Xe hyperCEST NMR is a promising tool for imaging and disease detection applications. The hyperpolarizability of xenon atoms allows for increased sensitivities several orders of magnitude above 1H-NMR techniques. When coupled with chemical exchange saturation transfer (CEST), Xe hyperCEST NMR can exploit xenon host-guest chemistry to reduce the observed signal of the xenon dissolved in water, allowing for highly sensitive detection. While Xe hyperCEST NMR could provide sensitive molecular detection for applications in disease imaging, the lack of responsive turn-on probes for disease targets has limited the applications for Xe hyperCEST. We are therefore focused on developing a new class of turn-on probes for Xe hyperCEST that can be used for a wide variety of disease detection applications. We utlize the recently reported xenon host, cucurbit[6]uril (CB6), as it is commercially available, soluble in most buffers, and has favorable exchange parameters for hyperCEST. CB6 can be supramolecularly functionalized using CB6-catalyzed click chemistry to synthesize a variety of CB6 rotaxanes for applications in molecular detection with Xe hyperCEST NMR. By mechanically locking CB6 into a rotaxane, it is possible to suppress the hyperCEST response of the CB6.  Upon cleavage of the rotaxane by a chemical or biological event, the CB6 can be released to interact with Xe and produce a hyperCEST response. This method allows for the selective hyperCEST detection of CB6 in an environment of interest and can be tuned by modulating the axle components or the bulky rotaxane stoppers for a variety of applications.

Rotaxane probes for applications in molecular detection with Xe hyperCEST NMR

253rd National Meeting (2017)

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