“Turn-on” fluorescence probe for selective recognition of endogenous and exogenous cysteine in cells

Novel Bis-Camphor-Derived Colorimetric and Fluorescent Probe for Rapid and Visual Detection of Cysteine and Its Versatile Applications in Food Analysis and Biological Imaging

A new colorimetric and fluorescent turn-on probe named 2,4-bis(camphor-3-methylene)phenylacrylate (BCP-Cys) was designed for highly sensitive and specific monitoring of cysteine (Cys). The probe BCP-Cys was strategically constructed by employing a new bis-camphor-derived scaffold (BCP-OH) as the fluorophore and an acrylate group as the recognition site and fluorescence quencher. The acrylate group of BCP-Cys could be exclusively cleaved by Cys and release the fluorophore BCP-OH, thereby causing a significantly enhanced red fluorescence and a naked-eye colorimetric change from colorless to yellow. The probe BCP-Cys exhibited promising sensing performances for Cys including large Stokes shift (184 nm), fast response time (<1 min), wide linear range (0-100 nM), and low detection limit (0.0728 μM). Moreover, the probe BCP-Cys could be utilized as a powerful tool for real-time determination of Cys levels within different food samples, such as onion, cabbage, broccoli, garlic, cauliflower, and bamboo sprout. In addition, this probe was also capable of imaging endogenous and exogenous Cys in living cells.

A novel near-infrared fluorescent probe based on isophorone for the bioassay of endogenous cysteine

A dicyanoisophorone/acrylate-combined probe (DDP) was synthesized and designed as a near-infrared (NIR) fluorescent sensor for the rapid identification of Cys over Hcy and GSH in aqueous solution with a large Stokes shift (143 nm). The detection limit of Cys was 1.23 μM, which was lower than that of the intracellular Cys concentration. DDP was cell membrane-permeable and had been successfully applied to the detection of intracellular Cys in HeLa cells. The detection mechanism was determined by ¹H NMR titration, MS and DFT calculations.

Nanoscale Metal-Organic Layers Detect Mitochondrial Dysregulation and Chemoresistance via Ratiometric Sensing of Glutathione and pH

Mitochondrial dysregulation controls cell death and survival by changing endogenous molecule concentrations and ion flows across the membrane. Here, we report the design of a triply emissive nanoscale metal-organic layer (nMOL), NA@Zr-BTB/F/R, for sensing mitochondrial dysregulation. Zr-BTB nMOL containing Zr₆ secondary building units (SBUs) and 2,4,6-tris(4-carboxyphenyl)aniline (BTB-NH₂) ligands was postsynthetically functionalized to afford NA@Zr-BTB/F/R by exchanging formate capping groups on the SBUs with glutathione(GSH)-selective (2E)-1-(2'-naphthyl)-3-(4-carboxyphenyl)-2-propen-1-one (NA) and covalent conjugation of pH-sensitive fluorescein (F) and GSH/pH-independent rhodamine-B (R) to the BTB-NH₂ ligands. Cell imaging demonstrated NA@Zr-BTB/F/R as a ratiometric sensor for mitochondrial dysregulation and chemotherapy resistance via GSH and pH sensing.