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A new magnetic resonance imaging (MRI) molecular sensor for hydrogen sulfide detection and imaging using the nuclear spin resonance of hyperpolarized 129Xe is developed. The designed MRI sensor employs cryptophane for NMR sensing, together with an azide group serving as a reaction site. It demonstrates a 'proof-of-concept' that a fluorescent H2S probe can be linked to a xenon-binding cryptophane and thereby converted into an MRI probe, which could provide a very generalizable template. [ABSTRACT FROM AUTHOR]

Mercury pollution, in the form of mercury ions (Hg2+), is a major health and environmental hazard. Commonly used sensors are invasive and limited to point measurements. Fluorescence-based sensors do not provide depth resolution needed to image spatial distributions. Herein we report a novel sensor capable of yielding spatial distributions by MRI using hyperpolarized 129Xe. A molecular clamp probe was developed consisting of dipyrrolylquinoxaline (DPQ) derivatives and twocryptophane-A cages. The DPQ derivatives act as cation receptors whereas cryptophane-A acts as a suitable host molecule for xenon. When the DPQ moiety interacts with mercury ions, the molecular clamp closes on the ion. Due to overlap of the electron clouds of the two cryptophane-A cages, the shielding effect on the encapsulated Xe becomes important. This leads to an upfield change of the chemical shift of the encapsulated Xe. This sensor exhibits good selectivity and sensitivity toward the mercury ion. This mercury-activated hyperpolarized 129Xe-based chemosensor is a new concept method for monitoring Hg2+ ion distributions by MRI. [ABSTRACT FROM AUTHOR]

Hyperpolarization is one of the methods for NMR signal enhancement. NMR sensitivity can be further enhanced by combining hyperpolarization with chemical exchange saturation transfer (CEST), which termed “Hyper‐CEST”. A H2S sensor is reported that contains a cryptophane group for NMR sensing and a naphthalimide group for fluorescence sensing, together with an azide group as the reaction site. Upon reacting with H2S, the fluorescence and 129Xe NMR signal changes, which may provide a universal template for converting a fluorescence sensor into an 129Xe Hyper‐CEST MRI sensor. More information can be found in the Communication by X. Zhou, M. Liu, et al. on page 7648. [ABSTRACT FROM AUTHOR]