Enhanced Emulsifying Ability of Deoxycholate through Dynamic Interaction with Layered Double Hydroxide
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The emulsifying ability of the naturally occurring surfactant deoxycholic acid (DCA) was improved by dynamic interaction with nanometric layered particles, layered double hydroxide (LDH). As DCA molecules are rigid due to the facial configuration of hydrophobic-hydrophilic groups, they tend to form molecular aggregation in an acidic condition or imbalanced water-lipid ratios. In this study, the homogeneous hybrids of DCA and LDH were obtained by the in situ growth of LDH at a DCA molecule. The DCA-LDH hybrid successfully prevented the molecular aggregation of DCA at an acidic pH and imbalanced water-to-oil ratio. The dynamic light scattering showed that the hydrodynamic radius of micelle in the emulsion made with DCA-LDH maintained its small size (<500 nm), while upon pH change and dilution with water, that made with DCA only uncontrollably increased up to ~3000 nm. The polydispersity index value of the DCA-LDH emulsion remained constant (<0.3) after the pH change and dilution with water, indicating the high stability of the formulation. Furthermore, time-dependent turbidity monitoring revealed that the DCA-only formulation suffered from serious coalescence and creaming compared with the DCA-LDH formulation. It is suggested that the dynamic interaction between LDH layers and DCA prevented molecular aggregation under unfavorable conditions for the oil-in-water emulsion.Keywords:
Dispersity
Hydrodynamic radius
Dilution
Hydrophobic effect
Size polydispersity is a common phenomenon that strongly influences the physicochemical properties of nanoparticles (NPs). We present an analytical approach that is universally applicable to characterizing optically anisotropic round NPs and determines directly the number-averaged size distribution and polydispersity via depolarized dynamic light scattering (DDLS). To demonstrate, we use aqueous suspensions of Au NPs of different sizes and surface functionalization.
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Surface Modification
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Hydrodynamic radius
Polystyrene
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Three kinds of polyglycerol fatty acid esters were used as emulsifiers to produce curcumin-loaded nanoemulsions by low-energy emulsification. Characterization of nanoemulsions was performed by measuring the droplet size, polydispersity index, and zeta potential. The morphology of the curcumin-loaded nanoemulsions was observed by transmission electron microscopy. The mean droplet size ranged from 19.6 ± 0.3 nm to 76.2 ± 2.3 nm, and the polydispersity index was less than 0.15 in all conditions. Physical stability was observed by multiple light scattering and dynamic light scattering methods, and polyglycerol fatty acid ester-based nanoemulsions were found to be remarkably stable for 60 days. After 60 days, 78.9–86.1% of the initial total amount of curcumin was still preserved in the nanoemulsions, which is a promising result when compared with those of other nano-encapsulation systems.
Dispersity
Zeta potential
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The synthesis of nanoparticles of the porous flexible iron fumarate MIL-88A (MIL stands for Materials from Institut Lavoisier) has been studied through the use of several synthetic routes using non-toxic solvents. Hydro-solvothermal synthesis under dynamic or static, ambient or autogenous pressure conditions, assisted or not by microwave irradiation or ultrasonic methods have been compared in terms of particle size, polydispersity and yield. Different parameters such as temperature, time, concentration, pH or the use of additives (base, inhibitor) were evaluated. The resulting nanoparticles were characterised using X-ray powder diffraction (XRPD), dynamic light scattering (DLS), transmission and scanning electron microscopy (TEM and SEM) and the yield of the reaction was estimated. Although significant amounts of small nanoparticles (∼200 nm) were obtained from each synthetic route, most conditions led to an important polydispersity. Ultrasonic synthesis led, on the contrary, to very low yields of small and monodisperse nanoparticles. Finally, only microwave assisted hydrothermal synthesis afforded the successful fast synthesis of high yields of small (<100 nm) and monodispersed nanoparticles.
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Hydrothermal Synthesis
Powder Diffraction
Particle (ecology)
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Dispersity
Thermal Stability
Static light scattering
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We have introduced both electrophoretic and dynamic light scattering to evaluate the polydispersity, nanodispersity, and stability of single-walled carbon nanotubes (SWNTs) in distilled water with surfactants. By controlling the sodium dodecyl sulfate composition and some pretreatment by sonication, we were able to achieve nanodispersion (dispersion into individual nanotubes). The polydispersity was well described by combining both methods. We further showed that the nanodispersion and length distribution observed in the dynamic light scattering spectra were clearly identified by atomic force microscopy. Although surfactants with aliphatic groups can nanodisperse SWNT bundles, the dispersivity and stability depended seriously on the sample preparation process. Our measurements showed that a combination of electrophoretic and dynamic light scattering can provide a convenient and robust means of measuring polydispersity, nanodispersity, and stability of SWNTs in various solutions.
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Sonication
Dispersion stability
Distilled water
Sodium dodecyl sulfate
Electrophoretic light scattering
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Dispersity
Triton X-100
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Microemulsion
Hydrodynamic radius
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Water-in-oil microemulsion droplets (MEDs) are thermodynamically stable supramolecular structures formed in a mixture of water and oil, stabilized by surfactant layer. Here we use fluorescence correlation spectroscopy (FCS) to measure the diffusion, and the size, size distribution, and polydispersity of MEDs prepared in ternary mixtures of water/oil/sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in heptane, isooctane, and nonane at (near) single droplet level. We compare FCS data directly to dynamic light scattering (DLS) data, which shows that the optical matching point (OMP) conditions of MEDs in different oils (where excess optical polarizability of droplets vanish) severely influence DLS data, while FCS extracts the accurate size, size distribution, and polydispersity of AOT-MEDs in all three oils. This suggests that extreme precaution must be taken in acquiring and explaining DLS data of MEDs in solution. FCS data show nearly identical W0-dependent (peak) size variations of AOT-MEDs in all three oils, though a subtle increase in (average) polydispersity of droplets is observed with increase in carbon chain length of oils. Establishing the accuracy of FCS data for AOT-MEDs, we further apply FCS to measure the size parameters of MEDs prepared in a quaternary mixture of water/oil/cetyltrimethylammonium bromide (CTAB)/1-butanol in hexane, heptane, and isooctane. Unlike AOT-MEDs, FCS data show substantial effect of added cosurfactant (1-butanol) and external oil on size, size distribution and polydispersity of quaternary CTAB-MEDs. Analysis of size distributions reveals large variation of polydispersity which possibly indicates the existence of larger shape heterogeneity, together with size heterogeneity, of CTAB-MEDs compared to AOT-MEDs in solution.
Dispersity
Microemulsion
Heptane
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This study aims to rationalize the variability in the measured size of nanomaterials (NMs) by some of the most commonly applied techniques in the field of nano(eco)toxicology and environmental sciences, including atomic force microscopy (AFM), dynamic light scattering (DLS), and flow field-flow fractionation (FlFFF). A validated sample preparation procedure for size evaluation by AFM is presented, along with a quantitative explanation of the variability of measured sizes by FlFFF, AFM, and DLS. The ratio of the z-average hydrodynamic diameter (dDLS) by DLS and the particle height by AFM (dAFM) approaches 1.0 for monodisperse samples and increases with sample polydispersity. A polydispersity index of 0.1 is suggested as a suitable limit above which DLS data can no longer be interpreted accurately. Conversion of the volume particle size distribution (PSD) by FlFFF–UV to the number PSD reduces the differences observed between the sizes measured by FlFFF (dFlFFF) and AFM. The remaining differences in the measured sizes can be attributed to particle structure (sphericity and permeability). The ratio dFlFFF/dAFM approaches 1 for small ion-coated NMs, which can be described as hard spheres, whereas dFlFFF/dAFM deviates from 1 for polymer-coated NMs, indicating that these particles are permeable, nonspherical, or both. These findings improve our understanding of the rather scattered data on NM size measurements reported in the environmental and nano(eco)toxicology literature and provide a tool for comparison of the measured sizes by different techniques.
Dispersity
Field-Flow Fractionation
Particle (ecology)
Nanomaterials
Multiangle light scattering
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