Abstract
Dual-function chemosensors that combine the capability of colorimetric and fluorimetric detection of Cu2+ are still relatively rare. Herein, we report that a 3-hydroxyflavone derivative (E)-2-(4-(dimethylamino)styryl)-3-hydroxy-4H-chromen-4-one (4), which is a red-emitting fluorophore, could serve as a reversible colorimetric and fluorescence “turn-off” chemosensor for the detection of Cu2+. Upon addition of Cu2+ to 4 in neutral aqueous solution, a dramatic color change from yellow to purple-red was clearly observed, and its fluorescence was markedly quenched, which was attributed to the complexation between the chemosensor and Cu2+. Conditions of the sensing process had been optimized, and the sensing studies were performed in a solution of ethanol/phosphate buffer saline (v/v = 3:7, pH = 7.0). The sensing system exhibited high selectivity towards Cu2+. The limit of naked eye detection of Cu2+ was determined at 8 × 10−6 mol/L, whereas the fluorescence titration experiment showed a detection limit at 5.7 × 10−7 mol/L. The complexation between 4 and Cu2+ was reversible, and the binding constant was found to be 3.2 × 104 M−1. Moreover, bioimaging experiments showed that 4 could penetrate the cell membrane and respond to the intracellular changes of Cu2+ within living cells, which indicated its potential for biological applications.
Highlights
Copper is an essential transition element in the human body that plays a critical role in many biological processes
Copper is normally found as Cu(II) in water, and the permissible maximum level in drinking water is set at 3 × 10−5 mol/L by the World Health Organization (WHO) [5]
We report that a 3-hydroxyflavone derivative (E)-2-(4-(dimethylamino)styryl)-3-hydroxy-4H-chromen-4-one (4), which is a red-emitting fluorophore, could serve as a reversible colorimetric and fluorescence “turn-off” chemosensor for detection of Cu2+
Summary
Copper is an essential transition element in the human body that plays a critical role in many biological processes. High concentrations of copper can be found in the liver and brain [1]. Excessive uptake of copper would cause liver or kidney damage and is associated with various neurodegenerative diseases, such as Alzheimer’s disease and Wilson’s disease [3,4]. Copper is normally found as Cu(II) in water, and the permissible maximum level in drinking water is set at 3 × 10−5 mol/L by the World Health Organization (WHO) [5]. Due to the increasing discharge of metal waste from industry and agriculture, copper has been identified as an environmental pollutant [6], so it is highly important to develop sensitive and selective methods for the detection of Cu2+ in environmental and biological samples
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