Gadolinium complexes of macrocyclic diethylenetriamine-N-oxide pentaacetic acid-bisamide as highly stable MRI contrast agents with high relaxivity

Abstract

<p>Macrocyclic gadolinium(<sc>iii</sc>) complexes with hyphenated-amino-<italic>N</italic>-oxide (HAO) type ligand structures are designed as efficient magnetic resonance imaging (MRI) contrast agents (CAs) with high relaxivity and stability.</p>

Gd(III) and Yb(III) Complexes Derived from a New Water-Soluble Dioxopolyazacyclohexane Macrocycle

“…Thermodynamic Stability. The thermodynamic stability of the MT14DCH lanthanide complexes was analyzed based on the procedure reported by Xu et al, 14 with slight modifications. Solutions of the Gd(III) and Yb(III) MT14DCH complexes were mixed with standardized DTPA solutions.…”

[rac-1,8-Bis(2-carbamoylethyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane]copper(II) diacetate tetrahydrate: crystal structure and Hirshfeld surface analysis

“…Owing to the multifarious applications of different metal complexes of a wide variety of macrocyclic ligands (Ali et al, 2019;Bernhardt & Sharpe, 2000;Lamani et al, 2018;Vicente et al, 2003;Xu et al, 2020), studies on some N-pendent macrocyclic ligands and their metal complexes were described by us recently Dey, Rabi, Palit et al, 2021). In a continuation of this work, a new N-pendent carbamoyl-derived macrocyclic ligand, 'tet-am', C 22 H 46 N 6 O 2 , prepared from 'tet-a 0 (an isomeric ligand of the hexamethyl tetrazamacrocyclic ligand) and acrylamide has been synthesized, by employing the procedure described for the preparation of a related N-pendent ligand .…”

Single-Atom Gadolinium Nano-Contrast Agents with High Stability for Tumor T1 Magnetic Resonance Imaging

“…Magnetic resonance imaging (MRI) is a powerful noninvasive diagnostic method for disease evaluations among diverse biomedical imaging modes, especially for early detection and accurate localization of tumors. − To overcome the low sensitivity of MRI, doctors have utilized contrast agents such as Gd-chelates to enhance the clinical imaging contrast by increasing the spin relaxation rates of water molecules in the body. − Nevertheless, because of the nonspecific distribution and rapid clearance of the small molecular Gd-chelates, they encounter the challenges of inadequate sensitivity and lack of selectivity for cancer diagnosis. , With the rapid development of nanotechnology, Gd-based nanomaterials are emerging as a promising substitute for Gd-chelates in cancer diagnosis because of better tumoral accumulation. − Gd-based nanomaterials also show improved relaxivity compared with Gd-chelates by increasing the rotational correlation time (τ r ) of the geometrically confined Gd elements. − However, most Gd atoms are inside the nanoparticles, and they are inaccessible to water molecules, resulting in the waste of Gd atoms. , Another significant problem that both the Gd-chelates and Gd-based nanomaterials face is the risk of nephrotoxicity caused by the release of toxic Gd 3+ ions . It is of great urgency to develop a kind of biocompatible, tumor-targeting, and stable Gd-based nano-contrast agents with high relaxivity for T 1 -weighted tumor MRI.…”