@article {257, title = {Band-selective chemical exchange saturation transfer imaging with hyperpolarized xenon-based molecular sensors}, journal = {Journal of Magnetic Resonance}, volume = {213}, year = {2011}, note = {J Magn Reson847UKTimes Cited:3Cited References Count:29}, month = {Dec}, pages = {14-21}, abstract = {

Molecular imaging based on saturation transfer in exchanging systems is a tool for amplified and chemically specific magnetic resonance imaging. Xenon-based molecular sensors are a promising category of molecular imaging agents in which chemical exchange of dissolved xenon between its bulk and agent-bound phases has been use to achieve sub-picomolar detection sensitivity. Control over the saturation transfer dynamics, particularly when multiple exchanging resonances are present in the spectra, requires saturation fields of limited bandwidth and is generally accomplished by continuous wave irradiation. We demonstrate instead how band-selective saturation sequences based on multiple pulse inversion elements can yield saturation bandwidth tuneable over a wide range, while depositing less RF power in the sample. We show how these sequences can be used in imaging experiments that require spatial-spectral and multispectral saturation. The results should be applicable to all CEST experiments and, in particular, will provide the spectroscopic control required for applications of arrays of xenon chemical sensors in microfluidic chemical analysis devices. (C) 2011 Elsevier Inc. All rights reserved.

}, keywords = {xe-129}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2011.06.027}, url = {://WOS:000296997800002}, author = {Meldrum, T. and Bajaj, V. S. and Wemmer, D. E. and Pines, A.} } @article {263, title = {A Xenon-Based Molecular Sensor Assembled on an MS2 Viral Capsid Scaffold}, journal = {Journal of the American Chemical Society}, volume = {132}, year = {2010}, note = {J Am Chem Soc589OATimes Cited:20Cited References Count:23}, month = {May 5}, pages = {5936-+}, abstract = {

In MRI, anatomical structures are most often differentiated by variations in their bulk magnetic properties. Alternatively, exogenous contrast agents can be attached to chemical moieties that confer affinity to molecular targets; the distribution of such contrast agents can be imaged by magnetic resonance. Xenon-based molecular sensors are molecular imaging agents that rely on the reversible exchange of hyperpolarized xenon between the bulk and a specifically targeted host-guest complex. We have incorporated similar to 125 xenon sensor molecules in the interior of an MS2 viral capsid, conferring multivalency and other properties of the viral capsid to the sensor molecule. The resulting signal amplification facilitates the detection of sensor at 0.7 pM, the lowest to date for any molecular imaging agent used in magnetic resonance. This amplification promises the detection of chemical targets at much lower concentrations than would be possible without the capsid scaffold.

}, keywords = {nmr}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja100319f}, url = {://WOS:000277158500007}, author = {Meldrum, T. and Seim, K. L. and Bajaj, V. S. and Palaniappan, K. K. and Wu, W. and Francis, M. B. and Wemmer, D. E. and Pines, A.} } @article {264, title = {Xenon-based molecular sensors in lipid suspensions}, journal = {Journal of Magnetic Resonance}, volume = {205}, year = {2010}, note = {J Magn Reson627SZTimes Cited:8Cited References Count:23}, month = {Aug}, pages = {242-246}, abstract = {

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.

}, keywords = {binding}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2010.05.005}, url = {://WOS:000280064500008}, author = {Meldrum, T. and Schroder, L. and Denger, P. and Wemmer, D. E. and Pines, A.} } @article {276, title = {Temperature response of (129)Xe depolarization transfer and its application for ultrasensitive NMR detection}, journal = {Physical Review Letters}, volume = {100}, year = {2008}, note = {Phys Rev Lett320JWTimes Cited:12Cited References Count:8}, month = {Jun 27}, abstract = {

Trapping xenon in functionalized cryptophane cages makes the sensitivity of hyperpolarized (HP) (129)Xe available for specific NMR detection of biomolecules. Here, we study the signal transfer onto a reservoir of unbound HP xenon by gating the residence time of the nuclei in the cage through the temperature-dependant exchange rate. Temperature changes larger than similar to 0.6 K are detectable as an altered reservoir signal. The temperature response is adjustable with lower concentrations of caged xenon providing more sensitivity at higher temperatures. Ultrasensitive detection of functionalized cryptophane at 310 K is demonstrated with a concentration of 10 nM, corresponding to a similar to 4000-fold sensitivity enhancement compared to conventional detection. This makes HPNMR capable of detecting such constructs in concentrations far below the detection limit of benchtop uv-visible light absorbance.

}, keywords = {biosensors}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.100.257603}, url = {://WOS:000257230500066}, author = {Schroeder, L. and Meldrum, T. and Smith, M. and Lowery, T. J. and Wemmer, D. E. and Pines, A.} } @article {277, title = {Temperature-controlled molecular depolarization gates in nuclear magnetic resonance}, journal = {Angewandte Chemie-International Edition}, volume = {47}, year = {2008}, note = {Angew Chem Int Edit308BXTimes Cited:13Cited References Count:19}, pages = {4316-4320}, keywords = {mri}, isbn = {1433-7851}, doi = {Doi 10.1002/Anie.200800382}, url = {://WOS:000256364400007}, author = {Schroder, L. and Chavez, L. and Meldrum, T. and Smith, M. and Lowery, T. J. and Wemmer, D. E. and Pines, A.} }