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A phospholipid spin label used as a liposome‐associated MRI contrast agent
Author(s) -
Grant Chris W. M.,
Barber Kathryn R.,
Florio Eugene,
Karlik Stephen
Publication year - 1987
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910050409
Subject(s) - liposome , contrast (vision) , nuclear magnetic resonance , phospholipid , spin label , magnetic resonance imaging , chemistry , medicine , materials science , nanotechnology , computer science , physics , radiology , artificial intelligence , membrane , electron paramagnetic resonance , biochemistry
Given current clinical use of phospholipid bilayer structures (liposomes/vesicles) as non‐toxic drug delivery vehicles, we have addressed the possibility of employing the phospholipids themselves as MRI contrast agents. To this end we have synthesized phosphatidylcholine with a nitroxide spin label replacing one methyl residue of the choline headgroup. This material was mixed with natural phosphatidylcholine in mole ratios from 150 to 1:1 and used to prepare sonicated unilamellar vesicles in saline. Expected structural features of these vesicles were verified by freeze‐fracture electron microscopy. Proton T 1 values of saline were readily decreased to less than 0.3 s by such preparations, yielding a net relaxivity of 0.6 M −1 s −1 . The approach seems to be a realistic way of firmly associating a contrast agent of minimal toxicity with ordinary liposomes/vesicles in a manner that is not subject to leakage. © 1987 Academic Press, Inc.