The Role of Water Exchange in Attaining Maximum Relaxivities for Dendrimeric MRI Contrast Agents

Abstract

Macrocyclic Gd"' complexes attached to dendrimers represent a new class of potential MRI contrast agents. They have an extended lifetime in the blood pool, which is indispensable for their application in magnetic resonance angiography, and high relaxivities, which reduce the dose required to produce quality images. We performed a variable-temperature and -pressure "0 NMR study in aqueous solution and at 14.

Multi-functional liposomes having temperature-triggered release and magnetic resonance imaging for tumor-specific chemotherapy

“…for Gd-DOTA-conjugated PAMAM dendrimers increased with the dendrimer generation, because of the increase of rotational correlation time of the whole molecule, which increases with the molecular weight, and limited internal rotational motions of Gd-DOTA moieties connected to the rather rigid backbone of the dendrimer [41]. Therefore, it is likely that the Gd-DOTA residues attached to larger G3 dendron with highly crowded chain terminals might decrease their mobility and increase their rotational correlation time, resulting in higher relaxivity of the G3-DL-DOTA-Gd than G1-DL-DOTA-Gd.…”

High Relaxivity Confined to a Small Molecular Space: A Metallostar‐Based, Potential MRI Contrast Agent

“…[7] [Fe{Gd(tpy-DTTA)} 2 ] and [Fe{Gd(phen)(HDO3A)} 3 ] 2+ [4] are self-assembled structures. Gadomer 17, [10] [G5{Gd(DO3A)} 52 ], [11] and [G10{Gd(DOTA)} 1850 ] [8] are dendrimers. The effective relaxivities were calculated at 20 MHz and 37 8C, except for the last three columns which were determined at 25 8C.…”

Enhanced imaging properties of a GdIII complex with unusually large relaxivity

“…However, it is known that Eq. (3) provides τ R values one order of magnitude larger than those obtained from 17 O or 13 C NMR data [15]. The reason is that NMR, as opposed to viscosity, is directly sensitive to the internal motions of the molecules themselves.…”