Novel radical-responsive MRI contrast agent based on paramagnetic liposomes

✍ Scribed by Christian Gløgård; Gry Stensrud; Silvio Aime

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 113 KB
• Volume: 41
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1208

✦ Synopsis

Abstract

A novel, radical responsive MRI contrast agent based on a gadolinium chelate conjugated to a liposome through a disulfide linker was synthesized, with the aim of pursuing the in vivo mapping of radicals. The liposome was prepared by incorporating a thiol‐activated phospholipid, which was subsequently reacted with a gadolinium chelate containing a free thiol group. The long reorientational motion of the supramolecular adduct endows the paramagnetic agent with a relaxivity significantly higher than that of the free complex. The disulfide bond represents a radical‐sensitive moiety and a large decrease in contrast efficacy (T~1~ relaxivity) is shown upon its cleavage. A preliminary assessment of the system was made by means of in vitro gamma‐irradiation and thiol–disulfide bond exchange with dithiothreitol. Both methods showed a clear dose‐dependent decrease in T~1~‐relaxivity. Copyright © 2003 John Wiley & Sons, Ltd.