A Highly Selective Colorimetric Sensor for Cysteine Detection

Abstract

Introducing a hybrid xanthene as a fluorophore, an 'ensemble'-based fluorescent sensor (E)-2-(6-(diethylamino)-2-((2-hydroxyphenylimino)methyl)-3-oxo-3H-xanthen-9-yl)benzoic acid (a) was designed and synthesised for detection of cysteine. Cysteine can release Cu II ion from the non-fluorescent a-Cu II complex. Then hydrolytic cleavage of Schiff base a produces a pink fluorescent compound 2-(6-(diethylamino)-2-formyl-3-oxo-3H-xanthen-9-yl)benzoic acid (2). We call this process a fluorescence off-on change. An obvious color change from purple a to pink 2 can be easily observed by the naked-eye. The calibration curve showed that the fluorescence intensity at 560 nm linearly increased over the cysteine concentration range of 0.379-100 μmol L-1 with a limit of detection of 0.379 μmol L-1. Sensor a-Cu II displayed excellent selectivity for cysteine, even homocysteine and glutathione did not show influence. The sensor was also used for detecting cysteine in human breast adenocarcinoma cells, which illustrates the practical value. Overall, the sensor appears to be useful for rapid, convenient and selective cysteine detection in living tissues.

Synthesis and Characterization of Eugenia uniflora L. Silver Nanoparticles and L‐Cysteine Sensor Application

“…Hyperhomocysteinemia is associated with atherosclerosis, congestive heart failure, age‐related macular degeneration, Alzheimer's disease, and cancer [2] . Cysteine deficiency may lead to edema, liver damage, skin lesions, and weakness [3] . Consequently, precise assessment of Cys levels in human bodies may aid the early diagnosis of some diseases.…”

“…[2] Cysteine deficiency may lead to edema, liver damage, skin lesions, and weakness. [3] Consequently, precise assessment of Cys levels in human bodies may aid the early diagnosis of some diseases.…”