Abstract
Copper is an essential element in living systems and plays an important role in human physiology; therefore, methods to detect the concentration of copper ions in living organisms are important. Herein, we report a highly water-soluble naphthalimide-based fluorescent probe that can be used for the detection of Cu2+. The probe, BNQ, has high selectivity and sensitivity. The fluorescence intensity of the probe at 520 nm was visible to the naked eye under a UV lamp; upon the gradual addition of Cu2+, there was a colour change from green to nearly colourless. Furthermore, the detection limit of BNQ for Cu2+ was 45.5 nM. The detection mechanism was investigated using a Job's plot and density functional theory (DFT) calculations. In addition, owing to great biocompatibility, we were able to successfully use BNQ to detect Cu2+ in living HeLa cells with low toxicity.
Highlights
Even when present in trace amounts, copper, a mineral micronutrient, has been associated with a wide range of cellular processes; it plays a vital role as a coenzyme in free-radical scavenging and is involved with mitochondrial respiration, collagen and elastin synthesis, iron metabolism, erythropoiesis, and leukopoiesis.[1,2,3,4,5,6] The average concentration of copper in human blood is 100–150 mg dLÀ1 and the recommended intake of copper for humans is 0.9 mg each day.[7]
Copper de ciency leads to Menkes disease,[10,11] haematological neurological sequelae, and complications caused by malabsorption, including macrocytic anaemia, myelopathy, chronic diarrhoea, celiac disease, and in ammatory bowel disease (IBD).[6,12]
It has been reported that copper from drinking water and food can increase its concentration in human blood and accumulate in the kidney, cornea, and brain, which can lead to disease.[24]
Summary
A variety of elds, such as mining, smelting, and fertilising, and due to the abuse of molluscicides and fungicides, humans are exposed to copper via contaminants through air, drinking water, soil, and food.[19,20,21,22,23] It has been reported that copper from drinking water and food can increase its concentration in human blood and accumulate in the kidney, cornea, and brain, which can lead to disease.[24]. Include atomic absorption spectroscopy, electrochemical sensing, piezoelectric quartz crystal impedance studies, and inductively coupled plasma atomic emission spectrometry.[24,25,26] These methods require complicated preparation procedures, expensive instruments and trained professional technicians.[27] Recently, uorescent probes have gained attention due to several notable advantages, including high sensitivity, high speci city, good biocompatibility, simpli ed operation, and minimal invasiveness.[28,29,30,31] Many recent reports describe excellent uorescent sensors for detecting Cu2+.32–38. More research is required to develop uorescent probes with strong hydrophilia, good biocompatibility, low toxicity, high anti-interference ability, and easy preparation. Was based on excited state double-proton transfer (ESDPT), which is not commonly used for Cu2+ detection. This has been con rmed with Job's plot analysis and DFT studies. This study may provide a feasible plan for the speci c detection of Cu2+ in biomedicine and biological pathology
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