%0 Journal Article %J Chembiochem %D 2006 %T Optimization of xenon biosensors for detection of protein interactions %A Lowery, T. J. %A Garcia, S. %A Chavez, L. %A Ruiz, E. J. %A Wu, T. %A Brotin, T. %A Dutasta, J. P. %A King, D. S. %A Schultz, P. G. %A Pines, A. %A Wemmer, D. E. %K complexes %X

Hyperpolarized Xe-129 NMR spectroscopy can detect the presence of specific low-concentration biomolecular analytes by means of a xenon biosensor that consists of a water-soluble, targeted cryptophane-A cage that encapsulates the xenon. In this work, we use the prototypical biotinylated xenon biosensor to determine the relationship between the molecular composition of the xenon biosensor and the characteristics of protein-bound resonances. The effects of diastereomer overlap, dipole-dipole coupling, chemical-shift anisotropy, xenon exchange, and biosensor conformotional exchange on the protein-bound biosensor signal were assessed. It was found that an optimal protein-bound biosensor signal can be obtained by minimizing the number of biosensor diastereomers and using a flexible linker of appropriate length. Both the line width and sensitivity of chemical shift to protein binding of the xenon biosensor were found to be inversely proportional to linker length.

%B Chembiochem %V 7 %P 65-73 %8 Jan %@ 1439-4227 %G English %U ://WOS:000234701000012 %N 1 %M WOS:000234701000012 %! Optimization of xenon biosensors for detection of protein interactions %R Doi 10.1002/Cbic.200500327 %0 Journal Article %J Journal of the American Chemical Society %D 2004 %T Development of a functionalized xenon biosensor %A Spence, M. M. %A Ruiz, E. J. %A Rubin, S. M. %A Lowery, T. J. %A Winssinger, N. %A Schultz, P. G. %A Wemmer, D. E. %A Pines, A. %K drug discovery %X

NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of "remote" amplified detection. Here, we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of "functionalized" xenon to avidin leads to a change in the chemical shift of the encapsulated xenon in addition to a broadening of the resonance, both of which serve as NMR markers of ligand-target interaction. A control experiment in which the biotin-binding site of avidin was blocked with native biotin showed no such spectral changes, confirming that only specific binding, rather than nonspecific contact, between avidin and functionalized xenon leads to the effects on the xenon NMR spectrum. The exchange rate of xenon (between solution and cage) and the xenon spin-lattice relaxation rate were not changed significantly upon binding. We describe two methods for enhancing the signal from functionalized xenon by exploiting the laser-polarized xenon magnetization reservoir. We also show that the xenon chemical shifts are distinct for xenon encapsulated in different diastereomeric cage molecules. This demonstrates the potential for tuning the encapsulated xenon chemical shift, which is a key requirement for being able to multiplex the biosensor.

%B Journal of the American Chemical Society %V 126 %P 15287-15294 %8 Nov 24 %@ 0002-7863 %G English %U ://WOS:000225233600051 %N 46 %M WOS:000225233600051 %! Development of a functionalized xenon biosensor %R Doi 10.1021/Ja0483037 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2001 %T Functionalized xenon as a biosensor %A Spence, M. M. %A Rubin, S. M. %A Dimitrov, I. E. %A Ruiz, E. J. %A Wemmer, D. E. %A Pines, A. %A Yao, S. Q. %A Tian, F. %A Schultz, P. G. %K mri %X

The detection of biological molecules and their interactions is a significant component of modern biomedical research. In current biosensor technologies, simultaneous detection is limited to a small number of analytes by the spectral overlap of their signals. We have developed an NMR-based xenon biosensor that capitalizes on the enhanced signal-to-noise, spectral simplicity, and chemical-shift sensitivity of laser-polarized xenon to detect specific biomolecules at the level of tens of nanomoles. We present results using xenon "functionalized" by a biotin-modified supramolecular cage to detect biotin-avidin binding. This biosensor methodology can be extended to a multiplexing assay for multiple analytes.

%B Proceedings of the National Academy of Sciences of the United States of America %V 98 %P 10654-10657 %8 Sep 11 %@ 0027-8424 %G English %U ://WOS:000170966800030 %N 19 %M WOS:000170966800030 %! Functionalized xenon as a biosensor %R Doi 10.1073/Pnas.191368398