Size-induced enhancement of chemical exchange saturation transfer (CEST) contrast in liposomes.

TitleSize-induced enhancement of chemical exchange saturation transfer (CEST) contrast in liposomes.
Publication TypeJournal Article
Year of Publication2008
AuthorsZhao JM, Har-el Y-el, McMahon MT, Zhou J, Sherry DA, Sgouros G, Bulte JWM, van Zijl PCM
JournalJournal of the American Chemical Society
Volume130
Issue15
Pagination5178-84
Date Published2008 Apr 16
Abstract

Liposome-based chemical exchange saturation transfer (lipoCEST) agents have shown great sensitivity and potential for molecular magnetic resonance imaging (MRI). Here we demonstrate that the size of liposomes can be exploited to enhance the lipoCEST contrast. A concise analytical model is developed to describe the contrast dependence on size for an ensemble of liposomes. The model attributes the increased lipoCEST contrast in smaller liposomes to their larger surface-to-volume ratio, causing an increased membrane water exchange rate. Experimentally measured rates correlate with size, in agreement with the model. The water permeability of liposomal membrane is found to be 1.11 +/- 0.14 microm/s for the specific lipid composition at 22 degrees C. Availability of the model allows rational design of the size of liposomes and quantification of their properties. These new theoretical and experimental tools are expected to benefit applications of liposomes to sensing the cellular environment, targeting and imaging biological processes, and optimizing drug delivery properties.

DOI10.1203/PDR.0b013e318174e70e
Alternate JournalJ. Am. Chem. Soc.