8 research outputs found
Biothiol Xenon MRI Sensor Based on Thiol-Addition Reaction
Biothiols such as cysteine (Cys),
homocysteine (Hcy), and glutathione
(GSH) play an important role in regulating the vital functions of
living organisms. Knowledge of their biodistribution in real-time
could help diagnose a variety of conditions. However, existing methods
of biothiol detection are invasive and require assays. Herein we report
a molecular biosensor for biothiol detection using the nuclear spin
resonance of <sup>129</sup>Xe. The <sup>129</sup>Xe biosensor consists
of a cryptophane cage encapsulating a xenon atom and an acrylate group.
The latter serves as a reactive site to covalently bond biothiols
through a thiol-addition reaction. The biosensor enables discrimination
of Cys from Hcy and GSH through the chemical shift and average reaction
rate. This biosensor can be detected at a concentration of 10 μM
in a single scan and it has been applied to detect biothiols in bovine
serum solution. Our results indicate that this biosensor is a promising
tool for the real-time imaging of biothiol distributions
Mitochondria Targeted and Intracellular Biothiol Triggered Hyperpolarized <sup>129</sup>Xe Magnetofluorescent Biosensor
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 <sup>129</sup>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 the <sup>129</sup>Xe chemical shift. Using Hyper-CEST (chemical exchange saturation
transfer) NMR, our biosensor shows a low detection limit at picomolar
(10<sup>–10</sup> 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