Rhodol-based thallium sensors for cellular imaging of potassium channel activity

• Published in: Organic & biomolecular chemistry Vol. 16; no. 31; pp. 5575 - 5579
• Main Authors: Dutter, Brendan F., Ender, Anna, Sulikowski, Gary A., Weaver, C. David
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 08.08.2018; Royal Society of Chemistry
• Subjects: Assaying; Channel gating; Chemistry; Chemistry, Organic; Dyes; Emission spectra; Excitation; Excitation spectra; Fluorescein; Fluorescence; Fluorescent Dyes - chemistry; HEK293 Cells; Humans; Methylation; Microscopy, Confocal - methods; Optical Imaging - methods; Permeability; pH effects; Physical Sciences; Potassium; Potassium Channels - metabolism; Science & Technology; Sensors; Spectrometry, Fluorescence - methods; Thallium; Thallium - analysis; Thallium - metabolism; Wavelengths; Xanthones - chemistry; CELLS; CHEMOSENSOR; ASSAY; FLUOROPHORES; ROLES; DISEASE; MECHANISMS; HEALTH; DERIVATIVES; ZINC
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/c8ob01098f

Thallium (Tl+) flux assays enable imaging of potassium (K+) channel activity in cells and tissues by exploiting the permeability of K+ channels to Tl+ coupled with a fluorescent Tl+ sensitive dye. Common Tl+ sensing dyes utilize fluorescein as the fluorophore though fluorescein exhibits certain undesirable properties in these assays including short excitation wavelengths and pH sensitivity. To overcome these drawbacks, the replacement of fluorescein with rhodols was investigated. A library of 13 rhodol-based Tl+ sensors was synthesized and their properties and performance in Tl+ flux assays evaluated. The dimethyl rhodol Tl+ sensor emerged as the best of the series and performed comparably to fluorescein-based sensors while demonstrating greater pH tolerance in the physiological range and excitation and emission spectra 30 nm red-shifted from fluorescein.