Ionic Surfactant Aggregates in Saline Solutions: Sodium Dodecyl Sulfate (SDS) in the Presence of Excess Sodium Chloride (NaCl) or Calcium Chloride (CaCl<sub>2</sub>)

Sammalkorpi, Maria; Karttunen, Mikko; Haataja, Mikko

doi:10.1021/jp901228v

Cited by 212 publications

(187 citation statements)

References 95 publications

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“…This results from the chain symmetry, and has been previously reported for, e.g., SDS in bulk and at interfaces. 27,68 Furthermore, the lipid head group interactions influence the lipid packing on the substrate. Simulations of HD isolate this effect as they represent just the tail interactions with the substrate.…”

Section: Resultsmentioning

confidence: 99%

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

2015

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Control of aqueous dispersion is central in the processing and usage of nanoscale hydrophobic objects. However, selecting dispersive agents based on the size and form of the hydrophobic object and the role of coating morphology in dispersion efficiency remain important open questions. Here, the effect of the substrate and the dispersing molecule curvature, as well as, the influence of dispersant concentration on the adsorption morphology are examined by molecular simulations of graphene and carbon nanotube (CNT) substrates with phospholipids of varying curvature as the dispersing agents. Lipid spontaneous curvature is increased from close to zero (effectively cylindrical lipid) to highly positive (effectively conical lipid) by studying double tailed dipalmitoylphosphadidylcholine (DPPC) and single tailed lysophosphadidylcholine (LPC) which differ in the number of acyl chains but have identical head group.We find that lipids are good dispersion agents for both planar and curved nanoparticles and induce a dispersive barrier non-size selectively. Differences in dispersion efficiency arise from lipid head group density and their extension from the hydrophobic substrate in the adsorption morphology. We map the packing morphology contributing factors and report that the aggregate morphologies depend on the competition of interactions rising from 1) hydrophobicity driven maximization of lipid-substrate contacts and lipid self-adhesion, 2) tail bending energy cost, 3) preferential alignment along the graphitic substrate principal axes, and 4) lipid head group preferential packing.Curved substrates adjust the morphology by changing the balance between the interaction strengths. Jointly, the findings show substrate curvature and dimensions are a way to tune lipid adsorption to desired, self-assembling patterns. Besides engineering dispersion efficiency, the findings could bear significance in designing materials with defined molecular scale, molecular coatings for orientation specific CNT assembly or lipid-based molecular masks and patterning on graphene.2

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Section: Resultsmentioning

confidence: 99%

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

2015

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“…65 One of the exciting topics in electrolyte solutions concerns the distribution of ions around other charged objects. 66 In the present case with counterions, the proper theoretical context is given by the (mean-field) Debye−Huckel (DH) theory, where for counterions around a charged particle, one combines the Poisson equation to specify the electrostatic potential of an ion with the Boltzmann equation for charge distribution. In radial symmetry, the Debye−Huckel description for the counterion distribution around a charged NP reads as Ae −Br /r + C, where A, B, and C are (positive) constants.…”

Section: ■ Resultsmentioning

confidence: 99%

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

et al. 2012

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Charged monolayer-protected gold nanoparticles (AuNPs) have been studied in aqueous solution by performing atomistic molecular dynamics simulations at physiological temperature (310 K). Particular attention has been paid to electrostatic properties that modulate the formation of a complex comprised of the nanoparticle together with surrounding ions and water. We focus on Au 144 nanoparticles that comprise a nearly spherical Au core (diameter ∼2 nm), a passivating Au−S interface, and functionalized alkanethiol chains. Cationic and anionic AuNPs have been modeled with amine and carboxyl terminal groups and Cl − /Na + counterions, respectively. The radial distribution functions show that the side chains and terminal groups show significant flexibility. The orientation of water is distinct in the first solvation shell, and AuNPs cause a long-range effect in the solvent structure. The radial electrostatic potential displays a minimum for AuNP − at 1.9 nm from the center of the nanoparticle, marking a preferable location for Na + , while the AuNP + potential (affecting the distribution of Cl − ) rises almost monotonically with a local maximum. Comparison to Debye−Huckel theory shows very good agreement for radial ion distribution, as expected, with a Debye screening length of about 0.2−0.3 nm. Considerations of zeta potential predict that both anionic and cationic AuNPs avoid coagulation. The results highlight the importance of long-range electrostatic interactions in determining nanoparticle properties in aqueous solutions. They suggest that electrostatics is one of the central factors in complexation of AuNPs with other nanomaterials and biological systems, and that effects of electrostatics as water-mediated interactions are relatively long-ranged, which likely plays a role in, e.g., the interplay between nanoparticles and lipid membranes that surround cells. ■ INTRODUCTIONNanoparticles (NPs, size range 1−100 nm) have many interesting properties, as they bridge the gap between bulk materials and atomic or molecular structures.1,2 Typically, the physical properties of bulk materials do not depend on the size of the sample, while at the nanoscale size-dependent properties are frequently encountered. Two contributing factors for the size dependence are (a) number of surface atoms whose percentage reduces as the NP size increases toward the bulk limit and (b) quantum confinement effects at the smallest length scales (<10 nm) where the electronic structure plays a significant role in determining the composition, stability, structure, and function of NPs. 3,4 Nanoparticles often display fascinating optical properties because of quantum effects, and, e.g., gold nanoparticles (AuNPs) appear from yellow to deep red and black in solution depending on their size. 5 In photovoltaic cells, absorption of solar radiation is much higher for semiconductor materials comprised of NPs than for continuous sheets of thin films (e.g., CdTe, ZnO).6 For phase-change materials used in optical data storage and nonvolatile computer ...

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“…Therefore, the micellar growth of SDS micelles with the increasing SDS concentration cannot be related only to the geometry of molecule but may indicate a significant role of intermolecular interactions in the explanation of different aggregation behaviour of DTAB vs. SDS surfactant molecules. In molecular dynamics simulation studies of SDS micelles [43][44][45][46][47][48][49][50], interactions through hydrogen bonds and electrolyte ions were found as one of the main factors determining the micellar structure. As follows from the charge distribution in the polar parts of DTAB and SDS molecules which are shown in Fig.…”

Section: Analysis Of Intramicellar Interactionsmentioning

confidence: 99%

Determination of micelle aggregation numbers of alkyltrimethylammonium bromide and sodium dodecyl sulfate surfactants using time-resolved fluorescence quenching

2015

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Abstract:The time-resolved fluorescence quenching method was applied to determine the micelle aggregation number of cationic single-chain surfactants dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS). The concentration dependence of micelle aggregation number was found to be linear for all investigated surfactants in the concentration range 2-15 × the value of critical micelle concentration of the respective surfactant. The values of micelle aggregation number were found in the range 30-77. Different trends in the linear concentration dependence of micelle aggregation number were observed for cationic surfactants and for the anionic surfactant SDS. A small slope value was found for cationic surfactants, while the SDS micelle aggregation number concentration dependence showed significantly a larger slope value. The aggregation number increase with the increasing SDS concentration results in the micellar growth. Results from a simple analysis based on computer models of cationic and anionic surfactant molecules with dodecyl chains supports, the formation of intramicellar hydrogen bonding between surfactant molecules in SDS micelle shell.

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Ionic Surfactant Aggregates in Saline Solutions: Sodium Dodecyl Sulfate (SDS) in the Presence of Excess Sodium Chloride (NaCl) or Calcium Chloride (CaCl₂)

Cited by 212 publications

References 95 publications

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

Determination of micelle aggregation numbers of alkyltrimethylammonium bromide and sodium dodecyl sulfate surfactants using time-resolved fluorescence quenching

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Ionic Surfactant Aggregates in Saline Solutions: Sodium Dodecyl Sulfate (SDS) in the Presence of Excess Sodium Chloride (NaCl) or Calcium Chloride (CaCl2)

Cited by 212 publications

References 95 publications

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

Atomistic Simulations of Functional Au144(SR)60 Gold Nanoparticles in Aqueous Environment

Determination of micelle aggregation numbers of alkyltrimethylammonium bromide and sodium dodecyl sulfate surfactants using time-resolved fluorescence quenching

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Product

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Ionic Surfactant Aggregates in Saline Solutions: Sodium Dodecyl Sulfate (SDS) in the Presence of Excess Sodium Chloride (NaCl) or Calcium Chloride (CaCl₂)

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment