Quantitative Assessment of Xenon Exchange Kinetics with Cucurbit[6]uril in Physiological Saline

다국어 초록 (Multilingual Abstract)

Cucurbit[6]uril and xenon form supramolecular complexes that are of great potential for biosensing by NMR. This host‐guest system acts alike a signaler in sensors facilitating the ultrasensitive detection of biomarkers by saturation transfer of chemically exchanging, hyperpolarized 129Xe. Here, the exchange process is evaluated by NMR exchange spectroscopy utilizing the preparation of anti‐parallel longitudinal magnetization with respect to free and host‐bound xenon and the variation of xenon concentration. Evidence for dissociative as well as degenerate exchange mechanisms is revealed by a linear regression analysis of the determined exchange rates resulting in rate coefficients of 1131±11 s−1 (2390±70 s−1) and 108500±4900 M−1 s−1 (174200±13900 M−1 s−1), respectively, and an affinity constant of 289±8 M−1 (278±14 M−1) in physiological saline at 298 K (310 K). The results elucidate the supramolecular exchange and underpin the high efficacy for biosensing of this host‐guest system. The approach is generally applicable to enhanced host‐xenon exchange dynamics, yet slow on the NMR timescale, for quantitative kinetics and biosensing analyses.
Disentangling supramolecular kinetics: dissociative and degenerate mechanisms are revealed for the cucurbit[6]uril‐xenon host‐guest system in physiological saline by NMR exchange spectroscopy. Rate coefficients are quantified for the exchange regime on the sub‐millisecond timescale. The data prove the high efficacy of this system for ultrasensitive biosensing applications. Overall, the method supports quantitative assessments of sensors.