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An Expanded Palette of Xenon-129 NMR Biosensors.
Acc Chem Res. 2016 10 18; 49(10):2179-2187.AC

Abstract

Molecular imaging holds considerable promise for elucidating biological processes in normal physiology as well as disease states, by determining the location and relative concentration of specific molecules of interest. Proton-based magnetic resonance imaging (1H MRI) is nonionizing and provides good spatial resolution for clinical imaging but lacks sensitivity for imaging low-abundance (i.e., submicromolar) molecular markers of disease or environments with low proton densities. To address these limitations, hyperpolarized (hp) 129Xe NMR spectroscopy and MRI have emerged as attractive complementary methodologies. Hyperpolarized xenon is nontoxic and can be readily delivered to patients via inhalation or injection, and improved xenon hyperpolarization technology makes it feasible to image the lungs and brain for clinical applications. In order to target hp 129Xe to biomolecular targets of interest, the concept of "xenon biosensing" was first proposed by a Berkeley team in 2001. The development of xenon biosensors has since focused on modifying organic host molecules (e.g., cryptophanes) via diverse conjugation chemistries and has brought about numerous sensing applications including the detection of peptides, proteins, oligonucleotides, metal ions, chemical modifications, and enzyme activity. Moreover, the large (∼300 ppm) chemical shift window for hp 129Xe bound to host molecules in water makes possible the simultaneous identification of multiple species in solution, that is, multiplexing. Beyond hyperpolarization, a 106-fold signal enhancement can be achieved through a technique known as hyperpolarized 129Xe chemical exchange saturation transfer (hyper-CEST), which shows great potential to meet the sensitivity requirement in many applications. This Account highlights an expanded palette of hyper-CEST biosensors, which now includes cryptophane and cucurbit[6]uril (CB[6]) small-molecule hosts, as well as genetically encoded gas vesicles and single proteins. In 2015, we reported picomolar detection of commercially available CB[6] via hyper-CEST. Inspired by the versatile host-guest chemistry of CB[6], our lab and others developed "turn-on" strategies for CB[6]-hyper-CEST biosensing, demonstrating detection of protein analytes in complex media and specific chemical events. CB[6] is starting to be employed for in vivo imaging applications. We also recently determined that TEM-1 β-lactamase can function as a single-protein reporter for hyper-CEST and observed useful saturation contrast for β-lactamase expressed in bacterial and mammalian cells. These newly developed small-molecule and genetically encoded xenon biosensors offer significant potential to extend the scope of hp 129Xe toward molecular MRI.

Authors+Show Affiliations

Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States.Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

27643815

Citation

Wang, Yanfei, and Ivan J. Dmochowski. "An Expanded Palette of Xenon-129 NMR Biosensors." Accounts of Chemical Research, vol. 49, no. 10, 2016, pp. 2179-2187.
Wang Y, Dmochowski IJ. An Expanded Palette of Xenon-129 NMR Biosensors. Acc Chem Res. 2016;49(10):2179-2187.
Wang, Y., & Dmochowski, I. J. (2016). An Expanded Palette of Xenon-129 NMR Biosensors. Accounts of Chemical Research, 49(10), 2179-2187.
Wang Y, Dmochowski IJ. An Expanded Palette of Xenon-129 NMR Biosensors. Acc Chem Res. 2016 10 18;49(10):2179-2187. PubMed PMID: 27643815.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - An Expanded Palette of Xenon-129 NMR Biosensors. AU - Wang,Yanfei, AU - Dmochowski,Ivan J, Y1 - 2016/09/19/ PY - 2016/10/19/pubmed PY - 2018/7/26/medline PY - 2016/9/20/entrez SP - 2179 EP - 2187 JF - Accounts of chemical research JO - Acc. Chem. Res. VL - 49 IS - 10 N2 - Molecular imaging holds considerable promise for elucidating biological processes in normal physiology as well as disease states, by determining the location and relative concentration of specific molecules of interest. Proton-based magnetic resonance imaging (1H MRI) is nonionizing and provides good spatial resolution for clinical imaging but lacks sensitivity for imaging low-abundance (i.e., submicromolar) molecular markers of disease or environments with low proton densities. To address these limitations, hyperpolarized (hp) 129Xe NMR spectroscopy and MRI have emerged as attractive complementary methodologies. Hyperpolarized xenon is nontoxic and can be readily delivered to patients via inhalation or injection, and improved xenon hyperpolarization technology makes it feasible to image the lungs and brain for clinical applications. In order to target hp 129Xe to biomolecular targets of interest, the concept of "xenon biosensing" was first proposed by a Berkeley team in 2001. The development of xenon biosensors has since focused on modifying organic host molecules (e.g., cryptophanes) via diverse conjugation chemistries and has brought about numerous sensing applications including the detection of peptides, proteins, oligonucleotides, metal ions, chemical modifications, and enzyme activity. Moreover, the large (∼300 ppm) chemical shift window for hp 129Xe bound to host molecules in water makes possible the simultaneous identification of multiple species in solution, that is, multiplexing. Beyond hyperpolarization, a 106-fold signal enhancement can be achieved through a technique known as hyperpolarized 129Xe chemical exchange saturation transfer (hyper-CEST), which shows great potential to meet the sensitivity requirement in many applications. This Account highlights an expanded palette of hyper-CEST biosensors, which now includes cryptophane and cucurbit[6]uril (CB[6]) small-molecule hosts, as well as genetically encoded gas vesicles and single proteins. In 2015, we reported picomolar detection of commercially available CB[6] via hyper-CEST. Inspired by the versatile host-guest chemistry of CB[6], our lab and others developed "turn-on" strategies for CB[6]-hyper-CEST biosensing, demonstrating detection of protein analytes in complex media and specific chemical events. CB[6] is starting to be employed for in vivo imaging applications. We also recently determined that TEM-1 β-lactamase can function as a single-protein reporter for hyper-CEST and observed useful saturation contrast for β-lactamase expressed in bacterial and mammalian cells. These newly developed small-molecule and genetically encoded xenon biosensors offer significant potential to extend the scope of hp 129Xe toward molecular MRI. SN - 1520-4898 UR - https://www.unboundmedicine.com/medline/citation/27643815/An_Expanded_Palette_of_Xenon_129_NMR_Biosensors_ L2 - https://dx.doi.org/10.1021/acs.accounts.6b00309 DB - PRIME DP - Unbound Medicine ER -