Small-Angle Neutron Scattering and Dynamic Light Scattering from a Polyelectrolyte Solution:  DNA

Nguyen, Huy; Pecora, R.

doi:10.1021/ma970919b

Cited by 120 publications

(177 citation statements)

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“…[10] Circular dichroism and UV absorption measurements were carried out with a Jasco J-715 spectropolarimeter. SAXS analysis was performed in a Kratky compact instrument provided by HECUS MBraun, Graz, Austria.…”

Section: Methodsmentioning

confidence: 99%

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Molecular Recognition Drives Oligonucleotide Binding to Nucleolipid Self‐Assemblies

2007

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Ordered interactions: Selective supramolecular association of oligonucleotides with like‐charged amphiphilic self‐assemblies in aqueous solution, in the absence of divalent cations, is reported. A structural model of the nucleolipoplex, the ordered mesophase formed upon interaction of DNA (red) with anionic nucleolipid assemblies (green), is shown. The hexagonal arrangement is templated by the complementary polynucleotide.

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Section: Methodsmentioning

confidence: 99%

“…[10] An angular scan reveals a diffusive nature [11] for both modes (see the Supporting Information), the corresponding diffusion coefficients of which are reported in Table 1. The DLS data for micellar aggregates (lipid concenScheme 1.…”

mentioning

confidence: 99%

Molecular Recognition Drives Oligonucleotide Binding to Nucleolipid Self‐Assemblies

2007

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“…While there has been a number of DLS reports on the properties of DNA solutions (see, for example Refs. [71][72][73][74]), studies involving interactions between DNA and cationic amphiphiles are in a very limited number [18,24,75].…”

Section: A Dynamic Light Scattering Studymentioning

confidence: 99%

DNA and surfactants in bulk and at interfaces

Dias

Pais

Miguel

et al. 2004

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Recent investigations of the DNA interactions with cationic surfactants and catanionic mixtures are reviewed. Several techniques have been used such as fluorescence microscopy, dynamic light scattering, electron microscopy, and Monte Carlo simulations.The conformational behaviour of large DNA molecules in the presence of cationic surfactant was followed by fluorescence microscopy and also by dynamic light scattering. These techniques were in good agreement and it was possible to observe a discrete transition from extended coils to collapsed globules and their coexistence for intermediate amphiphile concentrations. The dependence on the surfactant alkyl chain was also monitored by fluorescence microscopy and, as expected, lower concentrations of the more hydrophobic surfactant were required to induce DNA compaction, although an excess of positive charges was still required.Monte Carlo simulations on the compaction of a medium size polyanion with shorter polycations were performed. The polyanion chain suffers a sudden collapse as a function of the concentration of condensing agent, and of the number of charges on the polycation molecules. Further increase in the concentration increases the degree of compaction. The compaction was found to be associated with the polycations promoting bridging between different sites of the polyanion. When the total charge of the polycations was lower than that of the polyanion, a significant translational motion of the compacting agent along the polyanion was observed, producing only a small-degree of intrachain segregation, which can explain the excess of positive charges necessary to compact DNA.Dissociation of the DNA-cationic surfactant complexes and a concomitant release of DNA was achieved by addition of anionic surfactants. The unfolding of DNA molecules, previously compacted with cationic surfactant, was shown to be strongly dependent on the anionic surfactant chain length; lower amounts of a longer chain surfactant were needed to release DNA into solution. On the other hand, no dependence on the hydrophobicity of the compacting agent was observed. The structures of the aggregates formed by the two surfactants, after the interaction with DNA, were imaged by cryogenic transmission electron microscopy. It is possible to predict the structure of the aggregates formed by the surfactants, like vesicles, from the phase behaviour of the mixed surfactant systems.Studies on the interactions between DNA and catanionic mixtures were also performed. It was observed that DNA does not interact with negatively charged vesicles, even though they carry positive amphiphiles; however, in the presence of positively charged vesicles, DNA molecules compact and adsorb on their surface.Finally Monte Carlo simulations were performed on the adsorption of a polyelectrolyte on catanionic surfaces. It was observed that the mobile charges in the surface react to the presence of the polyelectrolyte enabling a strong degree of adsorption even though the membrane was globally neutral. Our observati...

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“…Such observations have been reported for different charged macromolecular systems, including synthetic [18][19][20][21][22] and biological polyelectrolyte solutions. [23][24][25] The fast mode is often interpreted as a process involving the diffusion of single polyions. 26 On the other hand, the occurrence and physical meaning of the slow mode is still not well understood, but various studies have shown that such processes or dynamics are related to the presence of aggregates or large domains in polyelectrolytes in the order of 100 nm.…”

Section: Introductionmentioning

confidence: 99%

Dynamic light scattering and viscosimetry of aqueous solutions of pectin, sodium alginate and their mixtures: effects of added salt, concentration, counterions, temperature and chelating agent

Lima¹,

Soldi²

2009

J. Braz. Chem. Soc.

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Efeitos de adição de sal, concentração, presença de contraíons, temperatura e agente quelante em soluções aquosas de pectina, alginato de sódio e misturas destes foram analisadas por viscosimetria e espalhamento de luz dinâmico (DLS). A viscosidade intrínseca dos sistemas binários diminuiu com a adição de sal e com o aumento da temperatura, porém, mostrou-se insensível à adição de NaEDTA. Como esperado, a viscosidade intrínseca do sistema ternário alginato/pectina/água foi igual a média da viscosidade intrínseca determinada para os sistemas binários. Estudos de DLS indicaram a ocorrência de uma distribuição bimodal (presença dos modos de relaxação rápido e lento) para ambos os sistemas binários e ternários a 25 °C, refletindo um processo de agregação. No caso do modo lento de relaxação, um aumento significativo do raio hidrodinâmico foi observado tanto para os sistemas binários como ternário, na presença de NaCl e KCl a 25 °C. No entanto, a 80 °C, o raio hidrodinâmico correspondente ao modo lento em soluções de KCl foi praticamente constante para todos os sistemas estudados e não foi observado para o sistema binário alginato/solução aquosa.The effects of added salt, concentration, counterions, temperature and chelating agent on aqueous solutions of pectin, sodium alginate and their mixtures were analyzed by viscosimetry and dynamic light scattering (DLS) techniques. The intrinsic viscosity of the binary systems decreased with the addition of salt and with temperature, while it was found to be insensitive to the addition of NaEDTA. As expected the intrinsic viscosity of the ternary alginate/pectin/water system was equal to the average of the intrinsic viscosity for the binary systems. The DLS studies indicated a bimodal distribution (fast and slow relaxation modes) for both binary and ternary systems at 25 °C, reflecting aggregation. A significant increase in the hydrodynamic radius, in the case of the slow mode, was observed for the binary and ternary systems in the presence of NaCl and KCl at 25 °C. However, at 80 °C the hydrodynamic radius for the slow mode in KCl solutions was practically constant for all the studied systems, except for the alginate binary solutions in which were not observed.

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Small-Angle Neutron Scattering and Dynamic Light Scattering from a Polyelectrolyte Solution: DNA

Cited by 120 publications

References 50 publications

Molecular Recognition Drives Oligonucleotide Binding to Nucleolipid Self‐Assemblies

Molecular Recognition Drives Oligonucleotide Binding to Nucleolipid Self‐Assemblies

DNA and surfactants in bulk and at interfaces

Dynamic light scattering and viscosimetry of aqueous solutions of pectin, sodium alginate and their mixtures: effects of added salt, concentration, counterions, temperature and chelating agent

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