Mitochondria Targeted and Intracellular Biothiol Triggered Hyperpolarized ¹²⁹Xe Magnetofluorescent Biosensor

Abstract

Biothiols such as gluthathione (GSH), cysteine (Cys), homocysteine (Hcy), and thioredoxin (Trx) play vital roles in cellular metabolism. Various diseases are associated with abnormal cellular biothiol levels. Thus, the intracellular detection of biothiol levels could be a useful diagnostic tool. A number of methods have been developed to detect intracellular thiols, but sensitivity and specificity problems have limited their applications. To address these limitations, we have designed a new biosensor based on hyperpolarized xenon magnetic resonance detection, which can be used to detect biothiol levels noninvasively. The biosensor is a multimodal probe that incorporates a cryptophane-A cage as Xe NMR reporter, a naphthalimide moiety as fluorescence reporter, a disulfide bond as thiol-specific cleavable group, and a triphenylphosphonium moiety as mitochondria targeting unit. When the biosensor interacts with biothiols, disulfide bond cleavage leads to enhancements in the fluorescence intensity and changes in theXe chemical shift. Using Hyper-CEST (chemical exchange saturation transfer) NMR, our biosensor shows a low detection limit at picomolar (10 M) concentration, which makes a promise to detect thiols in cells. The biosensor can detect biothiol effectively in live cells and shows good targeting ability to the mitochondria. This new approach not only offers a practical technique to detect thiols in live cells, but may also present an excellent in vivo test platform for xenon biosensors.

Molecular Sensing with Host Systems for Hyperpolarized 129Xe

“…Importantly, this study showed that the choice of the dye also impacts cellular uptake where TAMRA was enabling better uptake than the previously used fluorescein (presumably due to more pronounced hydrophobicity of TAMRA which enables uptake into the membrane). A dye label can also be used to design a so-called “magnetofluorescent” biosensor: such a sensor yields a change in fluorescence upon target interaction that is also linked to a change in the HyperCEST signal [ 235 ].…”

Probing Reversible Guest Binding with Hyperpolarized 129Xe-NMR: Characteristics and Applications for Cucurbit[n]urils

“…Indeed, dimer formation was supported through MALDI and MD simulation-based results. However, the strong avidin binding to biotin is sufficient enough to hamper the btCB [7] dimerization [212] anticipated for such monofunctionalized CB[n].…”

High Resolution3He Pulmonary MRI

“…Exploiting these signals for diagnostic imaging purposes can be difficult since for example, only about 2% of inhaled xenon dissolves into the tissue barrier and RBC [76,79], and the corresponding T 2 * values are often short ($2 ms) [80]. There is an urgent need for efficient short-TE methods to acquire these short T 2 * signals and enable deeper study of a number of lung abnormalities such as ventilation/perfusion mismatch [81,82] and of other organs including xenon brain perfusion imaging [72,83] and imaging of the xenon-encapsulated Cryptophane-A functionalized with anti-cancer drugs [84].…”