Photoswitchable hemithioindigo inspired copper ion selective sensing with excellent selectivity and versatile operational modes

• Published in: Sensors and actuators. B, Chemical Vol. 381; p. 133437
• Main Authors: Chen, Qinghan, Wang, Yifu, Zhai, Jingying, Xie, Xiaojiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2023
• Subjects: Cell imaging; Copper; Fluorescent probe; Hemithioindigo; Lysosomes; Photoswitch; Lysosomes; Cell imaging; Copper; Hemithioindigo; Fluorescent probe; Photoswitch
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2023.133437

Copper is an essential element in living organisms and the monitoring of copper ions in aquatic environments and biological systems is of great significance. Inspired by a family of visible light responsive photoswitchable compounds, we report here a fluorescent probe (HTI-Q) for Cu2+ with excellent selectivity, high sensitivity, and a limit of detection (LOD) of ca. 0.02 μM. While the central carbon-carbon double bond of HTI-Q is photoisomerizable between the Z and E configurations, it is locked upon binding with Cu2+ into the E configuration, resulting in a large bathochromic shift (102 nm) and ratiometric fluorescence changes. Different sensing modes were demonstrated including in mixed solvents, a two-phase sensing system containing cation exchanger, and fluorescent nanoprobes containing a reference dye. The absorbance change of HTI-Q upon 470 nm light illumination also depended on the concentration of Cu2+. HTI-Q-based sensors were successfully applied to determine Cu2+ in real water samples with excellent recovery. Further, fluorescent nanoprobes incorporating HTI-Q were successfully applied to image endolysosomal Cu2+ changes upon external stimulation. [Display omitted] •A photoswitchable Cu2+ probe (HTI-Q) was proposed for the first time based on hemithioindigo.•HTI-Q offered tunable sensitivity, high selectivity, and several different optical sensing modes.•Nanoprobes containing HTI-Q were successfully applied for subcellular fluorescence imaging in the endolysosomes.