A-ring oxidation products from γ-irradiation of cholesterol in liposomes

γ-Irradiation of cholesterol in multilamellar vesicles (MLV) at 0–4°C causes oxidation of the A-ring. Two A-ring oxides formed in considerable amounts are cholest-4-en-3-one (10) and cholest-4-ene-3,6-dione (12) in addition to the usual B-ring oxides. Lesser amounts of cholesta-4,6-dien-3-one (11) are also generated. Compounds 10 and 12 were detected and measured in cholesterol irradiated at less than 0.5 kGy in liposomes containing saturated or unsaturated phospholipids. Lesser amounts of 10 and 12, as well as lesser amounts of other cholesterol oxides, were formed when a major constituent of the MLV was dilinoleoylphosphatidylcholine. Autoxidation of cholesterol in MLV also gave rise to small amounts of 10, 11 and 12.     

化妆品科学的新技术及展望

介绍了未来化妆品工业中可能应用到的两个新技术--纳米技术和射频鉴别（RFID）标签.对纳米技术和射频鉴别标签对未来化妆品科学可能产生的影响进行了讨论.     

Dispersions of lamellar phases of non-ionic lipids in cosmetic products

Although aqueous dispersions of lipids in the form of particles having a lamellar structure (liposomes) are already known as excellent vehicles for pharmaceutical substances, their usefulness in cosmetic formulations has not been demonstrated. The present work shows the advantages obtained by application of such systems to the skin, and in particular the use of non-ionic lipids in aqueous dispersions. Thus, in comparison with classical formulations such as emulsions, these systems exhibit lower toxicity and permit closer control of the availability of active substances at the stratum corneum. As examples, compositions suitable for skin moisturising and for tanning products are presented. Dispersions de phases lamellaires de lipides non-ioniques en cosmétique     

The antibacterial activity and antibacterial mechanism of the tea polyphenol liposomes/lysozyme–chitosan gradual sustained release composite coating

To obtain long-lasting preservation materials, the tea polyphenol liposomes (TP-Lips)/lysozyme (LZM)–chitosan (CS) composite coating with the gradual sustained property was prepared by tape casting method. These coatings were characterised, and their physicochemical properties were measured. Meanwhile, the antibacterial mechanisms of coatings were studied using the spoilage bacteria of aquatic products (Shewanella putrefaciens and Pseudomonas fluorescens) as target strains. Compared with CS coating, the incorporation of TP-Lips makes the cracks and granular matter of the coatings increase. Except for the oxygen permeabilities (OP) and carbon dioxide permeabilities (CDP), the rest of the physicochemical properties are decreased, including tensile strength (Ts), elongation at break (EB) and light transmittance (T). Antibacterial mechanisms indicate that TP and LZM have a synergistic antibacterial effect. The slow-release system composed of liposomes and coating prolongs the action time of TP and LZM. Hence, the TP-Lips/LZM-CS coating could be a hopeful material in food preservation field with excellent antibacterial properties.     

Microemulsion Synthesis of Superparamagnetic Nanoparticles for Bioapplications

Superparamagnetic nanoparticles have seen increased potential in medical and environmental applications. Their preparation is traditionally made by the coprecipitation method, with limited control over the particle size distribution. Microemulsion methods could be advantageous due to the efficient control of the size, shape, and composition of the nanoparticles obtained. Water-in-oil (W/O) microemulsions consist of aqueous microdomains dispersed in a continuous oil phase, stabilized by surfactant molecules. These work as nanoreactors where the synthesis of the desired nanoparticles takes place through a co-precipitation chemical reaction. In this work, superparamagnetic magnetite nanoparticles with average diameters between 5.4 and 7.2 nm and large monodispersity have been synthesized through precipitation in a W/O microemulsion, with Cetyl Trimethyl Ammonium Bromide (CTAB) as a main surfactant, 1-butanol as a cosurfactant, and with 1-hexanol as the continuous oily phase. The optimization of the corresponding washing protocol has also been established since a strict control is required when using these materials for bioapplications. Their applicability in those has been proved by their encapsulation in liposomes, being tested as signal enhancers for lateral flow immunoassays by using the affinity neutravidin-biotin model system. Due to their magnetic behaviour, they were also tested for magnetic separation. These novel materials have been found to be useful for analytical applications requiring high sensitivity and the removal of interferences.     

Amino‐terminated polylactide micelles with an external poly(ethylene oxide) corona as carriers of drug‐loaded anionic liposomes

Micelles were prepared from a mixture of NH₂‐terminated poly(l ‐lactide) and poly(d ,l ‐lactide)‐block‐poly(ethylene oxide) (molar ratio of 3:7). The micelles were complexed with bilayer lipid vesicles (liposomes) composed of anionic palmitoyloleoylphosphatidylserine and zwitterionic dioleoylphosphatidylcholine in a molar ratio of 3:7. The micelles and micelle–liposome complexes were characterized using dynamic light scattering, laser electrophoresis, fluorimetry, transmission electron microscopy, enzymatic hydrolysis and cell viability with the following main findings. (i) Average diameter of micelle cores was found to be 70 ± 10 nm. (ii) Each micelle carried ca 20 000 amino groups. (iii) In a pH 7 solution the impact of the protonated NH₂ groups in the total surface of micelles was negligible owing to their screening by bulky poly(ethylene oxide) blocks. (iv) The micelles were stable in slightly acidic and neutral aqueous solutions, but aggregated in slightly alkaline solutions. (v) The micelles showed no cytotoxicity up to 0.04 mg mL^?1 concentration (the maximum concentration in the experiment). (vi) Each micelle adsorbed ca 30 anionic liposomes loaded with the antitumor antibiotic doxorubicin; the liposomes retained their integrity upon binding with micelles. (vii) The initial micelles and the micelle–liposome complexes showed two‐week stability to enzymatic hydrolysis. © 2018 Society of Chemical Industry     

Elastic liposomes-in-vehicle formulations destined for skin therapy: the synergy between type of liposomes and vehicle

Objective: The present study is focused on optimization of elastic liposomes-in-vehicle formulations in respect to drug release and formulation properties. By combining penetration potential of elastic liposomes containing high ratio of entrapped drug and physicochemical properties of vehicles, both affecting the release and texture properties, optimal formulation could be achieved.

Materials and methods: Deformable, propylene glycol-containing or conventional liposomes with hydrophilic model drug (diclofenac sodium) were incorporated into the following vehicles appropriate for skin application: a hydrogel, a cream base and derma membrane structure base cream (DMS base). Each formulation was assessed for in vitro drug release and mechanical properties.

Results and discussion: The composition and type of both liposomes and the vehicle affected the rate and amount of the released drug. The cream base exhibited the slowest release, followed by the hydrogel and DMS base. Similar release profiles were achieved with both types of elastic vesicles (deformable and propylene glycol liposomes); the slowest release was observed for conventional liposomes, regardless of the vehicle used. The drug release profiles from different liposomes-in-vehicle formulations were in agreement with the physicochemical properties of the formulations. All of the liposomes were found to be compatible with the hydrogel preserving its original textures, whereas a significant decrease in all texture parameters was observed for liposomes-in-DMS base, regardless of liposome type.

Conclusion: Propylene glycol liposomes-in-hydrogel is considered as the optimal formulation for improving skin delivery of hydrophilic drug. Further investigations involving in vivo animal studies are necessary to confirm its applicability in skin therapy.     

Tuning Cerium(IV)‐Assisted Hydrolysis of Phosphatidylcholine Liposomes under Mildly Acidic and Neutral Conditions

With the goal of designing a lysosomal phospholipase mimic, we optimized experimental variables to enhance Ce^IV‐assisted hydrolysis of phosphatidylcholine (PC) liposomes. Our best result was obtained with the chelating agent bis–tris propane (BTP). Similar to the hydrolytic enzyme, Ce^IV‐assisted hydrolysis of PC phosphate ester bonds was higher at lysosomal pH (～4.8) compared to pH 7.2. In the presence of BTP, the average cleavage yield at ～pH 4.8 and 37 °C was: 67±1 %, 5.7‐fold higher than at ～pH 7.2 and roughly equivalent to the percent of phospholipid found on the metal‐accessible exo leaflet of small liposomes. No Ce^IV precipitation was observed. When BTP was absent, there was significant turbidity, and the amount of cleavage at ～pH 4.8 (69±1 %) was 2.1‐fold higher than the yield obtained at ～pH 7.2. Our results show that BTP generates homogenous solutions of Ce^IV that hydrolyze phosphatidylcholine with enhanced selectivity for lysosomal pH.