A highly selective and sensitive ON–OFF–ON fluorescence chemosensor for cysteine detection in endoplasmic reticulum

• DOI: 10.1016/j.bios.2015.06.077
• Publication Date: 2015-07-06T20:33:41Z
• Authors: Qingtao Meng; Hongmin Jia; Peter Succar; Liang Zhao; Run Zhang; Chunying Duan; Zhiqiang Zhang
• Keywords: Biological Thiols; Living Cells; 2204 Biomedical Engineering; Molecular Probe Techniques; 1603 Electrochemistry; Biosensing Techniques; Endoplasmic Reticulum; Sensitivity and Specificity; 01 natural sciences; Cell Line; Coumarins; Humans; Cysteine; Homocysteine; Iridium(Iii) Complex; Aqueous-Solution; Protein; 500; Reproducibility of Results; Equipment Design; Probe; Glutathione; 0104 chemical sciences; 3. Good health; Equipment Failure Analysis; Spectrometry, Fluorescence; Molecular Probes; Ruthenium(Ii) Complex; 1305 Biotechnology; Copper; Rational Design; 1304 Biophysics

A new complex between coumarin-based ligand (CL) and copper ion has been prepared and applied to be an ON-OFF-ON reversible fluorescence chemosensor for the detection of Cys with high sensitivity and specificity. In HEPES buffer, CL displayed high affinity towards Cu(2+) ion over other physiological and environmental metal ions, accompanied with a 98.4% of fluorescence quenching. In the presence of Cys, the detachment of Cu(2+) ion of CL-Cu(2+) ensemble led to the liberation of the fluorophore, CL, and thus fluorescence was recovered. The results of absorption and emission spectroscopy analyses confirmed that the fluorescence turn ON response of CL-Cu(2+) ensemble was selective towards Cys only with high sensitivity (detection of limit, 7.2×10(-7) M). Confocal microscopy studies indicated that the lipophilic CL targets the endoplasmic reticulum (ER) of live cells, where it could be functioned as a fluorescent chemosensor for visualization of Cys in this organelle. Quantitative fluorescence detection of Cys in ER was successfully realized by flow cytometry analysis. The developed chemosensor was further applied to detect Cys in real urine samples with great recoveries ranges from 95.41% to 107.40%.