An ESIPT solvatochromic fluorescent and colorimetric probe for sensitive and selective detection of copper ions in environmental samples and cell lines

Copper is one of the most important transition metals in our body for various physiological functions. An imbalance in the homeostasis of copper in our body can lead to various neurological disorders such as Alzheimer's disease, Parkinson's, and Menkes disease. As a result, there is a need for the detection of excess copper present in the environment and the human system. In this work, we have designed a quinoline-based fluorescent/colorimetric probe (QHS) for rapid and selective detection of copper ions via quenching of fluorescence/color change from yellow to peach which is visible to the naked eye. The probe displayed high selectivity towards copper(ii), i.e., Cu(ii) in the presence of different metal analytes in water samples. The sensing mechanism of the probe was confirmed by NMR, HRMS, IR spectroscopy, and SEM. The detection limit of Cu(ii) ions was found to be 0.493 & mu;M which is lower than the tolerable limit of copper (20 & mu;M) in drinking water as per the EPA. The probe was also utilized for the visualization of Cu(ii) in cell lines. The probe was also demonstrated for its application in real-time detection of aqueous samples using portable paper strips.