absence of the C=O band and the shift of the C=C band by *30 cm -1 after coating indicate that the C=O group of the lactone ring essentially binds on the surface of the nanoparticles.…”

Magnetite (Fe3O4) Nanoparticles Alleviate Growth Inhibition and Oxidative Stress Caused by Heavy Metals in Young Seedlings of Cucumber (Cucumis Sativus L)

“…We chose 2000 mg/L concentration as the upper limit in this study because, according to the US EPA [26] guidelines, this level could be regarded as the phytotoxicity level on tested plant species if there is no negative effect on root growth under such a high concentration. The accumulation of metals and the oxidative stress were investigated only at 1 mM of the selected metals with or without nano-Fe 3 O 4 (2000mg/L).…”

Multifunctional Properties of Cyanate Ester Composites with SiO2 Coated Fe3O4 Fillers

“…25,26 However, the coercive field, H C , and the remanent magnetization, M R , of these submicrometer spheres are nearly zero, which indicates typical superparamagnetic behavior. 27,28 The demonstrated superparamagnetism in the spheres is attributed to the fine grain size (∼10 to 20 nm), which is lower than the critical size (∼30 Figure 6 shows micrographs of fracture surfaces of BECy−matrix composites with 10 and 20 vol % loadings of Fe 3 O 4 −SiO 2 core−shell spheres. Very few fine air bubbles (in dark contrast with size less than 1 μm) can be seen.…”