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Johannes Bohrmann - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical gradients are involved in regulating cytoskeletal patterns during epithelial morphogenesis in the Drosophila ovary
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:Background During Drosophila oogenesis, the follicular epithelium differentiates into several morphologically distinct follicle-cell populations. Characteristic bioelectrical properties make this tissue a suitable model system for studying connections between electrochemical signals and the organisation of the cytoskeleton. Recently, we have described stage-specific transcellular antero-posterior and dorso-ventral gradients of intracellular pH (pH_i) and membrane potential (V_mem) depending on the asymmetrical distribution and/or activity of various ion-transport mechanisms. In the present study, we analysed the patterns of basal microfilaments (bMF) and microtubules (MT) in relation to electrochemical signals. Results The bMF- and MT-patterns in developmental stages 8 to 12 were visualised using labelled phalloidin and an antibody against acetylated α-tubulin as well as follicle-cell specific expression of GFP-actin and GFP-α-tubulin. Obviously, stage-specific changes of the pH_i- and V_mem-gradients correlate with modifications of the bMF- and MT-organisation. In order to test whether cytoskeletal modifications depend directly on bioelectrical changes, we used inhibitors of ion-transport mechanisms that have previously been shown to modify pH_i and V_mem as well as the respective gradients. We inhibited, in stage 10b, Na^+/H^+-exchangers and Na^+-channels with amiloride, V-ATPases with bafilomycin, ATP-sensitive K^+-channels with glibenclamide, voltage-dependent L-type Ca^2+-channels with verapamil, Cl^−-channels with 9-Anthroic Acid and Na^+/K^+/2Cl^−-cotransporters with furosemide, respectively. The correlations between pH_i, V_mem, bMF and MT observed in different follicle-cell types are in line with the correlations resulting from the inhibition experiments. While relative alkalisation and/or hyperpolarisation stabilised the parallel transversal alignment of bMF, Acidification led to increasing disorder and to condensations of bMF. On the other hand, relative Acidification as well as hyperpolarisation stabilised the longitudinal orientation of MT, whereas alkalisation led to loss of this arrangement and to partial disintegration of MT. Conclusions We conclude that the pH_i- and V_mem-changes induced by inhibitors of ion-transport mechanisms simulate bioelectrical changes occurring naturally and leading to the cytoskeletal changes observed during differentiation of the follicle-cell epithelium. Therefore, gradual modifications of electrochemical signals can serve as physiological means to regulate cell and tissue architecture by modifying cytoskeletal patterns.
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Electrochemical gradients are involved in regulating cytoskeletal patterns during epithelial morphogenesis in the Drosophila ovary.
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:During Drosophila oogenesis, the follicular epithelium differentiates into several morphologically distinct follicle-cell populations. Characteristic bioelectrical properties make this tissue a suitable model system for studying connections between electrochemical signals and the organisation of the cytoskeleton. Recently, we have described stage-specific transcellular antero-posterior and dorso-ventral gradients of intracellular pH (pHi) and membrane potential (Vmem) depending on the asymmetrical distribution and/or activity of various ion-transport mechanisms. In the present study, we analysed the patterns of basal microfilaments (bMF) and microtubules (MT) in relation to electrochemical signals. The bMF- and MT-patterns in developmental stages 8 to 12 were visualised using labelled phalloidin and an antibody against acetylated α-tubulin as well as follicle-cell specific expression of GFP-actin and GFP-α-tubulin. Obviously, stage-specific changes of the pHi- and Vmem-gradients correlate with modifications of the bMF- and MT-organisation. In order to test whether cytoskeletal modifications depend directly on bioelectrical changes, we used inhibitors of ion-transport mechanisms that have previously been shown to modify pHi and Vmem as well as the respective gradients. We inhibited, in stage 10b, Na+/H+-exchangers and Na+-channels with amiloride, V-ATPases with bafilomycin, ATP-sensitive K+-channels with glibenclamide, voltage-dependent L-type Ca2+-channels with verapamil, Cl−-channels with 9-Anthroic Acid and Na+/K+/2Cl−-cotransporters with furosemide, respectively. The correlations between pHi, Vmem, bMF and MT observed in different follicle-cell types are in line with the correlations resulting from the inhibition experiments. While relative alkalisation and/or hyperpolarisation stabilised the parallel transversal alignment of bMF, Acidification led to increasing disorder and to condensations of bMF. On the other hand, relative Acidification as well as hyperpolarisation stabilised the longitudinal orientation of MT, whereas alkalisation led to loss of this arrangement and to partial disintegration of MT. We conclude that the pHi- and Vmem-changes induced by inhibitors of ion-transport mechanisms simulate bioelectrical changes occurring naturally and leading to the cytoskeletal changes observed during differentiation of the follicle-cell epithelium. Therefore, gradual modifications of electrochemical signals can serve as physiological means to regulate cell and tissue architecture by modifying cytoskeletal patterns.
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Electrochemical patterns during Drosophila oogenesis: ion-transport mechanisms generate stage-specific gradients of pH and membrane potential in the follicle-cell epithelium
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:Alterations of bioelectrical properties of cells and tissues are known to function as wide-ranging signals during development, regeneration and wound-healing in several species. The Drosophila follicle-cell epithelium provides an appropriate model system for studying the potential role of electrochemical signals, like intracellular pH (pHi) and membrane potential (Vmem), during development. Therefore, we analysed stage-specific gradients of pHi and Vmem as well as their dependence on specific ion-transport mechanisms. Using fluorescent indicators, we found distinct alterations of pHi- and Vmem-patterns during stages 8 to 12 of oogenesis. To determine the roles of relevant ion-transport mechanisms in regulating pHi and Vmem and in establishing stage-specific antero-posterior and dorso-ventral gradients, we used inhibitors of Na+/H+-exchangers and Na+-channels (amiloride), V-ATPases (bafilomycin), ATP-sensitive K+-channels (glibenclamide), voltage-dependent L-type Ca2+-channels (verapamil), Cl−-channels (9-Anthroic Acid) and Na+/K+/2Cl−-cotransporters (furosemide). Either pHi or Vmem or both parameters were affected by each tested inhibitor. While the inhibition of Na+/H+-exchangers (NHE) and amiloride-sensitive Na+-channels or of V-ATPases resulted in relative Acidification, inhibiting the other ion-transport mechanisms led to relative alkalisation. The most prominent effects on pHi were obtained by inhibiting Na+/K+/2Cl−-cotransporters or ATP-sensitive K+-channels. Vmem was most efficiently hyperpolarised by inhibiting voltage-dependent L-type Ca2+-channels or ATP-sensitive K+-channels, whereas the impact of the other ion-transport mechanisms was smaller. In case of very prominent effects of inhibitors on pHi and/or Vmem, we also found strong influences on the antero-posterior and dorso-ventral pHi- and/or Vmem-gradients. For example, inhibiting ATP-sensitive K+-channels strongly enhanced both pHi-gradients (increasing alkalisation) and reduced both Vmem-gradients (increasing hyperpolarisation). Similarly, inhibiting Na+/K+/2Cl−-cotransporters strongly enhanced both pHi-gradients and reduced the antero-posterior Vmem-gradient. To minor extents, both pHi-gradients were enhanced and both Vmem-gradients were reduced by inhibiting voltage-dependent L-type Ca2+-channels, whereas only both pHi-gradients were reduced (increasing Acidification) by inhibiting V-ATPases or NHE and Na+-channels. Our data show that in the Drosophila follicle-cell epithelium stage-specific pHi- and Vmem-gradients develop which result from the activity of several ion-transport mechanisms. These gradients are supposed to represent important bioelectrical cues during oogenesis, e.g., by serving as electrochemical prepatterns in modifying cell polarity and cytoskeletal organisation.
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Electrochemical patterns during Drosophila oogenesis: ion-transport mechanisms generate stage-specific gradients of pH and membrane potential in the follicle-cell epithelium
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:Background Alterations of bioelectrical properties of cells and tissues are known to function as wide-ranging signals during development, regeneration and wound-healing in several species. The Drosophila follicle-cell epithelium provides an appropriate model system for studying the potential role of electrochemical signals, like intracellular pH (pH_i) and membrane potential (V_mem), during development. Therefore, we analysed stage-specific gradients of pH_i and V_mem as well as their dependence on specific ion-transport mechanisms. Results Using fluorescent indicators, we found distinct alterations of pH_i- and V_mem-patterns during stages 8 to 12 of oogenesis. To determine the roles of relevant ion-transport mechanisms in regulating pH_i and V_mem and in establishing stage-specific antero-posterior and dorso-ventral gradients, we used inhibitors of Na^+/H^+-exchangers and Na^+-channels (amiloride), V-ATPases (bafilomycin), ATP-sensitive K^+-channels (glibenclamide), voltage-dependent L-type Ca^2+-channels (verapamil), Cl^−-channels (9-Anthroic Acid) and Na^+/K^+/2Cl^−-cotransporters (furosemide). Either pH_i or V_mem or both parameters were affected by each tested inhibitor. While the inhibition of Na^+/H^+-exchangers (NHE) and amiloride-sensitive Na^+-channels or of V-ATPases resulted in relative Acidification, inhibiting the other ion-transport mechanisms led to relative alkalisation. The most prominent effects on pH_i were obtained by inhibiting Na^+/K^+/2Cl^−-cotransporters or ATP-sensitive K^+-channels. V_mem was most efficiently hyperpolarised by inhibiting voltage-dependent L-type Ca^2+-channels or ATP-sensitive K^+-channels, whereas the impact of the other ion-transport mechanisms was smaller. In case of very prominent effects of inhibitors on pH_i and/or V_mem, we also found strong influences on the antero-posterior and dorso-ventral pH_i- and/or V_mem-gradients. For example, inhibiting ATP-sensitive K^+-channels strongly enhanced both pH_i-gradients (increasing alkalisation) and reduced both V_mem-gradients (increasing hyperpolarisation). Similarly, inhibiting Na^+/K^+/2Cl^−-cotransporters strongly enhanced both pH_i-gradients and reduced the antero-posterior V_mem-gradient. To minor extents, both pH_i-gradients were enhanced and both V_mem-gradients were reduced by inhibiting voltage-dependent L-type Ca^2+-channels, whereas only both pH_i-gradients were reduced (increasing Acidification) by inhibiting V-ATPases or NHE and Na^+-channels. Conclusions Our data show that in the Drosophila follicle-cell epithelium stage-specific pH_i- and V_mem-gradients develop which result from the activity of several ion-transport mechanisms. These gradients are supposed to represent important bioelectrical cues during oogenesis, e.g., by serving as electrochemical prepatterns in modifying cell polarity and cytoskeletal organisation.
Isabel Weiß - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical gradients are involved in regulating cytoskeletal patterns during epithelial morphogenesis in the Drosophila ovary
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:Background During Drosophila oogenesis, the follicular epithelium differentiates into several morphologically distinct follicle-cell populations. Characteristic bioelectrical properties make this tissue a suitable model system for studying connections between electrochemical signals and the organisation of the cytoskeleton. Recently, we have described stage-specific transcellular antero-posterior and dorso-ventral gradients of intracellular pH (pH_i) and membrane potential (V_mem) depending on the asymmetrical distribution and/or activity of various ion-transport mechanisms. In the present study, we analysed the patterns of basal microfilaments (bMF) and microtubules (MT) in relation to electrochemical signals. Results The bMF- and MT-patterns in developmental stages 8 to 12 were visualised using labelled phalloidin and an antibody against acetylated α-tubulin as well as follicle-cell specific expression of GFP-actin and GFP-α-tubulin. Obviously, stage-specific changes of the pH_i- and V_mem-gradients correlate with modifications of the bMF- and MT-organisation. In order to test whether cytoskeletal modifications depend directly on bioelectrical changes, we used inhibitors of ion-transport mechanisms that have previously been shown to modify pH_i and V_mem as well as the respective gradients. We inhibited, in stage 10b, Na^+/H^+-exchangers and Na^+-channels with amiloride, V-ATPases with bafilomycin, ATP-sensitive K^+-channels with glibenclamide, voltage-dependent L-type Ca^2+-channels with verapamil, Cl^−-channels with 9-Anthroic Acid and Na^+/K^+/2Cl^−-cotransporters with furosemide, respectively. The correlations between pH_i, V_mem, bMF and MT observed in different follicle-cell types are in line with the correlations resulting from the inhibition experiments. While relative alkalisation and/or hyperpolarisation stabilised the parallel transversal alignment of bMF, Acidification led to increasing disorder and to condensations of bMF. On the other hand, relative Acidification as well as hyperpolarisation stabilised the longitudinal orientation of MT, whereas alkalisation led to loss of this arrangement and to partial disintegration of MT. Conclusions We conclude that the pH_i- and V_mem-changes induced by inhibitors of ion-transport mechanisms simulate bioelectrical changes occurring naturally and leading to the cytoskeletal changes observed during differentiation of the follicle-cell epithelium. Therefore, gradual modifications of electrochemical signals can serve as physiological means to regulate cell and tissue architecture by modifying cytoskeletal patterns.
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Electrochemical gradients are involved in regulating cytoskeletal patterns during epithelial morphogenesis in the Drosophila ovary.
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:During Drosophila oogenesis, the follicular epithelium differentiates into several morphologically distinct follicle-cell populations. Characteristic bioelectrical properties make this tissue a suitable model system for studying connections between electrochemical signals and the organisation of the cytoskeleton. Recently, we have described stage-specific transcellular antero-posterior and dorso-ventral gradients of intracellular pH (pHi) and membrane potential (Vmem) depending on the asymmetrical distribution and/or activity of various ion-transport mechanisms. In the present study, we analysed the patterns of basal microfilaments (bMF) and microtubules (MT) in relation to electrochemical signals. The bMF- and MT-patterns in developmental stages 8 to 12 were visualised using labelled phalloidin and an antibody against acetylated α-tubulin as well as follicle-cell specific expression of GFP-actin and GFP-α-tubulin. Obviously, stage-specific changes of the pHi- and Vmem-gradients correlate with modifications of the bMF- and MT-organisation. In order to test whether cytoskeletal modifications depend directly on bioelectrical changes, we used inhibitors of ion-transport mechanisms that have previously been shown to modify pHi and Vmem as well as the respective gradients. We inhibited, in stage 10b, Na+/H+-exchangers and Na+-channels with amiloride, V-ATPases with bafilomycin, ATP-sensitive K+-channels with glibenclamide, voltage-dependent L-type Ca2+-channels with verapamil, Cl−-channels with 9-Anthroic Acid and Na+/K+/2Cl−-cotransporters with furosemide, respectively. The correlations between pHi, Vmem, bMF and MT observed in different follicle-cell types are in line with the correlations resulting from the inhibition experiments. While relative alkalisation and/or hyperpolarisation stabilised the parallel transversal alignment of bMF, Acidification led to increasing disorder and to condensations of bMF. On the other hand, relative Acidification as well as hyperpolarisation stabilised the longitudinal orientation of MT, whereas alkalisation led to loss of this arrangement and to partial disintegration of MT. We conclude that the pHi- and Vmem-changes induced by inhibitors of ion-transport mechanisms simulate bioelectrical changes occurring naturally and leading to the cytoskeletal changes observed during differentiation of the follicle-cell epithelium. Therefore, gradual modifications of electrochemical signals can serve as physiological means to regulate cell and tissue architecture by modifying cytoskeletal patterns.
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Electrochemical patterns during Drosophila oogenesis: ion-transport mechanisms generate stage-specific gradients of pH and membrane potential in the follicle-cell epithelium
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:Alterations of bioelectrical properties of cells and tissues are known to function as wide-ranging signals during development, regeneration and wound-healing in several species. The Drosophila follicle-cell epithelium provides an appropriate model system for studying the potential role of electrochemical signals, like intracellular pH (pHi) and membrane potential (Vmem), during development. Therefore, we analysed stage-specific gradients of pHi and Vmem as well as their dependence on specific ion-transport mechanisms. Using fluorescent indicators, we found distinct alterations of pHi- and Vmem-patterns during stages 8 to 12 of oogenesis. To determine the roles of relevant ion-transport mechanisms in regulating pHi and Vmem and in establishing stage-specific antero-posterior and dorso-ventral gradients, we used inhibitors of Na+/H+-exchangers and Na+-channels (amiloride), V-ATPases (bafilomycin), ATP-sensitive K+-channels (glibenclamide), voltage-dependent L-type Ca2+-channels (verapamil), Cl−-channels (9-Anthroic Acid) and Na+/K+/2Cl−-cotransporters (furosemide). Either pHi or Vmem or both parameters were affected by each tested inhibitor. While the inhibition of Na+/H+-exchangers (NHE) and amiloride-sensitive Na+-channels or of V-ATPases resulted in relative Acidification, inhibiting the other ion-transport mechanisms led to relative alkalisation. The most prominent effects on pHi were obtained by inhibiting Na+/K+/2Cl−-cotransporters or ATP-sensitive K+-channels. Vmem was most efficiently hyperpolarised by inhibiting voltage-dependent L-type Ca2+-channels or ATP-sensitive K+-channels, whereas the impact of the other ion-transport mechanisms was smaller. In case of very prominent effects of inhibitors on pHi and/or Vmem, we also found strong influences on the antero-posterior and dorso-ventral pHi- and/or Vmem-gradients. For example, inhibiting ATP-sensitive K+-channels strongly enhanced both pHi-gradients (increasing alkalisation) and reduced both Vmem-gradients (increasing hyperpolarisation). Similarly, inhibiting Na+/K+/2Cl−-cotransporters strongly enhanced both pHi-gradients and reduced the antero-posterior Vmem-gradient. To minor extents, both pHi-gradients were enhanced and both Vmem-gradients were reduced by inhibiting voltage-dependent L-type Ca2+-channels, whereas only both pHi-gradients were reduced (increasing Acidification) by inhibiting V-ATPases or NHE and Na+-channels. Our data show that in the Drosophila follicle-cell epithelium stage-specific pHi- and Vmem-gradients develop which result from the activity of several ion-transport mechanisms. These gradients are supposed to represent important bioelectrical cues during oogenesis, e.g., by serving as electrochemical prepatterns in modifying cell polarity and cytoskeletal organisation.
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Electrochemical patterns during Drosophila oogenesis: ion-transport mechanisms generate stage-specific gradients of pH and membrane potential in the follicle-cell epithelium
BMC Developmental Biology, 2019Co-Authors: Isabel Weiß, Johannes BohrmannAbstract:Background Alterations of bioelectrical properties of cells and tissues are known to function as wide-ranging signals during development, regeneration and wound-healing in several species. The Drosophila follicle-cell epithelium provides an appropriate model system for studying the potential role of electrochemical signals, like intracellular pH (pH_i) and membrane potential (V_mem), during development. Therefore, we analysed stage-specific gradients of pH_i and V_mem as well as their dependence on specific ion-transport mechanisms. Results Using fluorescent indicators, we found distinct alterations of pH_i- and V_mem-patterns during stages 8 to 12 of oogenesis. To determine the roles of relevant ion-transport mechanisms in regulating pH_i and V_mem and in establishing stage-specific antero-posterior and dorso-ventral gradients, we used inhibitors of Na^+/H^+-exchangers and Na^+-channels (amiloride), V-ATPases (bafilomycin), ATP-sensitive K^+-channels (glibenclamide), voltage-dependent L-type Ca^2+-channels (verapamil), Cl^−-channels (9-Anthroic Acid) and Na^+/K^+/2Cl^−-cotransporters (furosemide). Either pH_i or V_mem or both parameters were affected by each tested inhibitor. While the inhibition of Na^+/H^+-exchangers (NHE) and amiloride-sensitive Na^+-channels or of V-ATPases resulted in relative Acidification, inhibiting the other ion-transport mechanisms led to relative alkalisation. The most prominent effects on pH_i were obtained by inhibiting Na^+/K^+/2Cl^−-cotransporters or ATP-sensitive K^+-channels. V_mem was most efficiently hyperpolarised by inhibiting voltage-dependent L-type Ca^2+-channels or ATP-sensitive K^+-channels, whereas the impact of the other ion-transport mechanisms was smaller. In case of very prominent effects of inhibitors on pH_i and/or V_mem, we also found strong influences on the antero-posterior and dorso-ventral pH_i- and/or V_mem-gradients. For example, inhibiting ATP-sensitive K^+-channels strongly enhanced both pH_i-gradients (increasing alkalisation) and reduced both V_mem-gradients (increasing hyperpolarisation). Similarly, inhibiting Na^+/K^+/2Cl^−-cotransporters strongly enhanced both pH_i-gradients and reduced the antero-posterior V_mem-gradient. To minor extents, both pH_i-gradients were enhanced and both V_mem-gradients were reduced by inhibiting voltage-dependent L-type Ca^2+-channels, whereas only both pH_i-gradients were reduced (increasing Acidification) by inhibiting V-ATPases or NHE and Na^+-channels. Conclusions Our data show that in the Drosophila follicle-cell epithelium stage-specific pH_i- and V_mem-gradients develop which result from the activity of several ion-transport mechanisms. These gradients are supposed to represent important bioelectrical cues during oogenesis, e.g., by serving as electrochemical prepatterns in modifying cell polarity and cytoskeletal organisation.
Isiah M Warner - One of the best experts on this subject based on the ideXlab platform.
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fluorescence spectral study of 9 acridinecarboxylic Acid and its methyl ester understanding the unusual fluorescence behavior of 9 Anthroic Acid
Journal of Physical Chemistry A, 1997Co-Authors: Judson L Haynes, Isiah M Warner, Asit K ChandraAbstract:The absorption and fluorescence spectral characteristics of 9-acridinecarboxylic Acid (9-ACA) and 9-(methoxycarbonyl)acridine (9-MCA) were studied in a series of organic solvents and in aqueous solutions. Fluorescence quantum yields (Φf) and lifetimes (τf) of the compounds were measured in these solvents. Unlike 9-Anthroic Acid (9-AA), as reported in the literature, no large Stokes-shifted fluorescence emission band was observed for 9-ACA and 9-MCA in neutral organic solvents or water. The absence of large Stokes-shifted emission in the case of 9-ACA and 9-MCA suggests the existence of a charge-transfer emitting state in 9-AA in which the carboxyl group is nearly coplanar with the aromatic ring. The Φf values for both compounds increase as a function of hydrogen-bonding capacity of the solvents. In near neutral to slightly Acidic solutions, 9-ACA exists mainly in the zwitterionic form. Both 9-ACA and 9-MCA form monoprotonated species in moderately concentrated Acid solutions. The Acidium cation of 9-AA fo...
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use of cyclodextrins and fluorescence spectroscopy to probe the dual fluorescence of 9 Anthroic Acid
The Journal of Physical Chemistry, 1996Co-Authors: Rezik A Agbaria, Michelle T Butterfield, Isiah M WarnerAbstract:We report here a study of 9-Anthroic Acid (9-anthracenecarboxylic Acid) in aqueous and solid solutions of β-cyclodextrin in which we demonstrate the use of cyclodextrins, in combination with fluorescence spectroscopy, to probe molecular processes. The dual fluorescence of 9-Anthroic Acid is dependent on the pH, the solvent, and the concentration of the Acid. The origin of this dual fluorescence has been a point of controversy for many years. The small cavity of β-cyclodextrin cannot include more than one 9-Anthroic Acid molecule and is used in this study to distinguish between a unimolecular and bimolecular model for the dual fluorescence of 9-Anthroic Acid. The formation of a host/guest inclusion complex of 9-Anthroic Acid with β-cyclodextrin should reduce the presence of dimers, and as a result, a decrease in the corresponding fluorescence intensity would be expected if aggregation is the source of the observed dual fluorescence. However, we have observed that the broad fluorescence, which some have pre...
Asit K Chandra - One of the best experts on this subject based on the ideXlab platform.
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fluorescence spectral study of 9 acridinecarboxylic Acid and its methyl ester understanding the unusual fluorescence behavior of 9 Anthroic Acid
Journal of Physical Chemistry A, 1997Co-Authors: Judson L Haynes, Isiah M Warner, Asit K ChandraAbstract:The absorption and fluorescence spectral characteristics of 9-acridinecarboxylic Acid (9-ACA) and 9-(methoxycarbonyl)acridine (9-MCA) were studied in a series of organic solvents and in aqueous solutions. Fluorescence quantum yields (Φf) and lifetimes (τf) of the compounds were measured in these solvents. Unlike 9-Anthroic Acid (9-AA), as reported in the literature, no large Stokes-shifted fluorescence emission band was observed for 9-ACA and 9-MCA in neutral organic solvents or water. The absence of large Stokes-shifted emission in the case of 9-ACA and 9-MCA suggests the existence of a charge-transfer emitting state in 9-AA in which the carboxyl group is nearly coplanar with the aromatic ring. The Φf values for both compounds increase as a function of hydrogen-bonding capacity of the solvents. In near neutral to slightly Acidic solutions, 9-ACA exists mainly in the zwitterionic form. Both 9-ACA and 9-MCA form monoprotonated species in moderately concentrated Acid solutions. The Acidium cation of 9-AA fo...
Rezik A Agbaria - One of the best experts on this subject based on the ideXlab platform.
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use of cyclodextrins and fluorescence spectroscopy to probe the dual fluorescence of 9 Anthroic Acid
The Journal of Physical Chemistry, 1996Co-Authors: Rezik A Agbaria, Michelle T Butterfield, Isiah M WarnerAbstract:We report here a study of 9-Anthroic Acid (9-anthracenecarboxylic Acid) in aqueous and solid solutions of β-cyclodextrin in which we demonstrate the use of cyclodextrins, in combination with fluorescence spectroscopy, to probe molecular processes. The dual fluorescence of 9-Anthroic Acid is dependent on the pH, the solvent, and the concentration of the Acid. The origin of this dual fluorescence has been a point of controversy for many years. The small cavity of β-cyclodextrin cannot include more than one 9-Anthroic Acid molecule and is used in this study to distinguish between a unimolecular and bimolecular model for the dual fluorescence of 9-Anthroic Acid. The formation of a host/guest inclusion complex of 9-Anthroic Acid with β-cyclodextrin should reduce the presence of dimers, and as a result, a decrease in the corresponding fluorescence intensity would be expected if aggregation is the source of the observed dual fluorescence. However, we have observed that the broad fluorescence, which some have pre...
