Dysprosium complexes can serve as transverse relaxation (T2) agents for water protons through chemical exchange and the Curie spin relaxation mechanism. Using a pair of matched dysprosium(III) complexes, Dy-L1 (contains one inner-sphere water) and Dy-L2 (no inner-sphere water), it is shown that the transverse relaxation of bulk water is predominantly an innersphere effect. The kinetics of water exchange at Dy-L1 were determined by 17O NMR. Proton transverse relaxation by Dy-L1 at high fields is governed primarily through a large chemical shift difference between free and bound water. Dy-L1 forms a noncovalent adduct with human serum albumin which dramatically lengthens the rotational correlation time, τR, causing the dipole-dipole component of the Curie spin mechanism to become significant and transverse relaxivity to increase by 3-8 times that of the unbound chelate. These findings aid in the design of new molecular species as efficient r2 agents.
- Curie spin
- Human serum
- T contrast agent
- Water exchange
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Radiological and Ultrasound Technology