Fluorescence of amphiphilic hemicyanine dyes without free double bonds

Ephardt, Heinz; Fromherz, Peter

doi:10.1021/j100119a048

Cited by 68 publications

(72 citation statements)

References 7 publications

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“…The voltage-sensitive dye dibutyl-naphtalene-butylsulfonato-isoquinolinium (BNBIQ) (Ephardt and Fromherz 1993;Fromherz and Müller 1993) was dissolved at a concentration of 4.3 mM in 15 mM cholic acid (Sigma) (Meyer et al 1997) in Lymnaea cell culture medium (Ridgway et al 1991). To stain cultured snail neurons, this stock solution was diluted 50-fold with medium and immediately added to the culture chamber, which was then incubated for 10 min in the dark and subsequently washed with medium.…”

Section: Optical Recordingmentioning

confidence: 99%

Effect of Neuritic Cables on Conductance Estimates for Remote Electrical Synapses

Prinz

Fromherz

2003

Journal of Neurophysiology

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Prinz, Astrid A. and Peter Fromherz. Effect of neuritic cables on conductance estimates for remote electrical synapses. J Neurophysiol 89: 2215-2224, 2003. First published December 18, 2002 10.1152/jn.00956.2002. The conductance of electrical synapses is usually estimated from voltage recordings at the neuronal somata under the assumption that each cell is isopotential. This approach neglects effects of intervening neurites. For a cell pair with unbranched neurites and an electrical synapse at their ends, we used cable theory to derive an analytical expression that relates the synaptic conductance to voltage recordings at the cell bodies and to the neurite properties. The equation implies that the conventional method significantly underestimates the actual synapse conductance if the neurite length is comparable to the electrotonic length constant and if the synaptic conductance is similar to the serial neurite conductance. For an experimental test, we cultured pairs of snail neurons on protein patterns, resulting in a geometry that matched the theoretical model. Using the isopotential theory, we estimated the synapse conductances and found them to be rather weak. To obtain the cable properties, we recorded spatiotemporal maps of signal propagation in the neurites using a voltage-sensitive dye. Fits of these maps to a passive cable model showed that the snail neurons are electrotonically rather compact. Given these features of our experimental system, the synaptic conductances derived with the nonisopotential model deviated from the estimates of the isopotential theory by about 13%. This discrepancy, although small, shows that even in electrotonically compact neurons coupled by weak synapses the impact of the neuritic cables on conductance estimates cannot be neglected. When applied to less compact and more strongly coupled cell pairs in vivo, our approach can supply the realistic estimates of synaptic conductances that are necessary for a better understanding of the role of electrical coupling in neural systems.

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Section: Optical Recordingmentioning

confidence: 99%

Effect of Neuritic Cables on Conductance Estimates for Remote Electrical Synapses

Prinz

Fromherz

2003

Journal of Neurophysiology

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“…The slight solvatochromic shifts found for dyes SI and S3 between different polysoaps are not useful for quantitative evaluation, keeping the spectral resolution of 2 nm in mind. This is surprisingly true as well for S4 and S5, considering the widespread use of cyanine dyes as solvatochromic probes [38,39]. But, in fact, the spectral differences are marginal, except for electrostatic effects: The cationic dye S4 shows a spectral shift of ca.…”

Section: Solvatochromic Effectsmentioning

confidence: 83%

“…Reference water P-18 P-19 P-20 21 22 Polysoap tail-end geometry P-l P-2 P-3 P-4 P-5 P-6 P-7 P-8 P-9 P-10 Co-llc Co-lld for this apparent inconsistency are not clear, but in fact, conclusions based on solvatochromism should be taken with great care considering recent studies on cyanine probes [39]. Only in the case of azodye S2 are the solvatochromic effects more notable, though difficult to interpret.…”

Section: Solubilizing Agentmentioning

confidence: 99%

Solubilization by polysoaps

Anton

Laschewsky

1994

Colloid Polym Sci

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Abstract:The aqueous solubilization power of several series of micellar homopolymers and copolymers ("polysoaps") is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect to the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes.

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“…("qualitative solubilization"). The majority of such studies employs dye probes whose spectral properties are sensitive to the environment of the chromophore [20,[362][363][364][365][366]. The second, less frequent type of studies is focussed on the solubilization capacity of the polysoaps ("quantitative solubilization").…”

Section: Solubilizationmentioning

confidence: 99%

“…Solvatochromic shifts of absorbance and emission spectra are particularly simple to detect. It should be noted however that extent and magnitude of the solvatochromic shifts are often difficult to rationalize [343,364,366]. Furthermore, shifts due to solubilization by hydrophobic aggregates may be hard to distinguish from effects due to specific (e.g.…”

Section: Solubilization Of Probe Moleculesmentioning

confidence: 99%

Molecular concepts, self-organisation and properties of polysoaps

Laschewsky

Polysoaps/Stabilizers/Nitrogen-15 NMR

223

126

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The article reviews water-soluble polymers characterized by surfactant side chains, and related amphiphilic polymers. Various synthetic approaches are presented, and rules for useful molecular architectures are given. Models for the self-organization of such polymers in water are presented comparing them with the micellization of low molecular weight surfactants. Highlighting key properties of aqueous polysoap solutions such as viscosity, surface tension and solubilization power, some structure-property relationships are established. Further, the formation of mesophases and of superstructures in bulk is addressed. Finally, the functionalization of polysoaps, and potential applications are discussed.

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Fluorescence of amphiphilic hemicyanine dyes without free double bonds

Cited by 68 publications

References 7 publications

Effect of Neuritic Cables on Conductance Estimates for Remote Electrical Synapses

Effect of Neuritic Cables on Conductance Estimates for Remote Electrical Synapses

Solubilization by polysoaps

Molecular concepts, self-organisation and properties of polysoaps

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