A new class of cubic SPIONs as a dual-mode T1 and T2 contrast agent for MRI

Abstract

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used as a robust negative contrast agent on conventional MRI. In this study, we (a) synthesized a new class of cubic SPIONs as a dual-mode contrast agent in MRI and (b) showed the in-vivo feasibility of these nanaoparticles as a simultaneous positive and negative contrast agent. Relaxation properties and contrast enhancement analysis of the synthesized SPIONs with two different shapes (cubic vs. spherical) and three different sizes 7nm, 11nm, and 14nm were investigated to evaluate contrast enhancement in-vitro. In-vivo MRI experiments were performed on a 3T MR scanner, where a healthy anesthetized rat was imaged before, and from 20 to 80min after intravenous injection of 1mg/kg of contrast agent. Representative transmission electron microscopy (TEM) images of the synthesized nanoparticles reveal that the particles are well dispersed in a solvent and do not aggregate. The in-vitro relaxivity and contrast enhancement analysis show that, among all six SPIONs tested, 11-nm cubic SPIONs possess optimal molar relaxivities and contrast enhancement values, which can shorten the spin-lattice and spin-spin relaxation times, simultaneously. No noticeable toxicity is observed during in-vitro cytotoxicity analysis. In-vivo T-and T-weighted acquisitions at 60-min post-injection of 11-nm cubic SPIONs result in 64% and 48% contrast enhancement on the T-and T-weighted images, respectively. By controlling the shape and size of SPIONs, we have introduced a new class of cubic SPIONs as a synergistic (dual-mode) MRI contrast agent. 11-nm cubic SPIONs with smaller size and high positive and negative contrast enhancements were selected as a promising candidate for dual-mode contrast agent. Our proof-of-concept MRI experiments on rat demonstrate the in-vivo dual-mode contrast enhancement feasibility of these nanoparticles.

Iron Oxide Nanoparticles: An Alternative for Positive Contrast in Magnetic Resonance Imaging

“…In addition, typical gradient sequences such as fast low angle shot (FLASH) acquisition yielded strong negative vessel contrast, resulting in a higher number of discernible vessel branches. Moreover, in 2018 Alipour et al [82] developed 11 nm silica coated cubic SPIONs as a dual-mode contrast agent for T 1 and T 2 MRI. In vivo investigations on a 3 T MRI scanner demonstrated both positive and negative contrast enhancement 70 min post intravenous injection in healthy rat models.…”

Development of hollow ferrogadolinium nanonetworks for dual-modal MRI guided cancer chemotherapy

“…[6][7][8][9] However, the inherent limitations of single mode CAs are oen criticized, thus rendering dualmodal MRI CAs as more acceptable because the synergistic combination of T 1 -and T 2 -weighted MRI can provide more comprehensive imaging information, increase the diagnostic accuracy, and improve the overall prognosis of patients. 10,11 In the study of dual-modal MRI CAs, most attention has been paid to ferrogadolinium nanocomposites because Gd-and Febased compounds are commonly used as T 1 and T 2 CAs, respectively. 12,13 It is worth noting that as T 1 CAs are directly in contact with the magnetic core and located within the magnetic eld generated by the magnetic core and opposite to the external magnetic eld, T 2 CAs can severely perturb T 1 imaging.…”

Stimuli-Responsive Materials for Tissue Engineering and Drug Delivery

“…Another important application of superparamagnetic MNPs is to thermally conduct the ablation of pathological cells, or to induce the thermal release of drugs within composites materials, due to the capacity of heating up when they are in proximity of an alternating magnetic field [199,224,225]. Furthermore, some MNPs, in particular SPIONs, are widely used in magnetic resonance imaging (MRI) as contrast agents [216,226,227] or for the treatment of infectious diseases, due their intrinsic activity as antimicrobial agents [228].…”