Open AccessSpectral properties of a bifunctional PARACEST europium chelate: an intermediate for targeted imaging applications
Author(s) -
Adair Christopher,
Woods Mark,
Zhao Piyu,
Pasha Azhar,
Winter Patrick M.,
Lanza Gregory M.,
Athey Phillip,
Sherry A. Dean,
Kiefer Garry E.
Publication year - 2007
Publication title -
contrast media & molecular imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.714
H-Index - 50
eISSN - 1555-4317
pISSN - 1555-4309
DOI - 10.1002/cmmi.125
Subject(s) - bifunctional , europium , chemistry , lanthanide , ligand (biochemistry) , chelation , dota , gadolinium , combinatorial chemistry , inorganic chemistry , ion , organic chemistry , catalysis , biochemistry , receptor
This report describes a preliminary study to investigate the effect of structural variations in a bifunctional ligand being developed for targeted PARACEST applications. Utilizing Eu‐DOTA‐4AmCE as the functional PARACEST core, a nitro‐aromatic functionality was incorporated to provide the point for conjugation. This intermediate possesses a coordinated water proton signal at 57 ppm which upon saturation produces a 22% decrease in bulk water signal intensity using 10 m M agent. Curve fitting analysis of the CEST spectrum to an exchange model based upon modified Bloch equations gave an estimate of 687 ± 100 µs for the bound water lifetime ( τ m ). Although substantially longer than the 382 µs observed for the parent chelate structure, this water exchange rate remains in the necessary window to produce a significant CEST effect. These findings demonstrate the need to recognize the influence of bifunctional linkers on water exchange rates in lanthanide complexes of this type and the potential for using this functionality as a means of fine‐tuning PARACEST performance. Copyright © 2007 John Wiley & Sons, Ltd.