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The Span 40 (sorbitan monooleate)/Tween 40 (polyoxyethylene sorbitan monolaurate) system gives faceted vesicles with angular surfaces, rather than spherical vesicles. Herein, a continuous and facile preparation method, based on the subcritical water-assisted emulsification and solvent diffusion, was presented to yield faceted vesicles with two major and minor axes (Type A) and vesicles closer to a polyhedron (Type B). Type A, rather than Type B, vesicles were likely to be formed. From the measurements concerning ζ-potential, membrane fluidity, and the polarization environment of the membranes, faceted vesicles could be obtained at 0.25 wt% of the surfactant concentration. The phase-separated behavior of Span 40 and Tween 40 within vesicle membranes could explain the structural feature of faceted vesicles and calcein leakage behavior. The significant advantage is that Type A vesicles would be utilized as alternative drug carriers for others with low encapsulation efficiency, although the present technical limitations cause difficulty in the selective formation of Type A and B vesicles and the selection of adequate solvent to accelerate the solvent diffusion step. [ABSTRACT FROM AUTHOR]

A reduction reaction of 5-hydroxymethylfurfural to 2,5-dimethylfuran (2,5-DMF) has been previously performed in an organic solvent under high-temperature conditions. For the relaxation of such reaction conditions, conventional palladium on carbon (Pd/C) was combined with vesicles composed of phospholipids or surfactants. Pd/C combined with 1,2-dioleoyl-sn-glycero-3-phosphocholine indicated a yield (25%) at 60 °C compared with Pd/C (17%). Vesicles at the liquid crystalline phase were advantageous for the reduction reaction of HMF. The yield of 2,5-DMF catalyzed by Pd/C combined with the vesicles depended on the lipid composition of the vesicles. It was clarified that the yield of 2,5-DMF could be controlled by the hydration property of the vesicles. Compared with conventional 2,5-DMF synthesis in an organic solvent, the use of vesicles made it possible to reduce the burden of using organic solvents in high-temperature conditions, although limitedly. [ABSTRACT FROM AUTHOR]

Featured Application: Biocompatible materials in artificial organs, biosensors, or modifiers for a vehicle in a drug delivery system. The design of biosensors and artificial organs using biocompatible materials with a low affinity for amyloid β peptide (Aβ) would contribute to the inhibition of fibril growth causing Alzheimer's disease. We systematically studied the amyloidogenicity of Aβ on various planar membranes. The planar membranes were prepared using biocompatible polymers, viz., poly(methyl methacrylate) (PMMA), polysulfone (PSf), poly(L-lactic acid) (PLLA), and polyvinylpyrrolidone (PVP). Phospholipids from biomembranes, viz., 1,2-dioleoyl-phosphatidylcholine (DOPC), 1,2-dipalmitoyl-phosphatidylcholine (DPPC), and polyethylene glycol-graft-phosphatidyl ethanolamine (PEG-PE) were used as controls. Phospholipid- and polymer-based membranes were prepared to determine the kinetics of Aβ fibril formation. Rates of Aβ nucleation on the PSf- and DPPC-based membranes were significantly higher than those on the other membranes. Aβ accumulation, calculated by the change in frequency of a quartz crystal microbalance (QCM), followed the order: PSf > PLLA > DOPC > PMMA, PVP, DPPC, and PEG-PE. Nucleation rates exhibited a positive correlation with the corresponding accumulation (except for the DPPC-based membrane) and a negative correlation with the molecular weight of the polymers. Strong hydration along the polymer backbone and polymer–Aβ entanglement might contribute to the accumulation of Aβ and subsequent fibrillation. [ABSTRACT FROM AUTHOR]

To facilitate the early diagnosis of Alzheimer's disease and mild cognitive impairment patients, we developed a cantilever‐based microsensor that immobilized liposomes of various phospholipids to detect a trace amount of amyloid β (Aβ) protein, and investigated its aggregation and fibrillization on model cell membranes in human serum. Three species of liposomes composed of different phospholipids of 1,2‐dipalmtoyl‐sn‐glycero‐3‐phosphocholine (DPPC), DPPC/phosphatidyl ethanolamine and 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphorylglycerol having varied hydrophilic groups were applied, which showed different chronological interactions with Aβ(1–40) protein and varied sensitivities of the cantilever sensor, depending on their specific electrostatic charged conditions, hydrophilicity, and membrane fluidity. 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphocholine (DMPC) having short hydrophobic carbon chains confirmed to show a large interaction with Aβ(1–40) and a high sensitivity. Furthermore, the incorporation of cholesterol into DMPC was effective to selectively detect Aβ(1–40) in human serum, which effect was also checked by quartz crystal microbalance. Finally, Aβ detection of 100‐pM order was expected selectively in the serum by using the developed biosensor. [ABSTRACT FROM AUTHOR]

Membrane lipid composition is known to influence aggregation and fibril formation of many amyloidogenic proteins. Here, we found that phosphatidylethanolamine (PE) accelerates aggregation of the N‐terminal 1‒83 fragment of an amyloidogenic G26R variant of apoA‐I on lipid membranes. Circular dichroism and isothermal titration calorimetry measurements demonstrated that PE does not affect the α‐helical structure and lipid binding property of apoA‐I 1‐83/G26R. Rather, fluorescence measurements indicated that PE induces more ordered lipid packing at the interfacial and acyl chain regions, providing more hydrophobic environments especially around the highly amyloidogenic regions in apoA‐I on the membrane surface. These results suggest that PE promotes aggregation of the amyloidogenic N‐terminal fragment of apoA‐I on lipid membranes by inducing hydrophobic membrane environments. [ABSTRACT FROM AUTHOR]

The objective of this review is to survey the development of the optimization of lyophilization. The optimization study of the lyophilizer has been roughly developing by the order of (i) trial-and-error approach, (ii) process modeling using mathematical models, (iii) scalability, and (iv) quality-by-design. From the conventional lyophilization studies based on the trial-and-error, the key parameters to optimize the operation of lyophilization were found out, i.e., critical material attributes (CMAs), critical process parameters (CPPs), and critical quality attributes (CQAs). The mathematical models using the key parameters mentioned above have been constructed from the viewpoints of the heat and mass transfer natures. In many cases, it is revealed that the control of the primary drying stage determines the outcome of the lyophilization of products, as compared with the freezing stage and the secondary drying stage. Thus, the understanding of the lyophilization process has proceeded. For the further improvement of the time and economical cost, the design space is a promising method to give the possible operation range for optimizing the lyophilization operation. This method is to search the optimized condition by reducing the number of key parameters of CMAs, CPPs, and CQAs. Alternatively, the transfer of lyophilization recipe among the lab-, pilot-, and production-scale lyophilizers (scale-up) has been examined. Notably, the scale-up of lyophilization requires the preservation of lyophilization dynamics between the two scales, i.e., the operation of lab- or pilot-scale lyophilizer under HEPA-filtrated airflow condition. The design space determined by focusing on the primary drying stage is large and involves the undesired variations in the quality of final products due to the heterogeneous size distribution of ice crystals. Accordingly, the control of the formation of the ice crystal with large size gave impact on the product quality and the productivity although the large water content in the final product should be improved. Therefore, the lyophilization should take into account the quality by design (QbD). The monitoring method of the quality of the product in lyophilization process is termed the "process analytical technology (PAT)." Recent PAT tools can reveal the lyophilization dynamics to some extent. A combination of PAT tools with a model/scale-up theory is expected to result in the QbD, i.e., a quality/risk management and an in situ optimization of lyophilization operation. [ABSTRACT FROM AUTHOR]

The hydrolysis of disaccharides was conducted using a microcapillary system under hydrothermal conditions (up to 190°C at 10 MPa and pH 4–11). The hydrolysis reaction showed a sigmoidal progression with time, especially under alkaline conditions. Analysis using a kinetic model yielded the reaction induction period. The specific pH value (pHamb) at the induction time, which is the pH value corresponding to the progression of disaccharide hydrolysis, was peculiar to each disaccharide. Finally, the calculation of the electron density around the oxygen atom of the glycosidic bond between saccharides was found to roughly predict the pHamb value required for the progression of hydrolysis. [ABSTRACT FROM AUTHOR]