Highly water-dispersible PEG surface modified ultra small superparamagnetic iron oxide nanoparticles useful for target-specific biomedical applications

Abstract

For the application of superparamagnetic iron oxide nanoparticles in biomedical fields for target-specific purposes, they should be ultra small in diameter. We developed a simple one-step synthesis of surface modified ultra small superparamagnetic iron oxide nanoparticles (USPIONs) with an average particle diameter of 1.7 nm in a polar organic solvent. Polyethylene glycol diacid (PEG) surface modified USPIONs synthesized in triethylene glycol were nearly monodisperse in diameter and highly water-dispersible. The PEG surface modified USPIONs were tested for use as magnetic resonance (MR) contrast agents. They had a low r(2)/r(1) relaxivity ratio of 3.4 (r(1) = 4.46 and r(2) = 15.01 mM(-1) s(-1)) and showed clear dose-dependent T(1) and T(2) map images, indicating that they will be useful as both target-specific T(1) and T(2) MR contrast agents due to their ultra small size.

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

“…Ultra-small superparamagnetic iron oxide nanoparticles (USPIONs) also act as T 1 contrast agents. Park et al (2008) reported the synthesis of polyethylene-glycol-capped iron oxide nanoparticles which act both as T 1 and T 2 contrast agents. The corresponding relaxivities r 1 and r 2 have been reported as 4.46 and 15.01 mM -1 s -1 in a magnetic field of 1.5 T. Blood residence time of nanoparticles is known to increase with decreasing particle size (Arruebo et al 2007) and larger particles are rapidly absorbed by the reticuloendothelial system and accumulated in the liver or spleen preventing their availability in the blood.…”

Pullulan acetate coated magnetite nanoparticles for hyper-thermia: Preparation, characterization and in vitro experiments

“…Magnetic nanoparticles with tailored surface chemistry have recently attracted a great deal of attention by virtue of their potential biomedical applications including magnetic resonance imaging (MRI) contrast enhancement [1][2][3][4], hyperthermia [5][6][7], immunoassay [8], and drug delivery [9]. Hyperthermia involves applying an alternating magnetic field of suitable frequency that produces heat dissipation through the oscillation of the internal magnetic moment of superparamagnetic particles.…”

Gd(III) doping effect on magnetization and water proton relaxivities in ultra small iron oxide nanoparticles

“…These are consistent with expectations because the d mag corresponds to the largest nanoparticle in a size distribution. As provided in Table I, net magnetizations in both samples were smaller than 6.5 and 8.4 emu/g of ultra small iron oxide nanoparticles 17 and ultra small gadolinium oxide nanoparticles, 18 respectively. Therefore, magnetization was reduced by doping Gd(III) into ultra small iron oxide nanoparticles.…”

“…Figure 9 clearly shows Gd(III) doping effect on magnetization and r 1 and r 2 values. That is, magnetizations and r 1 and r 2 values of two samples are smaller than those of ultra small iron oxide nanoparticles 17 and ultra small gadolinium oxide nanoparticles. 18 As investigated by others, magnetic moment of Gd(III) is anti-parallel to net magnetic moment of Fe(III)/Fe(II) in oxides.…”

“…17 In this work we additionally doped tiny mole percents of Gd(III) into ultra small iron oxide nanoparticles. Core particle diameter, crystal structure, surface composition, surface coating, magnetic properties, r 1 and …”