A Field Dependent <sup>2</sup>H Nuclear Magnetic Relaxation Study of the Aggregation Behavior in Micellar Solutions of CTAB and SDS

Törnblom, Maria; Henriksson, Ulf; Ginley, Molly

doi:10.1021/jp9708660

Cited by 9 publications

(7 citation statements)

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“…Since the surfactants aggregate into micelles at concentrations above the CMC and the transport of the surfactants from the bulk to the subsurface is a convectiondominated process, rather than the molecular weight of free surfactant monomers, it is the size, shape, aggregation number, and even relaxation time (stability) of the micelles that dominate the transport process. CTAB's higher dynamic interfacial tension may be due to the fact that the size of the CTAB micelle is larger than that of SDS, 37 which results in slower transport of micelles to the subsurface and ultimately a lower concentration of monomers in the subsurface.…”

Section: The Dynamic Interfacial Tension With Varied Dropletmentioning

confidence: 99%

The Dynamic Effects of Surfactants on Droplet Formation in Coaxial Microfluidic Devices

Dong

Zhao

et al. 2012

Langmuir

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Droplet emulsification in microfluidic devices involves the constant formation of fresh interfaces between two immiscible fluids. When the multiphase system contains surfactant, dynamic mass transfer of the surfactant onto the interface results in a dynamic interfacial tension different from the static interfacial tension measured in an equilibrium state. In this work, we have systematically investigated the effects of surfactant concentration and type on the dynamic interfacial tension of two different liquid-liquid two phase systems [N-hexane/water-sodium dodecyl sulfate (SDS) and N-hexane/water-cetyltrimethylammonium bromide (CTAB)] rapidly producing relatively small droplets in coaxial microfluidic devices. Dynamic interfacial tension experiments using the pendent drop method and a tensiometer were conducted, and a semiempirical equation was developed to put into context the effects of surfactants and the experimental conditions on droplet formation and dynamic interfacial tension in dynamic microchannel flows. The results presented in this work provide a more in-depth understanding of the dynamic effects of surfactants on droplet formation and the precise controllable preparation of monodispersed droplets in microfluidic devices.

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Section: The Dynamic Interfacial Tension With Varied Dropletmentioning

confidence: 99%

The Dynamic Effects of Surfactants on Droplet Formation in Coaxial Microfluidic Devices

Dong

Zhao

et al. 2012

Langmuir

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“…Therefore, an easy and reliable experimental determination of micellar aggregation number is of particular interest. A number of physical methods have been used for the determination of micelle aggregation number such as NMR spectroscopy [6,7], static light scattering (references in the text below), small-angle neutron scattering [8][9][10], small-angle X-ray scattering [11], fluorescence probing methods, and electron paramagnetic resonance [8,[12][13][14][15][16]. Some of them are limited to the aggregation number determination at the surfactant concentration equal to CMC which only provides aggregation number values for isolated non-interacting particles.…”

Section: Introductionmentioning

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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“…12,24 In the dynamical context, 2 H serves as a more accurate relaxation probe relative to 13 C in extracting slow dynamics occurring in the nanoseconds' time scale. 39 This stems from an exclusive intramolecular relaxation interaction and a large dynamic range offered by the quadrupolar interaction of 2 H for the motional modulation. 39 Variable magnetic field 2 H spin-relaxation data (R 2 and R 1 ) for site-specific deuterium labeled (at α position) surfactant micelles when subjected to the two-step model 35,37−40 facilitates to extract of similar information as that of 13 C in a more accurate way.…”

Section: ■ Introductionmentioning

confidence: 99%

“…39 This stems from an exclusive intramolecular relaxation interaction and a large dynamic range offered by the quadrupolar interaction of 2 H for the motional modulation. 39 Variable magnetic field 2 H spin-relaxation data (R 2 and R 1 ) for site-specific deuterium labeled (at α position) surfactant micelles when subjected to the two-step model 35,37−40 facilitates to extract of similar information as that of 13 C in a more accurate way. However, if one is interested in the geometrical aspects of micelles (size and shape) in the presence of additives such as solvents, drugs, polymers, etc., as well as the function of salinity, concentration, and temperature, it is often sufficient to monitor relaxation changes (ΔR = R 2 − R 1 ) at a single magnetic field.…”

Section: ■ Introductionmentioning

confidence: 99%

NMR Studies on the Interaction of Anticancer Drug Doxorubicin with Membrane Mimetic SDS

2022

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In the formulation of efficient drug delivery systems, it is essential to unravel the structural and dynamical aspects of the drug’s interaction with biological membranes. This has been done for the anticancer drug–membrane system comprising doxorubicin hydrochloride (DOX), a water-soluble anticancer drug, and the micellar sodium dodecyl sulfate (SDS), the latter serving as a useful mimic for membrane proteins. Using a multimodal NMR approach involving 1H, 2H, and 13C as probe nuclei and through the determination of chemical shifts, spin-relaxation, nuclear Overhauser enhancements (NOE), and translational self-diffusion (SD), the binding characteristics of the DOX with SDS have been determined. The perturbation to 13C chemical shifts of SDS indicate the penetration of DOX into the SDS micelle, which is further revealed by 1H–1H NOESY and SD measurements. 2H spin-relaxation measurements and their analysis using a two-step model show DOX induced SDS micellar volume changes, which determine the correlation times involved in the DOX–SDS mobility.

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A Field Dependent ²H Nuclear Magnetic Relaxation Study of the Aggregation Behavior in Micellar Solutions of CTAB and SDS

Cited by 9 publications

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The Dynamic Effects of Surfactants on Droplet Formation in Coaxial Microfluidic Devices

The Dynamic Effects of Surfactants on Droplet Formation in Coaxial Microfluidic Devices

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

NMR Studies on the Interaction of Anticancer Drug Doxorubicin with Membrane Mimetic SDS

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A Field Dependent 2H Nuclear Magnetic Relaxation Study of the Aggregation Behavior in Micellar Solutions of CTAB and SDS

Cited by 9 publications

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The Dynamic Effects of Surfactants on Droplet Formation in Coaxial Microfluidic Devices

The Dynamic Effects of Surfactants on Droplet Formation in Coaxial Microfluidic Devices

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

NMR Studies on the Interaction of Anticancer Drug Doxorubicin with Membrane Mimetic SDS

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A Field Dependent ²H Nuclear Magnetic Relaxation Study of the Aggregation Behavior in Micellar Solutions of CTAB and SDS