biostudies-literatureUnknown10Sato SPotassium-sensing oligonucleotide, PSO, a conjugate of a quadruplex structure-forming oligonucleotide with a peptide incorporating a Förster Resonance Energy Transfer (FRET) chromophore pair, has been developed for fluorescent detection of potassium ion (K⁺) in aqueous medium. PSO <b>1</b> could be introduced into cells for real-time imaging of cytoplasmic K⁺ concentrations. To perform fluorescent imaging of K⁺ on the cell surface, we synthesized twelve PSO derivatives with different types of peptide types and lengths, and oligonucleotide sequences including thrombin-binding aptamer (TBA) sequences with FAM and TAMRA as a FRET chromophore pair, and evaluated their performance. <b>1</b> was shown to respond selectively to K⁺, not to most ions present <i>in vivo</i>, and to show reciprocal fluorescence changes in response to K⁺ concentration. For the peptide chains and oligonucleotide sequences examined in this study, the PSO derivatives had <i>K</i> _d values for K⁺ in the range of 5-30 mM. All PSO derivatives showed high K⁺ selectivity even in the presence of excess Na⁺. The PSO derivatives were successfully localized to the cell surface by biotinylated concanavalin A (ConA) or sulfo-NHS-biotin <i>via</i> streptavidin (StAv). Fluorescence imaging of extracellular K⁺ upon addition of apoptosis inducers was successfully achieved by <b>1</b> localized to the cell surface.Frontiers in chemistry922094https://www.ebi.ac.uk/biostudies/studies/S-EPMC9306769biostudies-literatureFluorescence Imaging of Extracellular Potassium Ion Using Potassium Sensing Oligonucleotide.PMC9306769Sota KSato SMatsuda TSakamoto NNagai TSueda STakenaka SUdo AOhzawa SfalseFluorescence Imaging of Extracellular Potassium Ion Using Potassium Sensing Oligonucleotide.Potassium-sensing oligonucleotide, PSO, a conjugate of a quadruplex structure-forming oligonucleotide with a peptide incorporating a Förster Resonance Energy Transfer (FRET) chromophore pair, has been developed for fluorescent detection of potassium ion (K⁺) in aqueous medium. PSO <b>1</b> could be introduced into cells for real-time imaging of cytoplasmic K⁺ concentrations. To perform fluorescent imaging of K⁺ on the cell surface, we synthesized twelve PSO derivatives with different types of peptide types and lengths, and oligonucleotide sequences including thrombin-binding aptamer (TBA) sequences with FAM and TAMRA as a FRET chromophore pair, and evaluated their performance. <b>1</b> was shown to respond selectively to K⁺, not to most ions present <i>in vivo</i>, and to show reciprocal fluorescence changes in response to K⁺ concentration. For the peptide chains and oligonucleotide sequences examined in this study, the PSO derivatives had <i>K</i> _d values for K⁺ in the range of 5-30 mM. All PSO derivatives showed high K⁺ selectivity even in the presence of excess Na⁺. The PSO derivatives were successfully localized to the cell surface by biotinylated concanavalin A (ConA) or sulfo-NHS-biotin <i>via</i> streptavidin (StAv). Fluorescence imaging of extracellular K⁺ upon addition of apoptosis inducers was successfully achieved by <b>1</b> localized to the cell surface.2022-01-01T00:00:00Z20222025-04-04T10:47:27.328Z2025-04-04T10:47:27.328ZS-EPMC93067693587303610.3389/fchem.2022.922094