TY - JOUR A1 - Schwarze, Thomas A1 - Mertens, Monique A1 - Mueller, Peter A1 - Riemer, Janine A1 - Wessig, Pablo A1 - Holdt, Hans-Jürgen T1 - Highly K+-Selective Fluorescent Probes for Lifetime Sensing of K+ in Living Cells JF - Chemistry - a European journal N2 - The new K+-selective fluorescent probes 1 and 2 were obtained by Cu-I-catalyzed 1,3-dipolar azide alkyne cycloaddition (CuAAC) reactions of an alkyne-substituted [1,3]dioxolo[4,5-f][1,3]benzodioxole (DBD) ester fluorophore with azido-functionalized N-phenylaza-18-crown-6 ether and N-(o-isopropoxy) phenylaza-18-crown-6 ether, respectively. Probes 1 and 2 allow the detection of K+ in the presence of Na+ in water by fluorescence enhancement (2.2 for 1 at 2000mm K+ and 2.5 for 2 at 160mm K+). Fluorescence lifetime measurements in the absence and presence of K+ revealed bi-exponential decay kinetics with similar lifetimes, however with different proportions changing the averaged fluorescence decay times ((f(av))). For 1 a decrease of (f(av)) from 12.4 to 9.3ns and for 2 an increase from 17.8 to 21.8ns was observed. Variation of the substituent in ortho position of the aniline unit of the N-phenylaza-18-crown-6 host permits the modulation of the K-d value for a certain K+ concentration. For example, substitution of H in 1 by the isopropoxy group (2) decreased the K-d value from >300mm to 10mm. 2 was chosen for studying the efflux of K+ from human red blood cells (RBC). Upon addition of the Ca2+ ionophor ionomycin to a RBC suspension in a buffer containing Ca2+, the fluorescence of 2 slightly rose within 10min, however, after 120min a significant increase was observed. KW - electron transfer KW - fluorescence lifetime KW - fluorescent probes KW - living cells KW - potassium Y1 - 2017 U6 - https://doi.org/10.1002/chem.201704368 SN - 0947-6539 SN - 1521-3765 VL - 23 SP - 17186 EP - 17190 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Mueller, Holger A1 - Schmidt, Darya A1 - Riemer, Janine A1 - Holdt, Hans-Jürgen T1 - Design of Na+-Selective Fluorescent Probes: A Systematic Study of the Na+-Complex Stability and the Na+/K+ Selectivity in Acetonitrile and Water JF - Chemistry - a European journal N2 - There is a tremendous demand for highly Na+-selective fluoroionophores to monitor the top analyte Na+ in life science. Here, we report a systematic route to develop highly Na+/K+ selective fluorescent probes. Thus, we synthesized a set of fluoroionophores 1, 3, 4, 5, 8 and 9 (see Scheme 1) to investigate the Na+/K+ selectivity and Na(+-)complex stability in CH3CN and H2O. These Na+-probes bear different 15-crown-5 moieties to bind Na+ stronger than K+. In the set of the diethylaminocoumarin-substituted fluoroionophores 1-5, the following trend of fluorescence quenching 1 > 3 > 2 > 4 > 5 in CH3CN was observed. Therefore, the flexibility of the aza-15-crown-5 moieties in 1-4 determines the conjugation of the nitrogen lone pair with the aromatic ring. As a consequence, 1 showed in CH3CN the highest Na+-induced fluorescence enhancement (FE) by a factor of 46.5 and a weaker K+ induced FE of 3.7. The Na+-complex stability of 1-4 in CH3CN is enhanced in the following order of 2 > 4 > 3 > 1, assuming that the O-atom of the methoxy group in the ortho-position, as shown in 2, strengthened the Na+-complex formation. Furthermore, we found for the N( o-methoxyphenyl) aza-15-crown-5 substituted fluoroionophores 2, 8 and 9 in H2O, an enhanced Na+-complex stability in the following order 8 > 2 > 9 and an increased Na+/K+ selectivity in the reverse order 9 > 2 > 8. Notably, the Na+-induced FE of 8 (FEF = 10.9), 2 (FEF = 5.0) and 9 (FEF = 2.0) showed a similar trend associated with a decreased K+-induced FE [8 (FEF = 2.7) > 2 (FEF = 1.5) > 9 (FEF = 1.1)]. Here, the Na+-complex stability and Na+/K+ selectivity is also influenced by the fluorophore moiety. Thus, fluorescent probe 8 (K-d = 48 mm) allows high-contrast, sensitive, and selective Na+ measurements over extracellular K+ levels. A higher Na+/K+ selectivity showed fluorescent probe 9, but also a higher Kd value of 223 mm. Therefore, 9 is a suitable tool to measure Na+ concentrations up to 300 mm at a fluorescence emission of 614 nm. KW - crown compounds KW - fluorescence KW - fluorescent probes KW - potassium KW - sodium Y1 - 2017 U6 - https://doi.org/10.1002/chem.201605986 SN - 0947-6539 SN - 1521-3765 VL - 23 SP - 7255 EP - 7263 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Riemer, Janine A1 - Eidner, Sascha A1 - Holdt, Hans-Jürgen T1 - A Highly K+-Selective Two-Photon Fluorescent Probe JF - Chemistry - a European journal N2 - A highly K+-selective two-photon fluorescent probe for the in vitro monitoring of physiological K+ levels in the range of 1-100 mM is reported. The two-photon excited fluorescence (TPEF) probe shows a fluorescence enhancement (FE) by a factor of about three in the presence of 160 mM K+, independently of one-photon (OP, 430 nm) or two-photon (TP, 860 nm) excitation and comparable K+-induced FEs in the presence of competitive Na+ ions. The estimated dissociation constant (K-d) values in Na+-free solutions (K-d(OP)=(28 +/- 5) mM and K-d(TP)=(36 +/- 6) mM) and in combined K+/Na+ solutions (K-d(OP)=(38 +/- 8) mM and K-d(TP)=(46 +/- 25) mM) reflecting the high K+/Na+ selectivity of the fluorescent probe. The TP absorption cross-section (sigma(2PA)) of the TPEF probe+160 mMK(+) is 26 GM at 860 nm. Therefore, the TPEF probe is a suitable tool for the in vitro determination of K+. KW - click chemistry KW - fluorescence KW - fluorescent probes KW - potassium KW - two-photon Y1 - 2015 U6 - https://doi.org/10.1002/chem.201501473 SN - 0947-6539 SN - 1521-3765 VL - 21 IS - 32 SP - 11306 EP - 11310 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Riemer, Janine A1 - Müller, Holger A1 - John, Leonard A1 - Holdt, Hans-Jürgen A1 - Wessig, Pablo T1 - Na+ Selective Fluorescent Tools Based on Fluorescence Intensity Enhancements, Lifetime Changes, and on a Ratiometric Response JF - Chemistry - a European journal N2 - Over the years, we developed highly selective fluorescent probes for K+ in water, which show K+-induced fluorescence intensity enhancements, lifetime changes, or a ratiometric behavior at two emission wavelengths (cf. Scheme 1, K1-K4). In this paper, we introduce selective fluorescent probes for Na+ in water, which also show Na+ induced signal changes, which are analyzed by diverse fluorescence techniques. Initially, we synthesized the fluorescent probes 2, 4, 5, 6 and 10 for a fluorescence analysis by intensity enhancements at one wavelength by varying the Na+ responsive ionophore unit and the fluorophore moiety to adjust different K-d values for an intra- or extracellular Na+ analysis. Thus, we found that 2, 4 and 5 are Na+ selective fluorescent tools, which are able to measure physiologically important Na+ levels at wavelengths higher than 500 nm. Secondly, we developed the fluorescent probes 7 and 8 to analyze precise Na+ levels by fluorescence lifetime changes. Herein, only 8 (K-d=106 mm) is a capable fluorescent tool to measure Na+ levels in blood samples by lifetime changes. Finally, the fluorescent probe 9 was designed to show a Na+ induced ratiometric fluorescence behavior at two emission wavelengths. As desired, 9 (K-d=78 mm) showed a ratiometric fluorescence response towards Na+ ions and is a suitable tool to measure physiologically relevant Na+ levels by the intensity change of two emission wavelengths at 404 nm and 492 nm. KW - crown compounds KW - fluorescence lifetime KW - fluorescent probes KW - ratiometric KW - sodium Y1 - 2019 U6 - https://doi.org/10.1002/chem.201902536 SN - 0947-6539 SN - 1521-3765 VL - 25 IS - 53 SP - 12412 EP - 12422 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Schwarze, Thomas A1 - Riemer, Janine A1 - Müller, Holger A1 - John, Leonard A1 - Holdt, Hans‐Jürgen A1 - Wessig, Pablo T1 - Na+ Selective Fluorescent Tools Based on Fluorescence Intensity Enhancements, Lifetime Changes, and on a Ratiometric Response T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Over the years, we developed highly selective fluorescent probes for K+ in water, which show K+-induced fluorescence intensity enhancements, lifetime changes, or a ratiometric behavior at two emission wavelengths (cf. Scheme 1, K1-K4). In this paper, we introduce selective fluorescent probes for Na+ in water, which also show Na+ induced signal changes, which are analyzed by diverse fluorescence techniques. Initially, we synthesized the fluorescent probes 2, 4, 5, 6 and 10 for a fluorescence analysis by intensity enhancements at one wavelength by varying the Na+ responsive ionophore unit and the fluorophore moiety to adjust different K-d values for an intra- or extracellular Na+ analysis. Thus, we found that 2, 4 and 5 are Na+ selective fluorescent tools, which are able to measure physiologically important Na+ levels at wavelengths higher than 500 nm. Secondly, we developed the fluorescent probes 7 and 8 to analyze precise Na+ levels by fluorescence lifetime changes. Herein, only 8 (K-d=106 mm) is a capable fluorescent tool to measure Na+ levels in blood samples by lifetime changes. Finally, the fluorescent probe 9 was designed to show a Na+ induced ratiometric fluorescence behavior at two emission wavelengths. As desired, 9 (K-d=78 mm) showed a ratiometric fluorescence response towards Na+ ions and is a suitable tool to measure physiologically relevant Na+ levels by the intensity change of two emission wavelengths at 404 nm and 492 nm. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1136 KW - crown compounds KW - fluorescence lifetime KW - fluorescent probes KW - ratiometric KW - sodium Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-437482 SN - 1866-8372 IS - 1136 ER - TY - JOUR A1 - Schwarze, Thomas A1 - Schneider, Radu A1 - Riemer, Janine A1 - Holdt, Hans-Jürgen T1 - A Highly K+-Selective Fluorescent Probe - Tuning the K+-Complex Stability and the K+/Na+ Selectivity by Varying the Lariat-Alkoxy Unit of a Phenylaza[18]crown-6 Ionophore JF - Chemistry : an Asian journal ; an ACES journal N2 - A desirable goal is to synthesize easily accessible and highly K+/Na+-selective fluoroionophores to monitor physiological K+ levels in vitro and in vivo. Therefore, highly K+/Na+-selective ionophores have to be developed. Herein, we obtained in a sequence of only four synthetic steps a set of K+-responsive fluorescent probes 4, 5 and 6. In a systematic study, we investigated the influence of the alkoxy substitution in ortho position of the aniline moiety in -conjugated aniline-1,2,3-triazole-coumarin-fluoroionophores 4, 5 and 6 [R=MeO (4), EtO (5) and iPrO (6)] towards the K+-complex stability and K+/Na+ selectivity. The highest K+-complex stability showed fluoroionophore 4 with a dissociation constant K-d of 19mm, but the K-d value increases to 31mm in combined K+/Na+ solutions, indicating a poor K+/Na+ selectivity. By contrast, 6 showed even in the presence of competitive Na+ ions equal K-d values (K-d(K+)=45mm and K-d(K+/Na+)=45mm) and equal K+-induced fluorescence enhancement factors (FEFs=2.3). Thus, the fluorescent probe 6 showed an outstanding K+/Na+ selectivity and is a suitable fluorescent tool to measure physiological K+ levels in the range of 10-80mm in vitro. Further, the isopropoxy-substituted N-phenylaza[18]crown-6 ionophore in 6 is a highly K+-selective building block with a feasible synthetic route. KW - crown compounds KW - fluorescence KW - fluorescent probes KW - potassium KW - sodium Y1 - 2016 U6 - https://doi.org/10.1002/asia.201500956 SN - 1861-4728 SN - 1861-471X VL - 11 SP - 241 EP - 247 PB - Wiley-VCH CY - Weinheim ER -