Deduction of micellar shape from angular dissymmetry measurements of light scattered from aqueous sodium dodecyl sulfate solutions at high sodium chloride concentrations

Young, Charles Y.; Missel, Paul J.; Mazer, Norman A.; Benedek, George B.; Carey, Martin C.

doi:10.1021/j100501a011

Cited by 192 publications

(127 citation statements)

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“…From the static light scattering 14 (SLS) we deduced that at least the largest structures formed by the poly-APS adopt a spherical configuration. In Figure 3 we report the experimental points and the theoretical fit with three alternative spatial arrangements: the spherical shape seemed to be the most reliable structure adopted by a polymer aggregate in solution.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Anticholinesterase-Active 3-Alkylpyridinium Polymers from the Marine Sponge Reniera sarai in Aqueous Solutions

et al. 1997

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From the marine sponge Reniera sarai 3-alkylpyridinium oligomers and polymers have been isolated. 3-Alkylpyridinium polymers are potent anticholinesterase agents; in addition, they show hemolytic and cytotoxic activities. Oligomers with a molecular weight lower than 3000 Da do not possess any significant activity. We report structural characterization of 3-alkylpyridinium polymers and their behavior in aqueous solutions. We found that biologically active polymers are composed of head-to-tail 3-alkylpyridinium units. According to MALDI-TOF spectrometry two species of polymers exist, the smaller with a molecular weight of 5520 Da and the larger with a molecular weight of 18 900 Da. Both polymers are soluble only in water, while low molecular oligomers are readily soluble in organic solvents. Polymers form large water-dissolved supramolecular structures with an average hydrodynamic radius of 23 ( 2 nm and, therefore, cannot be separated with size-exclusion chromatography.Recently, several 3-alkylpyridinium compounds endowed with potent biological activities have been isolated from various marine sponges. These compounds have been described as constituted of 3-alkylpyridinium salt subunits (APS). The 3-alkyl chain is bound headto-tail to the nitrogen of the adjacent subunit as in (a) epidermal growth factor (EFG)-active factors, constituted of oligomers built on straight C 8 alkyl chains (1); 1 (b) halitoxin, built on C 8 -C 11 methyl branched alkyl chains (2); 2 (c) cyclostellettamines, composed of straight C 12 -C 15 alkyl chains (3); 3 and (d) amphitoxin, which is composed of oligomeric chains of 3-alkylpyridinium and 3-alkenylpyridinium units (4a, 4b). 4 Related to these compounds are niphatoxins, non-ring oligomers with uncharged pyridine end groups, 5 and haliclamines, trihydropyridine cyclic compounds. 6 These have been proposed as models of biogenic precursors for many complex alkaloids, such as the manzamines 7 and the petrosins, 8 all isolated from marine sponges.The isolated compounds exerted cytotoxicity towards tumor cell lines and hemolysis, 2 inhibition of the epidermal growth factor and toxicity to fish and mice, 1 inhibition of binding of methyl quinuclidinyl benzilate to muscarinic acetylcholine receptors, 3 and strong antifeeding activity. 4 3-Alkylpyridinium oligomers mimicking the EGF-active factors, with an oxygen atom in place of a methylene group in the alkyl chain, have been recently synthesized. 9 Some of these studies revealed that the higher the polymerization degree the higher were both biological activity 1,9 and hydrophilicity. 9Despite the well-defined structure of a single 3-alkylpyridinium unit, little is known about the size of 3-alkylpyridinium polymers (poly-APS) and their possible formation of supramolecular structures in aqueous solutions that might also have an impact on their biological activities. We found that aqueous extracts from the marine sponge Reniera ()Haliclona) sarai Pulitzer-Finali (Haliclonidae) possess strong anticholinesterase and hemolytic activity as well as ...

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Section: Resultsmentioning

confidence: 99%

Characterization of Anticholinesterase-Active 3-Alkylpyridinium Polymers from the Marine Sponge Reniera sarai in Aqueous Solutions

et al. 1997

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“…[4] However, light scattering techniques are far more powerful because information concerning the sizes and shapes of micelles is obtained, [5,6] as well as more accurate CMC determinations than with other techniques [7] . In the build-up from surfactant monomers to micelles, the transitory existence of intermediate levels of aggregation is to be expected.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Lipopolysaccharide Aggregation by Light Scattering Spectroscopy

et al. 2003

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Lipopolysaccharides (LPS) are cell wall components of Gram-negative bacteria. These molecules behave as bacterial endotoxins and their release into the bloodstream is a determinant of the development of a wide range of pathologies. These amphipathic molecules can self-aggregate into supramolecular structures with different shapes and sizes. The formation of these structures occurs when the LPS concentration is higher than the apparent critical micelle concentration (CMC(a)). Light scattering spectroscopy (both static and dynamic) was used to directly characterize the aggregation process of LPS from Escherichia coli serotype 026:B6. The results point to a CMC(a) value of 14 microg mL(-1) and the existence of premicelle LPS oligomers below this concentration. Both structures were characterized in terms of molecular weight (5.5 x 10(6) and 16 x 10(6) g mol(-1) below and above the CMC(a), respectively), interaction with the aqueous environment, gyration radius (56 and 105 nm), hydrodynamic radius, (60 and 95 nm) and geometry of the supramolecular structures (nearly spherical). Our data indicates that future in vitro experiments should be carried out both below and above the CMC(a). The search for drugs that interact with the aggregates, and thus change the CMC(a) and condition LPS interactions in the bloodstream, could be a new way to prevent certain bacterial-endotoxin-related pathologies.

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“…Under our experimental conditions, CTAB micelles and cells are considered spherical (23), and the ions are distributed in the region r, < r < r, according to the non-linearized Poisson-Boltzmann equation which, for spherical symmetry and if only monovalent ions are present in solution, is expressed as…”

Section: Theoretical Description Of This Electrostatic Approachmentioning

confidence: 99%

An electrostatic approach to negatively charged substrate reactions with hydroxide ion in cationic CTAB micelles

Dolcet¹,

Rodenas²

1990

Can. J. Chem.

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Received August 1, 1 98g2 C. DOLCET and E. RODENAS. Can. J. Chem. 68, 932 (1990).An electrostatic treatment is presented to explain the experimental kinetic data we obtained for the basic hydrolysis of the negatively charged substrates acetylsalicylic acid and 3-acetoxy-2-naphthoic acid. 'This treatment, based on the non-linearized Poisson-Boltzmann equation, considers specific interactions between the counterions and the micellar surface and explains the displacement of these substrates from the micellar to the aqueous phase through bromide counterion addition.Key words: electrostatic approach, cationic CTAB micelles. Introduction In earlier papers we have reported our results in the basic hydrolysis of some aromatic esters in cationic micelles (CTAB, CTACl, CTAOH), hexadecyltrimethilarnmonium bromide, chloride, and hydroxide respectively (1, 2). These results were accounted for with the pseudophase ion-exchange (3,4) and the mass-action models (5). To explain the results for negatively charged substrates like acetylsalicylic acid (2-acetoxybenzoic acid) and 3-acetoxy-2-naphthoic acid the micellar counterion effect had to be taken into account. For reactions in CTAB micelles the addition of an additional Br-counterion to the CTAB micelles displaces these substrates from the micellar to the aqueous phase (6). The opposite effect has been found with positively charged substrates for which Br-counterion addition produces a sharp increase in substrate to micelle binding (7-9). It is also known that the pseudophase ion-exchange model fails at high reactive ion concentrations according to some experimental evidence in literature (10) so that it becomes necessary to consider an increase in the fraction of neutralized micellar head groups (11,12) or to consider an additional reaction pathway in which the reactive ion in the aqueous phase reacts with the micelle bound substrate (13).From all of this evidence, it becomes necessary to develop a new theoretical treatment. For these negatively chargeh substrates, in an early paper, we assumed that the substrate distribution between aqueous and micellar phases was the same as that for ions in solution as did other authors in literature (14). > , This treatment neglects the micellar surface potential and is not able to explain our kinetic results (15).In trying to fit all our kinetic results we developed an electrostatic treatment that treats the ion distribution around micelles by the Poisson-Boltzrnann non-linearized equation (NLPB). The Poisson-Boltzmann ion distribution around micelles has been successfully used to explain the thermodynamic behavior of ionic colloids with monovalent ions (16,17) although it fails to describe the distribution of multi-

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Deduction of micellar shape from angular dissymmetry measurements of light scattered from aqueous sodium dodecyl sulfate solutions at high sodium chloride concentrations

Cited by 192 publications

References 1 publication

Characterization of Anticholinesterase-Active 3-Alkylpyridinium Polymers from the Marine Sponge Reniera sarai in Aqueous Solutions

Characterization of Anticholinesterase-Active 3-Alkylpyridinium Polymers from the Marine Sponge Reniera sarai in Aqueous Solutions

Evaluation of Lipopolysaccharide Aggregation by Light Scattering Spectroscopy

An electrostatic approach to negatively charged substrate reactions with hydroxide ion in cationic CTAB micelles

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