Towards the Rational Design of MRI Contrast Agents: Electron Spin Relaxation Is Largely Unaffected by the Coordination Geometry of Gadolinium(III)–DOTA‐Type Complexes

Abstract

Electron-spin relaxation is one of the determining factors in the efficacy of MRI contrast agents. Of all the parameters involved in determining relaxivity it remains the least well understood, particularly as it relates to the structure of the complex. One of the reasons for the poor understanding of electronspin relaxation is that it is closely related to the ligand-field parameters of the Gd 3+ ion that forms the basis of MRI contrast agents and these complexes generally exhibit a structural isomerism that inherently complicates the study of electron spin relaxation. We have recently shown that two DOTAtype ligands could be synthesised that, when coordinated to Gd 3+ , would adopt well defined coordination geometries and are not subject to the problems of intramolecular motion of other complexes. The EPR properties of these two chelates were studied and the results examined with theory to probe their electron-spin relaxation properties. Borel et al.

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

“…The apparent maxima of the spectrum of both complexes is at approximately 30800 cm -1 (325 nm), which is consistent with the singlet-state energies of other pyridine-containing complexes. [29] The addition of Zn [30] For instance, it has been shown that the nature and polarizability of the group occupying a position on or close to the principal axis of the complex affects the relative intensity of the 5 D 0 Ǟ 7 F 2 transition. [31] The more polarizable the axial donor atom is, the greater the relative The hydration states of the EuL1 and EuL2 complexes were studied by comparison of their luminescence lifetimes in H 2 O and D 2 O.…”

Ultra small Gd2O3 nanoparticles: Absorption and emission properties

“…MRI is a noninvasive imaging technique used for diagnosis of diseases [1][2][3][4][5][6][7][8][9][10][11][12][13]. When a biological sample is placed under an MRI scanner, the magnetic field perturbs the equilibrium spin state of the sample [2,4,10,13].…”

Biodistribution, kinetics, and biological fate of SPION microbubbles in the rat

“…[13][14][15][16][17][18][19][20] For instance, SPION nanoclusters have been used as a negative contrast agent in liver and heart imaging, 21 and SPION-folate-poly(ethylene glycol) has been used for lung cancer imaging. 22 The microbubbles used in this investigation represent a novel microdevice consisting of poly(vinyl alcohol) (PVA) containing SPION in between the shells.…”