Cysteine‐Mediated Intracellular Building of Luciferin to Enhance Probe Retention and Fluorescence Turn‐On

Abstract

The development of sensitive and selective small molecular probes that enable real-time detection of endogenous cysteine (Cys) has become an attractive topic because of the essential roles played by Cys in controlling the cellular nitrogen balance and in maintaining biological redox homeostasis. Herein, we report a Cys-specific probe, 2-cyanobenzothiazol-6-yl acrylate (CBTOA), that shows not only fluorescence turn-on for sensitive detection of endogenous Cys but also enhanced probe retention inside cells for real-time monitoring of Cys levels upon external stimulation. Cys-mediated intracellular formation of luciferin from CBTOA was the key strategy leading to this new type of fluorogenic probe. CBTOA showed fast response to Cys in living cells and liver tissue slices with high sensitivity and selectivity. By using CBTOA as a real-time probe, we were able to monitor the change in Cys levels in living HeLa cells under ROS-induced oxidative stress as well as in human mesenchymal stem cells during adipogenic differentiation.

Photoelectrochemical Bioanalysis Platform of Gold Nanoparticles Equipped Perovskite Bi4NbO8Cl

“…Obviously, the Au NPs/Bi 4 NbO 8 Cl electrode possessed a higher sensitivity and fast responses with a wider linearity region against cysteine detection. Given the concentrations of cysteine in human serum varies from 165.1 to 335.3 μmol L –1 , − and these results indicated the potential suitability of the developed system for cysteine detection in biological samples. Incidentally, using the developed electrode, we also conducted the PEC detection of GSH, with the results and corresponding discussion as shown with Figures S7 and S8.…”

Firefly Luciferin‐Inspired Biocompatible Chemistry for Protein Labeling and In Vivo Imaging

“…In addition to bioluminescence, the change of fluorescenceg enerating from the fast reaction betweenC BT andi ntracellular l-Cysc ould also be readily appliedt ob uild fluorogenic probesf or cell imaging. [128][129][130] Another advantage of the reaction is the formation of condensation product with as ingle stereo/regioisomer, which allows for precise control of DNA modifications [131] or site-specific immobilization of biomolecules. [132] Other applications such as controlling of drug delivery for overcoming multidrug resistance have been demonstrated as well.…”

“…Caspase‐3 controlled building of firefly luciferin for bioluminescence imaging of tumor apoptosis in mice and d ‐Cys‐dependent production of firefly luciferin for bioluminescence detection of d ‐amino acid oxidase activity have been also reported based on this reaction. In addition to bioluminescence, the change of fluorescence generating from the fast reaction between CBT and intracellular l ‐Cys could also be readily applied to build fluorogenic probes for cell imaging . Another advantage of the reaction is the formation of condensation product with a single stereo/regioisomer, which allows for precise control of DNA modifications or site‐specific immobilization of biomolecules .…”

Molecular imaging of enzyme activity in vivo using activatable probes

“…These probes contain a fluorophore that is capped with an enzyme recognition substrate to quench their fluorescence, and after enzymatic removal of the capping substrate, the fluorescence is recovered. Extremely high turn on ratios are commonly observed for these probes [16,17]. Pre-quenched probes are another type of widely used activatable optical imaging probes, in which a fluorophore and a quencher are linked together via an enzyme-cleavable peptide substrate.…”