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

Jason M. Zhao, Yah El Har-el, Michael T. McMahon, Jinyuan Zhou, A. Dean Sherry, George Sgouros, Jeff W.M. Bulte, Peter C.M. Van Zijl

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


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 NpoCEST 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 μm/s for the specific lipid composition at 22°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.

Original languageEnglish (US)
Pages (from-to)5178-5184
Number of pages7
JournalJournal of the American Chemical Society
Issue number15
StatePublished - Apr 16 2008

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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