NMR Studies of Restricted Diffusion in Lyotropic Systems

Szutkowski, Kosma; Klinowski, Jacek; Jurga, Stefan

doi:10.1006/snmr.2002.0087

Cited by 9 publications

(11 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, for the experimental FE data at Δ = 50 ms, 1/ α can be estimated as 0.11. These tortuosity values are similar to those reported previously for PGSE experiments on lyotropic lamellar and hexagonal systems . The tortuosity values, α, estimated from the diffusion simulations were therefore ~3 times lower than those from the experimental data.…”

Section: Discussionsupporting

confidence: 88%

Na⁺ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling

Larkin

Garvey

Shishmarev

et al. 2016

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

The apparent diffusion coefficients of Na ions and the solute 2-fluoroethylamine present in the aqueous domain of a Myverol/water bulk bicontinuous cubic phase (BCP) were measured using pulsed field-gradient spin echo (PGSE) NMR spectroscopy. The measured values were dependent on the diffusion time interval, which is a characteristic of restricted diffusion. The translational motion of Na and water in the aqueous channels of a cubic phase were simulated using a Monte-Carlo random walk algorithm, and the simulation results were compared with those from real PGSE NMR experiments. The simulations indicated that diffusion of Na ions and water would appear to be restricted even on the shortest timescales available to PGSE NMR experiments. The micro-viscosity of the aqueous domain of the BCPs was estimated from the longitudinal relaxation times of Na and 2-fluoroethylamine; this was three times higher than in free solution and suggests one of (but not the only) likely impediments to the release of hydrophilic drugs from stabilised aqueous dispersions of BCPs (cubosomes) when they are used therapeutically in vivo. Monte Carlo simulations of diffusive efflux from cubosomes suggest that the principal impediment to drug release is presented by a surfactant or lipid barrier at the cubosome surface, which separates the BCP aqueous channels from the bulk solution. The dynamics inferred from these studies informs quantitative predictions of drug delivery from cubosomes. Copyright © 2016 John Wiley & Sons, Ltd.

show abstract

Section: Discussionsupporting

confidence: 88%

Na⁺ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling

Larkin

Garvey

Shishmarev

et al. 2016

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

show abstract

“…3S, Supplementary Material). This results from free bulk diffusion (unrestricted system) with the diffusion coefficient independent of the diffusion time [45,46].…”

Section: Self-diffusion Measurementsmentioning

confidence: 99%

Thermodynamics, size, and dynamics of zwitterionic dodecylphosphocholine and anionic sodium dodecyl sulfate mixed micelles

Sikorska

Wyrzykowski

Szutkowski

et al. 2015

J Therm Anal Calorim

Self Cite

View full text Add to dashboard Cite

The thermodynamic properties of micellization for dodecylphosphocholine (DPC), sodium dodecyl sulfate (SDS), and their mixtures were studied using isothermal titration calorimetry. NMR relaxation measurements were used to explore molecular mobility of the DPC-containing micelles, whereas the diffusion measurements were taken to determine the micelle size. The DPC/SDS mixed systems reveal a tendency to form two kinds of micelles in buffered solution at lower temperatures. An increase in temperature as well as the transfer of the DPC/SDS mixed micelles from buffered to unbuffered solution results in only a single-step micellization process. The average size of the DPC-containing micelles is only slightly dependent on the SDS fraction. Examination of the data of spin-spin relaxation (T 2 ) shows that methylene protons on the polar headgroup of DPC and methylene protons (H1) on the hydrocarbon chain in the micellar systems studied reveal a heterogeneous dynamic behavior reflected in a twocomponent T 2 relaxation in the whole temperature range. The latter is the main constituent of the rigid interfacial layer core protecting the penetration of water into the hydrophobic interior.

show abstract

“…66 The short-time dependence of the apparent diffusion coefficient is well described by Mitra model for restricted diffusion. 66,67 While the short-time dependence is controlled by surface-to-volume ratio S/V, the long-time diffusion limit is related to the system tortuosity 1/D eff , where D eff is the effective diffusion coefficient. An overall dependence of the D app (Δ) is described by Pade approximant.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

Dispersion of Water Proton Spin–Lattice Relaxation Rates in Aqueous Solutions of Multiwall Carbon Nanotubes (MWCNTs) Stabilized via Alkyloxymethylimidazolium Surfactants

et al. 2017

Self Cite

View full text Add to dashboard Cite

Carbon nanotubes and a number of other carbon nanomaterials have a tendency to aggregate, which often resulted in difficulties of dispersion of these nanomaterials in aqueous solutions. The ability of dicationic (gemini) surfactants to disperse multiwall carbon nanotubes in water and the dynamic processes taking place at the water–multiwall carbon nanotubes (MWCTs) interface are studied. Stable dispersions of multiwall carbon nanotubes with selected gemini surfactants (1,1′-(1,6-hexanediyl)bis(3-alkyloxymethylimidazolium) dichlorides) were prepared and characterized by nuclear magnetic relaxation dispersion (NMRD), NMR diffusometry, scanning and transmission electron microscopy, and Fourier transform infrared spectroscopy. The addition of multiwall carbon nanotubes to aqueous solutions of studied gemini surfactants leads to significant paramagnetic enhancement of the spin–lattice relaxation processes, which gets more pronounced with increasing concentration of well-dispersed MWNTs in water. The dominant role of outer sphere (OS) relaxation mechanism in total observed R 1, governed by two-dimensional diffusion of water on the carbon nanotube surface in the vicinity of paramagnetic centers incorporated in the MWCNTs’ sidewalls (mainly of iron origin), was assumed to explain NMRD data. The NMR diffusion experiments confirm the existence of restricted water diffusion in the studied supernatants. The NMR diffusion results are consistent with the FTIR and NMR proton spin–lattice relaxation dispersion in which the more effective R 1 dispersion noticed for the sample with IMIC6C12 was ascribed to the better accessibility of water molecules to the surface of the MWCNTs.

show abstract

NMR Studies of Restricted Diffusion in Lyotropic Systems

Cited by 9 publications

References 13 publications

Na⁺ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling

Na⁺ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling

Thermodynamics, size, and dynamics of zwitterionic dodecylphosphocholine and anionic sodium dodecyl sulfate mixed micelles

Dispersion of Water Proton Spin–Lattice Relaxation Rates in Aqueous Solutions of Multiwall Carbon Nanotubes (MWCNTs) Stabilized via Alkyloxymethylimidazolium Surfactants

Contact Info

Product

Resources

About

NMR Studies of Restricted Diffusion in Lyotropic Systems

Cited by 9 publications

References 13 publications

Na+ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling

Na+ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling

Thermodynamics, size, and dynamics of zwitterionic dodecylphosphocholine and anionic sodium dodecyl sulfate mixed micelles

Dispersion of Water Proton Spin–Lattice Relaxation Rates in Aqueous Solutions of Multiwall Carbon Nanotubes (MWCNTs) Stabilized via Alkyloxymethylimidazolium Surfactants

Contact Info

Product

Resources

About

Na⁺ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling

Na⁺ and solute diffusion in aqueous channels of Myverol bicontinuous cubic phase: PGSE NMR and computer modelling