Synergic Effects of Surfactant and Chelating Agent on Stubborn Keratin Grime for Easy Cleaning.

We report on the synergic effect of surfactants and chelating agents on the mechanism to remove stubborn keratin grime (keratin-Ca), which is bound with calcium ions and one of the most difficult grimes to remove, in order to make it easier to clean bathtubs in less time and with less scrubbing. Our approach was to focus on keratin swelling, which we achieved by applying aqueous solutions with chelating agents and anionic surfactants, the combination of which greatly improved the swelling ratio, resulting in quick, easy removal of keratin-Ca with water rinsing and little scrubbing. For the swelling process, we added chelating agents and anionic surfactants to swell the keratin-Ca by both capturing calcium ions and improving solution permeation. Furthermore, we measured the structural change of the keratin-Ca during swelling by TD-NMR and confirmed that a certain combination of chelating agent and anionic surfactant improved swelling by affecting not only the amorphous part such as the keratin matrix, but also the crystalline part such as the intermediate filaments (IFs).

Structural Viscosity Induced by Depletion Effect in Stable Vesicle Dispersion.

Producing structural viscosity in colloidal dispersions, such as vesicles and capsules, prevents separation of dispersed particles by increasing the viscosity between them, which is advantageous in terms of usability. So far, the separation behavior of various particles has been studied; however, there are very few examples wherein a stable dispersion state was constructed and controlled. In this study, we produced stable dispersions induced by the depletion effect in mixtures of vesicles of cationic surfactant derived from triethanolamine-based esterquat (TEQ) and a specific dextrin derivative (SDD) as a non-adsorptive polymer. In the composition region, where 8 to 16% of TEQ vesicles and 1.2% or less of SDDs were mixed, the viscosity increased proportionally with the particle concentration, and it was observed that stable dispersions were produced by structural viscosity. Furthermore, the effects of TEQ and SDD concentrations, and SDD size on the structural viscosity and cohesive energy were investigated, which were similar to the depletion effect in the Asakura-Oosawa (AO) theory. From the results, it was suggested that the structural viscosity of the mixed dispersions (TEQ vesicles and SDDs) was produced by the aggregated TEQ vesicle networks induced by the depletion flocculation.

The nanostructure of murine alveolar bone and its changes due to type 2 diabetes.

Alveolar bone - the bony ridge containing the tooth sockets - stands out by its remodeling activity where bone is being formed and resorbed at a much higher rate than in any other bony tissue. Teeth that are anchored in the jaw through the periodontal ligament exert very large localized loads during mastication that could lead to a unique adaptation of the collagen/mineral structure in the bone. Our aim was to characterize the nanostructure of alveolar bone and to determine the influence of diabetes on structural characteristics of the mineralized matrix. Using small- and wide-angle X-ray scattering (SAXS/WAXS), we studied a spontaneous diabetic mouse model (KK+) and its corresponding healthy controls (KK-) (n=6) to determine the size and mutual alignment of the mineral nanoparticles embedded in the collagen matrix. On cross-sections (buccal-lingual) of the first molar multiple line scans with a spatial resolution of 30µm were performed on each sample, from the lingual to the buccal side of the mandible. Mineral particle thickness and length are decreasing towards the tooth in both buccal and lingual sides of alveolar bone. While mineral particles are well aligned with the long axis of the tooth on the buccal side, they are in a quarter of the measurements oriented along two preferred directions on the lingual side. These nanostructural differences can be interpreted as the result of an asymmetric loading during mastication, leading to a tilting of the tooth in its socket. In diabetic mice particle thicknesses are smaller compared to control animals.

Scattering and Spectroscopic Study on the Hydration and Phase Behavior of Aqueous Alcohol Ethoxylate and Methyl Ester Ethoxylate: Effects of Terminal Groups in Hydrophilic Chains.

Using dielectric relaxation spectroscopy (DRS), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and viscometry, we have investigated the hydration behavior, static structures, Brownian dynamics, and mechanical properties of aqueous solutions of alcohol ethoxylate (C12E15) and methyl ester ethoxylate (C12MEE), hereafter abbreviated as AE and MEE, respectively, in which we especially focus on the effects of the endcaps of these nonionic surfactants. We find that AE and MEE exhibit fairly different phase behaviors in water: AE produces liquid crystalline phases at w (surfactant weight fraction) > 0.35, whereas MEE retains a liquid phase in an extremely wide concentration range (w < 0.7) at ambient temperature. The structure factor deduced from SAXS intensities using a generalized indirect Fourier transformation technique and the effective hydration number evaluated from the negative excess bulk water relaxation amplitude revealed by DRS unambiguously demonstrate that hydration water molecules, exhibiting about 4-times-slower collective reorientational dynamics than that of bulk water, contribute to the excluded volume of the micelles. The blocked terminal hydrogen-bond donor/acceptor site of MEE leads to smaller hydration number of MEE than compared to that of AE, and consequently the lower excluded volume of the MEE micelles. The effective micellar volume fraction, ϕ(eff), should be defined by incorporating such different hydration effects. Importantly, voluminosity, defined as the micellar volume fraction per unit mass, is clearly a decreasing function of w, demonstrating progressive dehydration at a higher w. The collective diffusion constants determined by DLS for the AE and MEE micelles show a monotonous increase up to ϕ(eff) ≈ 0.5, as expected for the hard spheres. Low-shear-rate viscosities follow a Krieger-Dougherty model in the identical micellar packing fraction range. All static, dynamic, and mechanical properties of these micellar solutions can be explained in a consistent and quantitative manner only when the excluded volume of hydration water molecules is properly taken into account.

Structural analysis and adsorbability onto the corneal epithelial cells-model interface of vitamin nano-emulsions.

O/W nano-emulsions can be used as effective drug carriers of hydrophobic active ingredients in an aqueous solution, because nano-emulsions are comparatively stable and their structure can be controlled by changing the compositions and the preparation methods. In this paper, we focused on vitamin A and its derivatives (VA), which are among the widely-used lipophilic active ingredients, and tried to develop the nano-emulsions, which can bring out the efficiency of VA for the healing of injured corneas, with the detailed structural analysis of them using the small-angle X-ray scattering (SAXS) method. As a result, we elucidated that the nano-emulsions bearing the hydrophobic oil/water interface can be prepared by decreasing the surfactant concentration against vitamins. Moreover, we clarified that the nano-emulsions composed of lower surfactant concentration tend to adsorb VA onto the corneal epithelial cells-model interface. Therefore it is necessary to prepare the nano-emulsions, which have the hydrophobic oil/water interface for improving the adsorbability onto cell membranes.

Location of cholesterol in liposomes by using small-angle X-ray scattering (SAXS) data and the generalized indirect Fourier transformation (GIFT) method.

We investigated the location of cholesterol (Chol) in liposomes and its interaction with phospholipids using small-angle x-ray scattering (SAXS) data and applying the generalized indirect Fourier transformation (GIFT) method. The GIFT method has been applied to lamellar liquid crystal systems and it gives quantitative data on bilayer thickness, electron density profile, and membrane flexibility (Caillé parameter). When the GIFT method is applied to the SAXS data of dipalmitoylphosphatidylcholine (DPPC) alone (Chol [-]) or a DPPC/Chol = 7/3 mixed system (Chol [+], molar ratio), change in the bilayer thickness was insignificant in both systems. However, the electron density for the Chol (+) system was higher than that for the Chol (-) system at the location of hydrophilic groups of phospholipids, and whereas Caillé parameter value increased with temperature for the Chol (-) system, no significant change with temperature was observed in the Caillé parameter for the Chol (+) system. These results indicated that Chol is located in the vicinity of the hydrophilic group of the phospholipids and constricts the packing of the acyl chain of phospholipids in the bilayer.