Abstract #0152

Imaging Ca2+ Using Fluorine Chemical Exchange Saturation Transfer (19F-CEST)

Amnon Bar-Shir¹,², Assaf A. Gilad¹,², Kannie W.Y. Chan¹,³, Guanshu Liu¹,³, Peter C.M. van Zijl¹,³, Michael T. McMahon¹,³, Jeff W.M. Bulte¹,²

¹Department of Radiology, Johns Hopkins University, Baltimore, MD, United States; ²Institute for Cell Engineering, Johns Hopkins University, Baltimore, MD, United States; ³F.M. Kirby Research Center, Kennedy Krieger Institute, Baltimore, MD, United States

Although Ca²⁺ ions are involved in a myriad of biological signaling processes, a non-invasive means of detecting micromolar Ca²⁺ levels remains a formidable challenge. We present an approach for specifically sensing the presence of Ca²⁺ ions through its substrate binding kinetics by exploiting the chemical shift change of ¹⁹F upon binding of Ca²⁺ to the fluorinated chelator 1,2-Bis-[2-bis(carboxymethyl)amino-5-¹⁹fluorophenoxy]ethane (5-¹⁹FBAPTA). Using RF labeling at the bound-¹⁹F frequency and detection of label transfer to the free-¹⁹F frequency (Δω=5.8ppm) in millimolar concentration substrate, we were able to amplify the signal of Ca²⁺ with supreme specificity over other divalent cations.