Effect of Headgroup on DNA−Cationic Surfactant Interactions

Dasgupta, Antara; Das, Prasanta Kumar; Dias, Rita S.; Miguel, Maria G.; Lindman, Björn; Jadhav, Vaibhav; Gnanamani, Muthaiah; Maiti, Souvik

doi:10.1021/jp068571m

Cited by 81 publications

(78 citation statements)

References 54 publications

(117 reference statements)

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“…25,36 The invariance of the cac with changes in the headgroup contrasts two other observations: first, the cmc's of the surfactants are quite different, and, second, the accessibility of DNA to ethidium bromide binding is considerably higher for the more hydrophilic surfactants, as shown in a previous publication. 27 However, both observations can easily be rationalized from our understanding of surfactant self-assembly. It is well-known that by adding a (even weak) nonionic amphiphile, such as an alcohol, ionic surfactant micelles are stabilized by an electrostatic screening effect, and thus the cmc is lowered; 33 the lower cmc of the hydroxylated surfactants is ascribed to an analogous effect.…”

Section: Resultsmentioning

confidence: 99%

“…However, now another difference between the headgroups becomes accentuated, i.e., that of mere physical size; hydroxylation increases the headgroup volume considerably. It is well-established that surfactant packing determines the type of aggregate formed; basically, the larger the headgroup, the smaller the aggregates, 27 leading to small spherical micelles for surfactants with large headgroups, while larger aggregates are obtained with small headgroups. For the surfactants studied alone, differences are small since the effective headgroup size is strongly determined by the electrostatic repulsions.…”

Section: Resultsmentioning

confidence: 99%

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Interaction between DNA and Cationic Surfactants: Effect of DNA Conformation and Surfactant Headgroup

et al. 2008

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The interactions between DNA and a number of different cationic surfactants, differing in headgroup polarity, were investigated by electric conductivity measurements and fluorescence microscopy. It was observed that, the critical association concentration (cac), characterizing the onset of surfactant binding to DNA, does not vary significantly with the architecture of the headgroup. However, comparing with the critical micelle concentration (cmc) in the absence of DNA, it can be inferred that the micelles of a surfactant with a simple quaternary ammonium headgroup are much more stabilized by the presence of DNA than those of surfactants with hydroxylated headgroups. In line with previous studies of polymer-surfactant association, the cac does not vary significantly with either the DNA concentration or its chain length. On the other hand, a novel observation is that the cac is much lower when DNA is denaturated and in the single-stranded conformation, than for the double-helix DNA. This is contrary to expectation for a simple electrostatically driven association. Thus previous studies of polyelectrolytesurfactant systems have shown that the cac decreases strongly with increasing linear charge density of the polyion. Since double-stranded DNA (dsDNA) has twice as large linear charge density as single-stranded DNA (ssDNA), the stronger binding in the latter case indicates an important role of nonelectrostatic effects. Both a higher flexibility of ssDNA and a higher hydrophobicity due to the exposed bases are found to play a role, with the hydrophobic interaction argued to be more important. The significance of hydrophobic DNA-surfactant interaction is in line with other observations. The significance of nonelectrostatic effects is also indicated in significant differences in cac between different surfactants for ssDNA but not for dsDNA. For lower concentrations of DNA, the conductivity measurements presented an "anomalous" feature, i.e., a second inflection point for surfactant concentrations below the cac; this feature was not displayed at higher concentrations of DNA. The effect is attributed to the presence of a mixture of ss-and dsDNA molecules. Thus the stability of dsDNA is dependent on a certain ion atmosphere; at lower ion concentrations the electrostatic repulsions between the DNA strands become too strong compared to the attractive interactions, and there is a dissociation into the individual strands. Fluorescence microscopy studies, performed at much lower DNA concentrations, demonstrated a transformation of dsDNA from an extended "coil" state to a compact "globule" condition, with a broad concentration region of coexistence of coils and globules. The onset of DNA compaction coincides roughly with the cac values obtained from conductivity measurements. This is in line with the observed independence of cac on the DNA concentration, together with the assumption that the onset of binding corresponds to an initiation of DNA compaction. No major changes in either the onset of compaction or complete compaction...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Interaction between DNA and Cationic Surfactants: Effect of DNA Conformation and Surfactant Headgroup

et al. 2008

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“…In a previous study we have found that the cytotoxicity decreases substantially with increasing the number of hydroxyl substitutions (increasing the hydrophilicity) on the surfactant head group. 11 It is thus possible that the presence of bulky groups on the surfactant head group plays an important role in shielding the amino groups, thus reducing their interaction with the cell surface. However, without a solid mechanistic understanding of toxicity such deductions, although of possible practical significance remain speculations.…”

Section: Resultsmentioning

confidence: 99%

Effect of the Head-Group Geometry of Amino Acid-Based Cationic Surfactants on Interaction with Plasmid DNA

Jadhav¹,

Maiti²,

Dasgupta³

et al. 2008

Biomacromolecules

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The interaction between DNA and different types of amino acid-based cationic surfactants was investigated. Particular attention was directed to determine the extent of influence of surfactant head-group geometry toward tuning the interaction behavior of these surfactants with DNA. An overview is obtained by gel retardation assay, isothermal titration calorimetry, fluorescence spectroscopy, and circular dichroism at different mole ratios of surfactant/DNA; also, cell viability was assessed. The studies show that the surfactants with more complex/ bulkier hydrophobic head group interact more strongly with DNA but exclude ethidium bromide less efficiently; thus, the accessibility of DNA to small molecules is preserved to a certain extent. The presence of more hydrophobic groups surrounding the positive amino charge also gave rise to a significantly lower cytotoxicity. The surfactant self-assembly pattern is quite different without and with DNA, illustrating the roles of electrostatic and steric effects in determining the effective shape of a surfactant molecule.

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“…17 The surfactants used there were to some extent common with that used here. But the observations on their interaction with gelatin do not fully comply with DNA.…”

Section: Influence Of Surfactant Head Group On Gelatin-surfactant Commentioning

confidence: 99%

“…Physicochemical and interactional properties of this kind have been scarcely explored in the past. 17,18 The study has been performed at pHs 5⋅4 and 9⋅0 without and with gelatin. With reference to the reported gelatin-CTAB interaction profile, 49 we have illustrated in detail and discussed the effects of the surfactant head group modification and pH on the said interaction process.…”

Section: Introductionmentioning

confidence: 99%

Physicochemistry of hexadecylammonium bromide and its methyl and ethanolic head group analogues in buffered aqueous and gelatin solution

Mitra

Moulik

2010

J Chem Sci

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In this work, the interfacial and bulk behaviour of the amphiphiles hexadecylammonium bromide and its methyl and ethanolic head group analogues in buffered aqueous and gelatin solution has been examined. The analogues are of two categories: the methyl and the combined methyl and ethanolic head group representatives are considered as Group A compounds, and all non-methyl but ethanolic head group species are taken as Group B compounds. Different physical techniques have been employed to ascertain the amphiphilic behaviour in solution. The self-aggregation of these surfactants at different pH has been studied along with pH dependent interfacial activity of gelatin. The interaction of the two categories of the surfactants with gelatin at different pH has been investigated. A scheme for this interaction at various stages of the process has been proposed. The influence of the surfactant head groups on the interaction process has been assessed.

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Effect of Headgroup on DNA−Cationic Surfactant Interactions

Cited by 81 publications

References 54 publications

Interaction between DNA and Cationic Surfactants: Effect of DNA Conformation and Surfactant Headgroup

Interaction between DNA and Cationic Surfactants: Effect of DNA Conformation and Surfactant Headgroup

Effect of the Head-Group Geometry of Amino Acid-Based Cationic Surfactants on Interaction with Plasmid DNA

Physicochemistry of hexadecylammonium bromide and its methyl and ethanolic head group analogues in buffered aqueous and gelatin solution

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