Polypseudorotaxane-based supramolecular hydrogels consisting of cyclodextrins and Pluronics as stabilizing agents for antibody drugs.

Recently, antibody drugs have been used worldwide, and based on worldwide sales, 7 of the top 10 pharmaceutical products in 2019 were antibody-based drugs. However, antibody drugs often form aggregates upon thermal and shaking stresses with few efficient stabilizing agents against both stresses. Herein, we developed polypseudorotaxane (PpRX) hydrogels consisting of cyclodextrins (CyDs) and polyethylene glycol (PEG)-polypropylene glycol (PPG)-PEG block copolymers (Pluronics F108, F87, F68, and L44), and evaluated their utility as antibody stabilizing agents.

Effect of the Crystallization Process of Surfactant Bilayer Lamellar Structures on the Elongation of High-Aspect-Ratio Gold Nanorods.

The growth mechanism of an "in-gel synthesis method", that is, the effects of composition and structure of the lamellar gel phase below the Krafft temperature of surfactant solutions on the growth of long gold nanorods, was investigated. We changed the alkyl chain length of surfactant molecules to investigate the effect of surfactant self-assembly on the elongation of gold nanorods systematically; eight mixed solutions of alkyltrimethylammonium bromide (C nTAB; n = 2-16; n = even) with C18TAB were used for investigation. The Krafft temperature, self-assembly of surfactant molecules, and the crystallization process of each mixture were observed by differential scanning calorimetry, wide-angle X-ray scattering, visual inspection, and small-angle X-ray scattering.

Effects of Oscillatory Shear on the Orientation of the Inverse Bicontinuous Cubic Phase in a Nonionic Surfactant/Water System.

The bicontinuous inverse cubic phase (V2 phase) formed in amphiphilic systems consists of bilayer networks with a long-range order. We have investigated effects of oscillatory shear on the orientation of the V2 phase with space group Ia3d formed in a nonionic surfactant (C12E2)/water system by using simultaneous measurements of rheology/small-angle X-ray scattering. It is shown that grain refining occurs by applying the large amplitude oscillatory shear (LAOS) with a strain amplitude (γ0) of ∼20, which gives the ratio of the loss modulus (G″) to the storage modulus (G') (G″/G' = tan δ) of ∼100.

Pressure-Induced Transition of Bilayers in a Nonionic Surfactant Solution.

Pressure effects on the bilayers of polyoxyethylene type nonionic surfactant in water have been investigated by means of small- and wide-angle X-ray scattering. It has been found that the Krafft transition from the micellar phase to the lamellar gel phase (Lβ) is induced by pressure. By further pressurizing, the lamellar structural parameters, such as the repeat distance d and Caillé parameter η, discontinuously decrease after taking a maximum.

Mesoscopic simulation of phase behaviors and structures in an amphiphile-solvent system.

We have performed a three-dimensional simulation of mesoscopic structures in a mixture of AB amphiphilic molecule and C solvent by employing the density-functional theory under the conditions that (i) the size of the AB is much larger than C and (ii) the affinity between A and B is much larger than the affinity between B and C. First, we have calculated the free energy of five periodic structures, i.e.

Electrolyte effect on lamellar domain morphology in a nonionic surfactant solution below the Krafft temperature.

In our previous papers, we have studied the lamellar domain morphology in aqueous solutions of nonionic surfactants C16E6 and C16E7 below the Krafft temperature. In this study, electrolyte effects on lamellar domain morphology have been investigated by means of DSC, confocal microscope, small/wide-angle X-ray scattering (SAXS/WAXS). It has been found that vesicles in C16E7 solution are transformed to network structures by adding chaotropic ion Cl(-), F(-) and CH3COO(-), whereas the network structures in C16E6 solution are gradually changed to the vesicles with increasing kosmotropic ion SCN(-) concentration.

Effects of surfactant concentration on formation of high-aspect-ratio gold nanorods.

The effects of surfactant concentration in a growth solution on the elongation of gold nanorods were examined. Gold nanorods were synthesized in solutions with different concentrations of hexadecyltrimethylammonium bromide (HTAB): 100, 200, 300, 400, 500, and 600 mM. The nanorods grown in a solution with higher surfactant concentrations were longer (aspect ratio ~30) than those grown in that with lower concentrations (aspect ratio <10).

Re-entrant lamellar/onion transition with varying temperature under shear flow.

We have found for the first time the reentrant lamellar/onion (lamellar-onion-lamellar) transition with varying temperature under constant shear rate by using simultaneous measurements of shear stress and small-angle X-ray scattering (Rheo-SAXS) for a nonionic surfactant (C(14)E(5))/water system, which exhibits the lamellar phase in a wide temperature range from 15-75 °C. The onion state exists in a closed region in the temperature-concentration diagram at a constant shear rate. Temperature dependence of the lamellar repeat distance (d) at rest has also been measured at several concentrations.

Microscopic investigation on morphologies of bilayer gel structure in the mixed polyoxyethylene-type nonionic surfactant systems.

We investigated morphologies of lamellar domains below the Krafft temperature in the mixed polyoxyethylene-type nonionic surfactant, a C(16)E(6)/C(16)E(7)/water system, by using optical microscopy, confocal microscopy, small/wide-angle X-ray scattering, and small-angle neutron scattering. We have found that the morphology discontinuously changes from network structures of lamellar domains to spherical vesicles with increasing mole fraction of C(16)E(7), via the coexistence region of vesicles and network structures of lamellar domains.

3D structure of lamellar domains in a surfactant solution below the Krafft temperature.

We have studied the 3D structure of lamellar domains in aqueous solutions of nonionic surfactant C(16)E(6) and C(16)E(7) below the Krafft temperature by means of confocal microscopy. A new morphology of lamellar domains has been found in the C(16)E(6) system, which is the network of lamellar domains. In the C(16)E(7) system, we have confirmed that the spherical vesicles have a hollow including excess water.

Transition processes from the lamellar to the onion state with increasing temperature under shear flow in a nonionic surfactant/water system studied by Rheo-SAXS.

In a previous paper, we reported for the first time the lamellar-to-onion transition with increasing temperature at around 67 °C under a constant shear rate (0.3-10 s(-1)) in a nonionic surfactant C(16)E(7)/water system. In this study, the first temperature-shear rate diagram has been constructed in a wider range of shear rate (0.

Vesicle growth and deformation in a surfactant solution below the Krafft temperature.

We have studied vesicle growth and deformation in aqueous solutions of nonionic surfactant C(16)E(7) below the Krafft temperature by means of an optical microscope. It has been found that vesicles become larger by fusing together, and that the growth rate is slower than that of the unilamellar vesicle or emulsion systems due to the multilamellar structures of shells in a vesicle. The deformation of the vesicles depends on the temperature quench depth, and we found the transformation from spherical vesicles to string-like domains at a certain quench-temperature.

Lamellar-to-onion transition with increasing temperature under shear flow in a nonionic surfactant/water system.

Simultaneous measurements of small-angle light scattering/shear stress (Rheo-SALS) and small-angle X-ray scattering/shear stress (Rheo-SAXS) have been performed in the lamellar phase of the C(16)E(7)/D(2)O system. As the temperature is increased and exceeds 67 degrees C at constant shear rates (at 1 and 3 s(-1)), the shear stress increases abruptly and a four-lobe pattern is observed in the depolarized SALS. These results suggest that the lamellar-to-onion transition occurs with increasing temperature, which has not yet been reported.

Formation process of bilayer gel structure in a nonionic surfactant solution.

We investigated the structure and formation process of lamellar domains below the Krafft temperature in two nonionic surfactants, the C(16)E(7)/water and C(16)E(6)/water systems, using an optical microscope and small-angle X-ray scattering. We found that vesicles and long leek-like lamellar domain structures are formed in the C(16)E(7) and C(16)E(6) systems, respectively. This large difference between the lamellar domain structures of the systems can be explained by the elastic properties of bilayers in the structural formation process.

Pressure effects on bending elasticities of surfactant monolayers in a ternary microemulsion composed of aerosol-OTD2O/decane.

Pressure effects on the bending elasticities of surfactant monolayers have been investigated in a microemulsion system composed of aerosol-OT (AOT), D2O, and deuterated decane by means of small angle neutron scattering, neutron spin echo (NSE), and dynamic light scattering (DLS). In this system, a water-in-oil droplet structure, at ambient temperature and pressure, decomposes into two phases, under both increasing temperature and pressure. The authors' previous study showed that the bending modulus kappa of monolayers slightly decreased with increasing temperature, while it increased with increasing pressure.

Micelle structures in aqueous solutions of glucose-based surfactants having an isoprenoid-type hydrophobic chain.

Surfactant self-diffusion coefficients have been measured on a binary system of 1-O-beta-3,7-dimethyloctyl-D-maltopyranoside (beta-Mal(2)(Ger))/water and a mixed surfactant system of beta-Mal(2)(Ger)/1-O-beta-3,7-dimethyloctyl-D-glucopyranoside (beta-Glc(Ger))/water at 25 degrees C. For comparison, measurements have also been made on 1-O-beta-decyl-D-maltopyranoside (beta-Mal(2)C(10))/water and beta-Mal(2)C(10)/1-O-beta-decyl-D-glucopyranoside (beta-GlcC(10))/water. The hydrodynamic radius of beta-Mal(2)(Ger) micelles obtained from the micellar diffusion coefficient is around 3 nm and nearly equal to that of beta-GlcC(10) micelles within experimental error.

Anomalous decrease in lamellar spacing by shear flow in a nonionic surfactant/water system.

We study the effects of shear flow on the structure of a lamellar phase in a C16E7 [hepta(oxyethylene glycol)-n-hexadecyl ether]/water system (40-55 wt % of C16E7) at 70 degrees C using small-angle neutron scattering in the range of shear rate of 10(-3)-30 s(-1). At the shear rate 0.1-1 s(-1), the repeat distance (d) is decreased significantly (down to about 40% of d at rest in the most significant case) and discontinuously with increasing shear rate.