Superparamagnetic Contrast Agents

Corot, Claire; Port, Marc; Guilbert, Irène; Robert, Philippe; Robic, Caroline; Raynaud, Jean‐Sébastien; Prigent, Philippe; Dencausse, Anne; Idée, Jean‐Marc

doi:10.1201/9781420004090-4

Cited by 11 publications

(1 citation statement)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For transverse relaxation which relates to their efficacy as T 2 contrast agents, noting the large confidence intervals, the r 2 and r 2 * relaxivities of the three SPIONs are very large, and are much higher than (i) those measured in other studies at 7 T, for example, SPIONs of 12 nm with r 1 =1.2 mM −1 s −1 and r 2 =247 mM −1 s −1 , and SPIONs with D H ca. 29 nm coated with PEG afforded T 2contrast abilities with r 2 =345 mM −1 s −1 [61], and (ii) some of the clinically approved MRI probes Ferumoxides® (r 1 =1.8 mM −1 s −1 and r 2 =132 mM −1 s −1 ) and Ferucarbotran A® (r 1 =1.6 mM −1 s −1 and r 2 =205 mM −1 s −1 ) [70].…”

Section: Mri Studiesmentioning

confidence: 99%

Surface engineering of SPIONs: role of phosphonate ligand multivalency in tailoring their efficacy

Lam¹,

Avti²,

Pouliot³

et al. 2016

Nanotechnology

View full text Add to dashboard Cite

We report the design of scaffolds containing mono-, bis-, and tris-phosphonate coordinating groups, and a polyethylene glycol chain, for stabilizing superparamagnetic iron oxide nanoparticles (SPIONs), using simple and versatile chemistry. We demonstrate that the number of anchoring phosphonate sites on the ligand influence the colloidal stability, magnetic and biological properties of SPIONs, and the latter do not solely depend on attaching moieties that can enhance their aqueous dispersion. These parameters can be tailored by the number of conjugation sites on the ligand, as evidenced from dynamic light scattering at various salt concentrations, magnetic relaxivities and cell viability studies.

show abstract

Section: Mri Studiesmentioning

confidence: 99%

Surface engineering of SPIONs: role of phosphonate ligand multivalency in tailoring their efficacy

Lam¹,

Avti²,

Pouliot³

et al. 2016

Nanotechnology

View full text Add to dashboard Cite

show abstract

Nano assembly and encapsulation; a versatile platform for slowing the rotation of polyanionic Gd³⁺‐based MRI contrast agents

Farashishiko

Chacón

Blackburn

et al. 2015

Contrast Media & Molecular

View full text Add to dashboard Cite

Encapsulating discrete Gd3+ chelates in nano-assembled capsules (NACs) is a simple and effective method of preparing an MRI contrast agent capable of delivering a large payload of high relaxivity imaging agent. The preparation of contrast agent containing NACs had previously focussed preparations incorporating GdDOTP5− into the internal aggregate. In this report we demonstrate that other Gd3+ chelates bearing overall charges as low as 2- can also be used to prepare NACs. This discovery opens up the possibility of using Gd3+ chelates that have inner-sphere water molecules that could further increase the relaxivity enhancement associated with the long τR that arises from encapsulation. However, encapsulation of the q = 1 chelate GdDTPA2− did not give rise to a significant increase in relaxivity relative to encapsulation of the outer-sphere chelate GdTTHA3−. This leads us to the conclusion that in the NAC interior proton transport is not mediated by movement of whole water molecules and the enhanced relaxivity of Gd3+ chelate encapsulated within NACs arises primarily from second sphere effects.

show abstract

Intracellular and extracellular T₁ and T₂ relaxivities of magneto‐optical nanoparticles at experimental high fields

Klug¹,

Kampf

Bloemer

et al. 2010

Magnetic Resonance in Med

View full text Add to dashboard Cite

This study reports the T 1 and T 2 relaxation rates of rhodamine-labeled anionic magnetic nanoparticles determined at 7, 11.7, and 17.6 T both in solution and after cellular internalization. Therefore cells were incubated with rhodamine-labeled anionic magnetic nanoparticles and were prepared at decreasing concentrations. Additionally, rhodamine-labeled anionic magnetic nanoparticles in solution were used for extracellular measurements. T 1 and T 2 were determined at 7, 11.7, and 17.6 T. T 1 times were determined with an inversionrecovery snapshot-flash sequence. T 2 times were obtained from a multispin-echo sequence. Inductively coupled plasmamass spectrometry was used to determine the iron content in all samples, and r 1 and r 2 were subsequently calculated. The results were then compared with cells labeled with AMI-25 and VSOP C-200. In solution, the r 1 and r 2 of rhodamine-labeled anionic magnetic nanoparticles were 4.78/379 (7 T), 3.28/389 (11.7 T), and 2.00/354 (17.6 T). In cells, the r 1 and r 2 were 0.21/56 (7 T), 0.19/37 (11.7 T), and 0.1/23 (17.6 T). This corresponded to an 11-to 23-fold decrease in r 1 and an 8-to 15-fold decrease in r 2 . A decrease in r 1 was observed for AMI-25 and VSOP C-200. AMI-25 and VSOP exhibited a 2-to 8-fold decrease in r 2 . In conclusion, cellular internalization of iron oxide nanoparticles strongly decreased their T 1 and T 2 potency. Magn Reson Med 64:1607-1615, 2010. V C 2010 Wiley-Liss, Inc.Key words: iron oxide nanoparticles; relaxivities; cellular internalization; high fieldThe unique soft-tissue contrast achieved by magnetic resonance imaging (MRI) originates from the variations of longitudinal (T 1 ) and transversal (T 2 /T 2 *) proton relaxation rates between different tissues. T 1 -and T 2 -shortening contrast agents are commonly used to enhance contrast. T 1 -shortening results in enhanced signal and/or faster imaging due to a higher value of available longitudinal magnetization for repetitive excitations. Because of faster spin relaxation, T 2 -shortening results in less signal but even higher contrast. As all contrast agents lower T 1 and T 2 , the ratio of the molar relaxivities (r 1 /r 2 ) is commonly used to describe their features.Superparamagnetic iron oxides particles (SPIOs) mainly shorten T 2 /T 2 * (r 1 /r 2 at 0.47 T: 0.2-0.6) (1-3); therefore, they are considered as ''negative contrast'' agents. For high field strengths above 2 T, r 1 decreases to zero and r 2 approaches a constant nonzero value. This results in a significant shift of the r 1 /r 2 ratio to lower values (r 1 /r 2 at 7 T: 0.01-0.1) (3-6). Therefore, at field strengths above 7 T, T 2 /T 2 *-weighted imaging sequences are commonly used for SPIO-enhanced MRI. In contrast to ''positive'' extracellular Gadolinium (Gd) chelates (r 1 /r 2 of Gd-DTPA at 0.47 T: >0.6), SPIOs remain in the healthy vasculature and are internalized by reticuloendothelial system cells after intravenous injection. Depending on their physicochemical properties, they are applied to MR-angiography, liver imaging (Ku...

show abstract

Superparamagnetic Contrast Agents

Cited by 11 publications

References 1 publication

Surface engineering of SPIONs: role of phosphonate ligand multivalency in tailoring their efficacy

Surface engineering of SPIONs: role of phosphonate ligand multivalency in tailoring their efficacy

Nano assembly and encapsulation; a versatile platform for slowing the rotation of polyanionic Gd³⁺‐based MRI contrast agents

Intracellular and extracellular T₁ and T₂ relaxivities of magneto‐optical nanoparticles at experimental high fields

Contact Info

Product

Resources

About

Superparamagnetic Contrast Agents

Cited by 11 publications

References 1 publication

Surface engineering of SPIONs: role of phosphonate ligand multivalency in tailoring their efficacy

Surface engineering of SPIONs: role of phosphonate ligand multivalency in tailoring their efficacy

Nano assembly and encapsulation; a versatile platform for slowing the rotation of polyanionic Gd3+‐based MRI contrast agents

Intracellular and extracellular T1 and T2 relaxivities of magneto‐optical nanoparticles at experimental high fields

Contact Info

Product

Resources

About

Nano assembly and encapsulation; a versatile platform for slowing the rotation of polyanionic Gd³⁺‐based MRI contrast agents

Intracellular and extracellular T₁ and T₂ relaxivities of magneto‐optical nanoparticles at experimental high fields