%0 Journal Article %J Chemphyschem %D 2010 %T MRI Thermometry Based on Encapsulated Hyperpolarized Xenon %A Schilling, F. %A Schroder, L. %A Palaniappan, K. K. %A Zapf, S. %A Wemmer, D. E. %A Pines, A. %K xe-129 %X

A new approach to MRI thermometry using encapsulated hyperpolarized xenon is demonstrated The method is based on the temperature dependent chemical shift of hyperpolarized xenon in a cryptophane-A cage This shift is linear with a slope of 029 ppm degrees C(-1) which is perceptibly higher than the shift of the proton resonance frequency of water (ca 0 01 ppm degrees C(-1)) that is currently used for MRI thermometry Using spectroscopic imaging techniques, we collected temperature maps of a phantom sample that could discriminate by direct NMR detection between temperature differences of 0 1 degrees C at a sensor concentration of 150 mu M Alternatively, the xenon-in-cage chemical shift was determined by indirect detection using saturation transfer techniques (Hyper-CEST) that allow detection of nanomolar agent concentrations Thermometry based on hyperpolarized xenon sensors improves the accuracy of currently available MRI thermometry methods, potentially giving rise to biomedical applications of biosensors functionalized for binding to specific target molecules

%B Chemphyschem %V 11 %P 3529-3533 %8 Nov 15 %@ 1439-4235 %G English %U ://WOS:000285080600023 %N 16 %M WOS:000285080600023 %! MRI Thermometry Based on Encapsulated Hyperpolarized Xenon %R Doi 10.1002/Cphc.201000507 %0 Journal Article %J Journal of Magnetic Resonance %D 2010 %T Xenon-based molecular sensors in lipid suspensions %A Meldrum, T. %A Schroder, L. %A Denger, P. %A Wemmer, D. E. %A Pines, A. %K binding %X

There have been many proposals to use xenon-based molecular sensors in biological settings. Fundamental to understanding the properties of these sensors in vivo is characterizing their behavior in lipid environments. We report the investigation of xenon-based molecular sensors in suspensions of lipid vesicles with a size comparable to cells. We detail spectroscopic properties of sensors associated with lipid vesicles as well as those in equilibrium in the surrounding solution. We characterize the dependence of the spectral parameters on temperature, relevant for studies at physiological temperatures. We also demonstrate the ability to perform selective saturation transfer (Hyper-CEST) between sensor, both lipid bound and unbound, and the bulk solution. Lastly, we demonstrate the applicability of saturation transfer in the heterogeneous medium as an imaging modality. (C) 2010 Elsevier Inc. All rights reserved.

%B Journal of Magnetic Resonance %V 205 %P 242-246 %8 Aug %@ 1090-7807 %G English %U ://WOS:000280064500008 %N 2 %M WOS:000280064500008 %! Xenon-based molecular sensors in lipid suspensions %R Doi 10.1016/J.Jmr.2010.05.005 %0 Journal Article %J Angewandte Chemie-International Edition %D 2008 %T Temperature-controlled molecular depolarization gates in nuclear magnetic resonance %A Schroder, L. %A Chavez, L. %A Meldrum, T. %A Smith, M. %A Lowery, T. J. %A Wemmer, D. E. %A Pines, A. %K mri %B Angewandte Chemie-International Edition %V 47 %P 4316-4320 %@ 1433-7851 %G English %U ://WOS:000256364400007 %N 23 %M WOS:000256364400007 %! Temperature-controlled molecular depolarization gates in nuclear magnetic resonance %R Doi 10.1002/Anie.200800382 %0 Journal Article %J Science %D 2006 %T Molecular imaging using a targeted magnetic resonance hyperpolarized biosensor %A Schroder, L. %A Lowery, T. J. %A Hilty, C. %A Wemmer, D. E. %A Pines, A. %K agents %X

A magnetic resonance approach is presented that enables high-sensitivity, high-contrast molecular imaging by exploiting xenon biosensors. These sensors link xenon atoms to specific biomolecular targets, coupling the high sensitivity of hyperpolarized nuclei with the specificity of biochemical interactions. We demonstrated spatial resolution of a specific target protein in vitro at micromolar concentration, with a readout scheme that reduces the required acquisition time by >3300-fold relative to direct detection. This technique uses the signal of free hyperpolarized xenon to dramatically amplify the sensor signal via chemical exchange saturation transfer (CEST). Because it is similar to 10,000 times more sensitive than previous CEST methods and other molecular magnetic resonance imaging techniques, it marks a critical step toward the application of xenon biosensors as selective contrast agents in biomedical applications.

%B Science %V 314 %P 446-449 %8 Oct 20 %@ 0036-8075 %G English %U ://WOS:000241382500036 %N 5798 %M WOS:000241382500036 %! Molecular imaging using a targeted magnetic resonance hyperpolarized biosensor %R Doi 10.1126/Science.1131847