Using Microemulsions: Formulation Based on Knowledge of Their Mesostructure

Advances in the use of local anesthetic extended-release systems in pain management

Pain management remains among the most common and largely unmet clinical problems today. Local anesthetics play an indispensable role in pain management. The main limitation of traditional local anesthetics is the limited duration of a single injection. To address this problem, catheters are often placed or combined with other drugs in clinical practice to increase the time that local anesthetics act. However, this method does not meet the needs of clinical analgesics. Therefore, many researchers have worked to develop local anesthetic extended-release types that can be administered in a single dose. In recent years, drug extended-release systems have emerged dramatically due to their long duration and efficacy, providing more possibilities for the application of local anesthetics. This paper summarizes the types of local anesthetic drug delivery systems and their clinical applications, discusses them in the context of relevant studies on local anesthetics, and provides a summary and outlook on the development of local anesthetic extended-release agents.

Redox-switchable microemulsions with efficient phase separation and surfactant recycling

HYPOTHESIS

Switchable microemulsions (MEs) are those capable of adaptively responding to the action of internal or external stimuli. For redox-switchable MEs to obtain high-efficiency phase separation and surfactant recycling, it may be one of the keys to adequately turn off the interfacial activity of surfactants and reduce the solubility of the closed surfactants in the oil phase.

EXPERIMENTS

Monophasic MEs consisting 11-butylselanyl-undecyl sulfate sodium (C4SeC11SO4Na), n-butanol, n-octane, and water were fabricated using the pseudo-ternary phase diagram method. Their structural features and droplets size were characterized by conductivity, dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo-TEM), respectively. The redox response of MEs was studied using a combination of visual observations and DLS, cryo-TEM, nuclear magnetic resonance (NMR) and thin-layer tomography. The efficient recycling of C4SeC11SO4Na from a well-emulsified eluent is conceptually demonstrated.

FINDINGS

The reversible transition between C4SeC11SO4Na and C4SeOC11SO4Na is achieved under the alternating action of H2O2 and N2H4, by which C4SeC11SO4Na-based monophasic MEs are able to efficiently demulsify and regenerate, respectively, regardless of their type. After H2O2-induced demulsification of the MEs, C4SeOC11SO4Na can be efficiently recycled with the water phase. We hope that such a redox-switching method may benefit some technological applications. For example, it offers exciting possibilities for simultaneous recycling C4SeC11SO4Na and removal of oil from a well-emulsified eluent. Around 97.1 ± 0.3 % of C4SeC11SO4Na could be recycled over five cycles with no apparent loss. After a simple and conventional treatment with anion-exchange resin and active carbon, the total organic carbon and chemical oxygen demand of the waste water were 17.4 ± 2.8 and 26.2 ± 1.4 mg/L, respectively.

Probe into a novel surfactant-free microemulsion system of ethylene glycol monobutyl ether + water + diesel for crude oil removal and recovery from oily sludge

A novel surfactant-free microemulsion (SFME) system was proposed in this study, and applied in the crude oil removal and recovery from oily sludge (OS). Based on an investigation of the SFME phase behavior and solution properties, a complete ternary phase diagram was constructed. The SFME with three-liquid phase equilibrium (Winsor III type) was selected for the treatment of OS to achieve simultaneous efficient removal (up to 95.1 %) and recovery (up to 83.2 %) of crude oil. The SFME could be reused continuously for OS treatment without purification. The removal efficiency could still keep >75.9 % after 5 times of reuse, showing high reusability. The detached crude oil could be automatically recovered based on the phase equilibrium principle without additional separation. In the washing experiments, single-factor and multi-factor orthogonal tests were applied to investigate the effects of different experimental conditions on oil removal efficiency and determine the optimal experimental scheme. The treated OS was sufficiently decontaminated according to the morphology, composition, and properties analysis by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and contact angle. The composition of the recovered crude oil was identical to that of commercial crude oil according to gas chromatography-mass spectrometry analysis, showing a high recovery value. The kinetic analysis revealed that crude oil desorption experienced three main stages: membrane diffusion, intra-particle diffusion and surface desorption, and identified the chemisorption was the main interaction between the oil-soil. Finally, the mechanism of SFME action was assessed for dissolution and activation based on ultra-low IFT.

Interactive roles of co-solvents and lemon-oil composition in the fabrication of dilutable clear emulsions

Clear emulsions are used as flavor carriers by the beverage industry because of their favorable optical properties. A transparent microemulsion with small droplets requires a high concentration of surfactants, and is often non-dilutable, posing a significant challenge to their application in the food industry. The formation of dilutable microemulsions by modulating the compatibility of oil composition and co-solvents was studied. While single-fold lemon oil exhibited poor loading capacity overall, no precipitation occurred due to the stronger interaction between monoterpenes and sucrose monopalmitate (SMP). Conversely, emulsification of five-fold lemon oil with 20 % ethanol demonstrated a higher loading capacity and a stronger dilution stability than other lemon oils. This is likely due to the balanced composition of surface-active monoterpenes and other components in five-fold lemon oil which facilitated the effective use of micellar space and aided in the retention of both surfactants and co-solvents post-dilution. The emulsification of higher-folded lemon oil, however, was favored by the use of propylene glycol as a surfactant exhibiting stronger dilution stability than ethanol, though it required twice as much co-solvent. The high concentration of surface-active monoterpene in the lower-folded lemon oils competes with propylene glycol for interfacial incorporation. This study demonstrated that co-solvents and oil composition play interactive roles in producing dilutable optically clear emulsions, and it provides a blueprint for the food industry to design colloidal systems using a minimum of surfactants.

Quercetin encapsulation and release using rapid CO2-responsive rosin-based surfactants in Pickering emulsions

Emulsion-based delivery systems are extensively employed for encapsulating functional active ingredients, protecting them from degradation, and enhancing bioavailability and release efficiency. Here, a CO2-responsive surfactant synthesized from rosin displays rapid responsiveness to CO2 at room temperature, transitioning reversibly switches between active and inactive states multiple times. The dual tertiary amines on the rosin rigid structure contributes to its CO2 sensitivity. When in its active cationic form, in conjunction with silica nanoparticles, it exhibits desired Pickering emulsification performance across various oil phases. In the Pickering emulsion loaded with quercetin, the encapsulation efficiency and loading efficiency reached 80.50% and 0.69%, respectively, with stability lasting at least 30 days. The system provides robust protection for quercetin against external factors, such as UV and heat, revealing sustained release effects. This study investigated the potential of using rosin-based CO2-responsive surfactants alongside nanoparticles to design stable Pickering emulsion systems for active substance encapsulation and sustained release.

Surfactant Synergistic Effect and Interfacial Properties of Microemulsions Compounded with Anionic and Nonionic Surfactants Using Dissipative Particle Dynamics

Microemulsions are one of the most promising directions in enhanced oil recovery, but conventional screening methods are time-consuming and labor-intensive and lack the means to analyze them at the microscopic level. In this paper, we used the Clint model to predict the changes in the synergistic effect of the mixed system of anionic surfactant sodium dodecyl benzenesulfonate and nonionic surfactant polyethoxylated fatty alcohols (C12E6), generated microemulsions using surfactant systems with different mole fractions, and used particle size to analyze the performance and stability of microemulsions, analyze the properties and stability of microemulsions using particle size, and analyze the interfacial behaviors and changes of microemulsions when different systems constitute microemulsions from the point of view of mesoscopic microemulsion self-assembly behaviors by combining with dissipative particle dynamics. It has been shown that microemulsion systems generated from anionic and nonanionic surfactants with a synergistic effect, based on the Clint model, exhibit excellent performance and stability at the microscopic level. The method proposed in this paper can dramatically improve the screening efficiency of microemulsions of anionic and nonanionic surfactants and accurately analyze the properties of microemulsions, so as to provide a theoretical basis for the subsequent research on microemulsions.

Cosmetically Approved Short-Chain Alcohol/Triethyl Citrate/Water Surfactant-Free Microemulsions and Potential Application to Transdermal Penetration of α-Arbutin

Surfactant-free microemulsions (SFMEs) exhibited remarkable advantages and potential, attributed to their similarity to traditional surfactant-based microemulsions and the absence of surfactants. Herein, a novel SFME was developed utilizing cosmetically approved materials, such as short-chain alcohol as an amphi-solvent, triethyl citrate (TEC) as the nonpolar phase, and water as the polar phase. 1,2-Pentanediol (PtDO)/TEC/water combination can form the largest monophasic zone, accounting for ∼74% of the total phase diagram area, due to an optimal hydrophilic (water)-lipophilic (TEC) balance. Comparable to surfactant-based microemulsion, PtDO/TEC/water SFME can also be categorized into three types: water-in-oil, discontinuous, and oil-in-water. As TEC or water is increased, or PtDO is decreased, the nanoaggregates in PtDO/TEC/water SFME grow from <5 nm to tens of nanometers. The addition of α-arbutin (ABN) does not disrupt PtDO/TEC/water SFME, but rather enhances its formation, resulting in a larger monophasic area and consistent size (2.8-3.8 nm) through participating in interface assembly. Furthermore, ABN-loaded PtDO/TEC/water SFME exhibits remarkable resistance to dilution, exceptional stability, and minimal irritation. Notably, PtDO/TEC/water SFME significantly boosts ABN's solubility in water by 2 times, its percutaneous penetration rate by 3-4 times, and enables a slow-release DPPH• radical scavenging effect. This SFME serves as a safe and cosmetically suitable nanoplatform for the delivery of bioactive substances.

Enabling a novel solvent method on Albendazole solid dispersion to improve the in vivo bioavailability

Albendazole, a vital medication endorsed by the World Health Organization for combating parasitic infections, encounters a challenge stemming from its low solubility, significantly impeding absorption and bioavailability. Albendazole has near-insolubility in most organic solvents, so the solid dispersions of albendazole were predominantly using the fusion method. However, the solvent method could offer the advantage of achieving molecular-level mixing homogeneity. In this investigation, we incorporated the pH adjustment to prepare albendazole solid dispersion using a solvent method, which utilizes trace amounts of HCl in methanol, yielding notably enhanced albendazole solubility. Subsequently, carriers such as PEG6000/Poloxamer 188 (PEG: polyethylene glycol) and PVP K30/Poloxamer 188 (PVP: polyvinylpyrrolidone) were employed to create albendazole solid dispersions. Comprehensive characterization through dissolution rate analysis, PXRD (Powder X-ray diffraction), SEM (Scanning electron microscopy), DSC (differential scanning calorimetry), and pharmacokinetic (PK) studies in mice and rats was conducted. The findings indicate that the solid dispersion effectively transforms the crystalline state of albendazole into an amorphous state, resulting in significantly enhanced in vivo absorption and a 5.9-fold increase in exposure. Besides, the exposure increased 1.64 times of commercial albendazole tablets. Notably, PEG6000/Poloxamer 188 and PVP K30/Poloxamer 188 solid dispersions exhibited superior dissolution rates and pharmacokinetic profiles compared to commercially available albendazole tablets.

Exploring Microemulsion Systems for the Incorporation of Glucocorticoids into Bacterial Cellulose: A Novel Approach for Anti-Inflammatory Wound Dressings

The effective pharmacological treatment of inflamed wounds such as pyoderma gangraenosum remains challenging, as the systemic application of suitable drugs such as glucocorticoids is compromised by severe side effects and the inherent difficulties of wounds as drug targets. Furthermore, conventional semi-solid formulations are not suitable for direct application to open wounds. Thus, the treatment of inflamed wounds could considerably benefit from the development of active wound dressings for the topical administration of anti-inflammatory drugs. Although bacterial cellulose appears to be an ideal candidate for this purpose due to its known suitability for advanced wound care and as a drug delivery system, the incorporation of poorly water-soluble compounds into the hydrophilic material still poses a problem. The use of microemulsions could solve that open issue. The present study therefore explores their use as a novel approach to incorporate poorly water-soluble glucocorticoids into bacterial cellulose. Five microemulsion formulations were loaded with hydrocortisone or dexamethasone and characterized in detail, demonstrating their regular microstructure, biocompatibility and shelf-life stability. Bacterial cellulose was successfully loaded with the formulations as confirmed by transmission electron microscopy and surprisingly showed homogenous incorporation, even of w/o type microemulsions. High and controllable drug permeation through Strat-M® membranes was observed, and the anti-inflammatory activity for permeated glucocorticoids was confirmed in vitro. This study presents a novel approach for the development of anti-inflammatory wound dressings using bacterial cellulose in combination with microemulsions.

A dual-responsive microemulsion with macroscale superlubricity and largely switchable friction

Although stimuli-responsive microemulsions (MEMs) consisting of water, oil and surfactants have found extensive potential applications in industrial fields, a responsive MEM exhibiting either macroscale superlubricity or two friction states where its coefficient of friction (CoF) can be switched by more than one order of magnitude has not yet been reported. Moreover, although traditional liquid superlubricants can provide ultralow friction and wear, effective control over the friction between two contacting surfaces is crucial for both achieving accurate control of the operation of an instrument and fabricating smart devices. Here we create a thermo- and magneto-responsive MEM capable of providing superlubrication for metallic materials in a broad temperature range from -30 to 20 °C using n-hexane, water, surfactant DDACe ((C12H25)2N+(CH3)2[CeCl4]-) and ethylene glycol. The MEM can abruptly and dramatically switch its CoF by approximately 25 fold based on a thermally reversible MEM-emulsion (EM) transition. Its anti-freezing performance allows it to provide effective lubrication even when the surrounding temperature attains as low as -60 °C. Together with its facile preparation, ultrahigh colloidal stability and magnetically controlled migration, such a novel smart MEM is envisioned to find widespread applications in materials science.

Recent advances in synchrotron scattering methods for probing the structure and dynamics of colloids

Recent progress in synchrotron based X-ray scattering methods applied to colloid science is reviewed. An important figure of merit of these techniques is that they enable in situ investigations of colloidal systems under the desired thermophysical and rheological conditions. An ensemble averaged simultaneous structural and dynamical information can be derived albeit in reciprocal space. Significant improvements in X-ray source brilliance and advances in detector technology have overcome some of the limitations in the past. Notably coherent X-ray scattering techniques have become more competitive and they provide complementary information to laboratory based real space methods. For a system with sufficient scattering contrast, size ranges from nm to several μm and time scales down to μs are now amenable to X-ray scattering investigations. A wide variety of sample environments can be combined with scattering experiments further enriching the science that could be pursued by means of advanced X-ray scattering instruments. Some of these recent progresses are illustrated via representative examples. To derive quantitative information from the scattering data, rigorous data analysis or modeling is required. Development of powerful computational tools including the use of artificial intelligence have become the emerging trend.

Hierarchical Emulsion Structure and Functionality Regulated by Coexisting Bicontinuous Microemulsion and Liquid Crystal Domains

Since microemulsions are usually low viscosity fluids, enhanced rheological properties while maintaining their structure-derived functionality have long been desired from an industrial application point of view. However, for instance, it is practically difficult to thicken bicontinuous microemulsions (BCMEs) without perturbing their alternating domain structure or to emulsify oils using BCME having ultralow interfacial tension as an external phase. In this study, a methodology called a BCLC emulsification technique has been constructed to obtain oil-in-water emulsions stabilized by coexisting BCME and liquid crystal (LC) phases. The produced emulsions based on polyglyceryl-10 diisostearate, polyglyceryl-6 dicaprate, cetyl ethylhexanoate, and water are structurally scrutinized by means of small- and wide-angle X-ray scattering (SWAXS), freeze fracture transmission electron microscopy (FF-TEM), and scanning electron assisted dielectric microscopy (SE-ADM). The data provide experimental evidence that this methodology enables one to control the bending elasticity of the interfacial membranes and consequent long-range order of the BCME domains. Moreover, closely correlated with the interfacial membrane properties, submicrometer-sized fine oil droplets are supported by the LC networks and agglomerated into spongy or network-like phase-separation patterns. The resulting nonfluidic, jelly emulsions are particularly useful in cosmetics because of combined BCME-derived high cleansing performance and excellent usability owing to the enhanced viscosity. The thickening mechanisms are essentially different from those of common lamellar-gel-stabilized oil-in-water emulsions, which utilize crystalline lamellar gel networks as oil droplet stabilizers.

Development and Characterization of New Miconazole-Based Microemulsions for Buccal Delivery by Implementing a Full Factorial Design Modeling

This research aimed to develop miconazole-based microemulsions using oleic acid as a natural lipophilic phase and a stabilizer mixture comprising Tween 20 and PEG 400 to solubilize miconazole as an antifungal agent known for its activity in oral candidiasis and to improve its bioavailability. The formulation and preparation process was combined with a mathematical approach using a 23-full factorial plan. Fluid and gel-like microemulsions were obtained and analyzed considering pH, conductivity, and refractive index, followed by extensive analyses focused on droplet size, zeta potential, rheological behavior, and goniometry. In vitro release tests were performed to assess their biopharmaceutical characteristics. Independent variables coded X1-Oleic acid (%, w/w), X2-Tween 20 (%, w/w), and X3-PEG 400 (%, w/w) were analyzed in relationship with three main outputs like mean droplet size, work of adhesion, and diffusion coefficient by combining statistical tools with response surface methodology. The microemulsion containing miconazole base-2%, oleic acid-5%, Tween 20-40%, PEG 400-20%, and water-33% exhibited a mean droplet size of 119.6 nm, a work of adhesion of 71.98 mN/m, a diffusion coefficient of 2.11·10-5 cm2/s, and together with remarked attributes of two gel-like systems formulated with higher oil concentrations, modeled the final optimization step of microemulsions as potential systems for buccal delivery.

Effect of polymer addition on the phase behavior of oil-water-surfactant systems of Winsor III type

Ternary oil-water-surfactant systems can give rise to an O/W microemulsion in equilibrium with excess oil, a W/O microemulsion in equilibrium with excess water, or a bicontinuous microemulsion in equilibrium with excess oil and water. This type of phase behavior has been known for a long time and the three systems are often referred to as Winsor I, Winsor II and Winsor III, respectively after the British scientist P. A. Winsor who pioneered the area. The Winsor systems are technically important and well understood today. It was later found that addition of a polymer to the oil-water-surfactant system can influence the phase behavior considerably. While a hydrophilic polymer will be incorporated in the water phase and a hydrophobic polymer in the oil phase, an amphiphilic polymer with the right hydrophilic-lipophilic balance may expand the middle phase microemulsion in a Winsor III system. Expansion of the middle phase of such a system will lead to a reduction of the oil/microemulsion and the microemulsion/water interfacial tensions. This can be practically important, and the effect is currently of considerable interest for so-called surfactant flooding for enhanced oil recovery (EOR). Boosting the middle phase of the Winsor III system by addition of a polymer to the surfactant system is still not an established procedure and not so well understood from a scientific point of view. In this review we summarize the work done in the field and we demonstrate that the role of the polymer is intimately linked to its interactions with the three other components in the system: the oil, the water, and the surfactant(s).

A Study of Microemulsion Systems for Transdermal Delivery of Risperidone Using Penetration Enhancers

The aim of this study was to develop and characterize microemulsion formulations using penetration enhancers as potential transdermal delivery systems for risperidone. Initially, a simple formulation of risperidone in Propylene Glycol (PG) was prepared as a control formulation, together with formulations incorporating various penetration enhancers, alone and/or in combination, and also microemulsion formulations with various chemical penetration enhancers, were prepared and all were evaluated for risperidone transdermal delivery. An ex-vivo permeation study was carried out using human cadaver skin and vertical glass Franz diffusion cells to compare all the microemulsion formulations. The microemulsion prepared from oleic acid as the oil (15%), Tween 80 (15%) as the surfactant and isopropyl alcohol (20%) as the co-surfactant, and water (50%) showed higher permeation with a flux value of 32.50±3.60 ug/hr/sq.cm, a globule size of 2.96±0.01 nm, a polydispersity index of 0.33±0.02 and pH of 4.95. This novel in vitro research disclosed that an optimized microemulsion formulated using penetration enhancers was able to increase permeation of risperidone by 14-fold compared to the control formulation. The data suggested that microemulsions may be useful in the delivery of risperidone via the transdermal route.

Voltage-driven ion flux promotes emulsification at the water|oil interface

Emulsions are critical across a vast range of industries. Generally, emulsion synthesis is a complicated chemical process, requiring many mixed-phase systems. Here, we demonstrate that the flux of ions across the oil|water interface induces emulsification. Ion flux is achieved by a voltage-driven process, where an anode and a cathode are placed in each phase. When a current density of 2 mA cm-2 is reached across the interface, emulsification occurs. We demonstrate that emulsification can be tuned to occur in both phases, depending on the ions present. Droplet sizes are on the order of hundreds of nm and are stable for over an hour even without purposefully added surfactant. We demonstrate qualitative control over droplet size and charge based on salt content, current densities, and polarity of the interface. The process is 1000 times less energetic than ultrasonication. Our results introduce a robust and low-energy means of nanodroplet dispersion without the use of more than two phases and complex phase-transfer agents.

Self-assembly and structures of nanoscale double emulsion droplets through coarse-grained molecular dynamics simulations

Examples of self-assembled multiple emulsion droplets on the nanometre scale are very rare. In this work, we use coarse-grained (CG) molecular dynamics simulations to study the self-assembly of ternary mixtures consisting of water, n-heptane, and nonionic surfactant tetraethylene glycol monododecyl ether (C12E4). The water volume fractions studied are 1%, 3%, and 5%, respectively. Various nanoscale emulsions are obtained in a spontaneous process. When the water/surfactant volume ratio vm/s = 1.0/1.0, the obtained emulsion droplets are identified as oil-in-water-in-oil (O/W/O) double types, consisting of an oil core, an inner surfactant layer, a water layer, and an outer surfactant layer. The water molecules are distributed around the hydrophilic ends of the surfactants, while the hydrophobic ends of the surfactants wrap the oil cores and penetrate into the oil bulk. Hydrogen-bond interactions among water and the hydrophilic ends of the surfactants form cross-links that stabilize the double emulsion droplets. The sizes of all the oil cores inside the droplets are <6 nm in diameter, even with the highest water volume fraction of 5%. Both the concentration of free water molecules on the order of 10-6 mol/cm3 and the favourable energy change during emulsion formation indicate that the emulsion droplets are thermodynamically stable. In contrast, for vm/s = 1.0/5.5, no double emulsion but a simple water-in-oil emulsion was observed, with morphologies evolving from oblate to bicontinuous phases with an increase in the water volume fraction from 1% to 5%. Our coarse-grained molecular dynamics simulations provide valuable insight for the preparation of nanoscale double emulsions and the characterization of their structures.

A perspective of microemulsions in critical metal separation and recovery: Implications for potential application of CO2-responsive microemulsions

Since the discovery of microemulsions, they have attracted great attention due to its unique properties, such as ultra-low interfacial tension and nanoscale droplets. During the past several decades, microemulsions have shown unparalleled advantages in critical metal separation and recovery, e.g., high separation rate, high recovery efficiency, and good selectivity. Therefore, fundamental understandings of such metal recovery behavior are of great significance for the continuous development of microemulsion-based separation technology in this field. Herein, we first systematically reviewed the application of regular microemulsion in the separation and recovery process of critical metals focusing on their separation mechanisms. Then, we summarized the recent progress of CO2-responsive microemulsions and highlighted their potential application in critical metal separation and recovery, aiming to provide some insights into alleviating the difficulties in demulsification during the stripping stage using regular microemulsions. In this section, the latest development of CO2-responsive microemulsions is introduced, and the relationship between their composition, microstructure and macroscopic properties is discussed. Discussion and future perspectives are provided highlighting the design of new microemulsions and potential application of CO2-responsive microemulsions for metal separation and recovery in the future.

Structure of microemulsions in the continuous phase channel

We have studied the microemulsion and lamellar phases of two of the most commonly described systems based on nonionic C12E5 and ionic AOT surfactants. We show that C12E5 is best described by the symmetric disordered open connected lamellar model (DOC-lamellar), contrary to the more commonly employed standard flexible model. In the case of AOT, the bicontinuous microemulsion structure is best described by the standard flexible model at high temperatures. Around room temperature, connected cylinders in a molten cubic crystal phase are the only description which corresponds to the data. In the lamellar phase, around one third of the available surface area is lost in fluctuations and defects. Comparing structurally predictive models with results from conductivity measurements show that salt adsorption in the hydrated ethoxy groups is dominant for C12E5 (nonionic). For AOT, our conductivity measurements clarify the role of tortuosity versus cation absorption.

Recent advancement in bioeffect, metabolism, stability, and delivery systems of apigenin, a natural flavonoid compound: challenges and perspectives

Apigenin is a bioflavonoid compound that is widely present in dietary plant foods and possesses biological activities that protect against immune, cardiovascular, and neurodegenerative diseases and cancer. Therefore, apigenin is widely used in food and medicine, and increasing attention has been drawn to developing new delivery systems for apigenin. This review highlights the biological effects, metabolism, stability, and bioactivity of apigenin. In addition, we summarized advancements in the delivery of apigenin, which provides some references for its widespread use in food and medicine. Better stability of apigenin may enhance digestion and absorption and provide health benefits. Constructing delivery systems (such as emulsions, nanostructured lipid carriers, hydrogels, and liposomes) for apigenin is an effective strategy to improve its bioavailability, but more animal and cell experiments are needed to verify these findings. Developing apigenin delivery systems for food commercialization is still challenging, and further research is needed to promote their in-depth development and utilization.

Nano- and Microemulsions in Biomedicine: From Theory to Practice

Nano- and microemulsions are colloidal systems that are widely used in various fields of biomedicine, including wound and burn healing, cosmetology, the development of antibacterial and antiviral drugs, oncology, etc. The stability of these systems is governed by the balance of molecular interactions between nanodomains. Microemulsions as a colloidal form play a special important role in stability. The microemulsion is the thermodynamically stable phase from oil, water, surfactant and co-surfactant which forms the surface of drops with very small surface energy. The last phenomena determines the shortage time of all fluid dispersions including nanoemulsions and emulgels. This review examines the theory and main methods of obtaining nano- and microemulsions, particularly focusing on the structure of microemulsions and methods for emulsion analysis. Additionally, we have analyzed the main preclinical and clinical studies in the field of wound healing and the use of emulsions in cancer therapy, emphasizing the prospects for further developments in this area.

Impact of Processing Parameters on Contactless Emulsification via Corona Discharge

A contactless emulsification method is presented using corona discharge. The corona discharge forms using a pin-to-plate configuration, creating a non-uniform electric field. This results in a simultaneous electrohydrodynamic (EHD) pumping of silicone oil and an electroconvection of water droplets that accelerate and submerge inside the oil, leading to a continuous water-in-oil (W/O) emulsion formation process. The impact of the oil viscosity and corona generating AC and DC electric fields (i.e., voltage and frequency) on the characteristics of the emulsions is studied. The emulsification power consumption using the AC and DC electric fields is calculated and compared to traditional emulsion formation methods. While using the DC electric field results in the formation of uniform emulsions, the AC electric field is readily available and uses less power for the emulsification. This is facile, contactless, and energy-efficient for the continuous formation of W/O emulsions.

One-Pot Synthesis of 2D-2D WO3 /g-C3 N4 Photocatalyst in Reverse Microemulsion System via Supercritical CO2 for Enhanced Hydrogen Generation

Construction of Z-scheme photocatalyst is an effective approach for using solar energy to produce hydrogen during water splitting. Herein, 2D/2D WO₃ /g-C₃ N₄ heterojunction photocatalyst was synthesized by a convenient and green method including exfoliation and heterojunction procedures, in the reverse microemulsion system via supercritical carbon dioxide (scCO₂ ). The resultant W/CN-10.3 composite exhibited enhanced photocatalytic activities towards the hydrogen evolution during water splitting with a hydrogen evolution rate of 688.51 μmol g^-1  h^-1 , which was more than 16 times higher than bulk g-C₃ N₄ with the same loading amount of Pt as cocatalyst. Due to its effective separation of photogenerated carriers and prolonged lifetime, more photoexcited electrons with high reduction ability could contribute to the production of H₂ . Possible formation mechanism of 2D-2D WO₃ /g-C₃ N₄ nanosheets via scCO₂ in the reverse microemulsion system by the one-pot method has been proposed. This work provides an efficient and green strategy to synthesize 2D-2D heterojunction for the utilization in solar-to-fuel conversion.

Redox-responsive microemulsion: Fabrication and application to curcumin encapsulation

HYPOTHESIS

Stimulus-responsive microemulsions have aroused significant attention because of their versatile and reversible switchability between stable and unstable states. However, most stimuli-responsive microemulsions are based on stimuli-responsive surfactants. We posit that the change in the hydrophilicity of a selenium-containing alcohol triggered by a mild redox reaction could also influence the stability of microemulsions and provide a new nanoplatform for the delivery of bioactive substances.

EXPERIMENTS

A selenium-containing diol (3,3'-selenobis(propan-1-ol), PSeP) was designed and used as a co-surfactant in a microemulsion with ethoxylated hydrogenated castor oil (HCO40), diethylene glycol monohexyl ether (DGME), 2-n-octyl-1-dodecanol (ODD) and water. The redox-induced transition in PSeP was characterized by ¹H NMR, ⁷⁷Se NMR, and MS. The redox-responsiveness of the ODD/HCO40/DGME/PSeP/water microemulsion was investigated through determination of a pseudo-ternary phase diagram, analysis by dynamic light scattering, and electrical conductivity, and its encapsulation performance was evaluated by determination of the solubility, stability, antioxidant activity, and skin penetrability of encapsulated curcumin.

FINDINGS

The redox conversion of PSeP enabled efficient switching of ODD/HCO40/DGME/PSeP/water microemulsions. Addition of oxidant (H₂O₂), oxidized PSeP into more hydrophilic PSeP-Ox (selenoxide), disrupting the emulsifying capacity of the combination of HCO40/DGME/PSeP, markedly reducing the monophasic microemulsion region in the phase diagram, and inducing phase separation in some formulations. Addition of reductant (N₂H₄·H₂O), reduced PSeP-Ox and restored the emulsifying capacity of the combination of HCO40/DGME/PSeP. In addition, PSeP-based microemulsions can significantly enhance the solubility in oil (by 23 times), stability, antioxidant capacity (DPPH∙ radical scavenging by 91.74 %), and skin penetrability of curcumin, showing clear potential for encapsulation and delivery of curcumin and other bioactive substances.

Emulgels: Promising Carrier Systems for Food Ingredients and Drugs

Novel delivery systems for cosmetics, drugs, and food ingredients are of great scientific and industrial interest due to their ability to incorporate and protect active substances, thus improving their selectivity, bioavailability, and efficacy. Emulgels are emerging carrier systems that represent a mixture of emulsion and gel, which are particularly significant for the delivery of hydrophobic substances. However, the proper selection of main constituents determines the stability and efficacy of emulgels. Emulgels are dual-controlled release systems, where the oil phase is utilized as a carrier for hydrophobic substances and it determines the occlusive and sensory properties of the product. The emulsifiers are used to promote emulsification during production and to ensure emulsion stability. The choice of emulsifying agents is based on their capacity to emulsify, their toxicity, and their route of administration. Generally, gelling agents are used to increase the consistency of formulation and improve sensory properties by making these systems thixotropic. The gelling agents also impact the release of active substances from the formulation and stability of the system. Therefore, the aim of this review is to gain new insights into emulgel formulations, including the components selection, methods of preparation, and characterization, which are based on recent advances in research studies.

Review of the application of surfactants in microemulsion systems for remediation of petroleum contaminated soil and sediments

Microemulsions are important for soil and sediment remediation technology. The characteristics of the surfactants that make up these microemulsions include low sorption into soil or sediments, low surface and interfacial tension, the ability to penetrate tiny pores, and good solubilization of contaminants. This review revealed that microemulsions formulated with nonionic and anionic surfactants have higher recovery efficiencies for hydrophobic contaminants than cationic ones, as evidenced by the surveyed studies reporting effective remediation of soils and sediments using on microemulsions. These microemulsified systems have been found to remove petroleum and its derivatives from soil or sediments at percentages ranging from 40 to 100%. As such, this review can aid with the choice of surfactants used in microemulsions for remediation, such as those with plant-based components, which are promising solutions for the remediation of contaminated soils due to their contaminant extraction efficiency and biodegradability.

Interfacial solute flux promotes emulsification at the water|oil interface

Emulsions are critical across a broad spectrum of industries. Unfortunately, emulsification requires a significant driving force for droplet dispersion. Here, we demonstrate a mechanism of spontaneous droplet formation (emulsification), where the interfacial solute flux promotes droplet formation at the liquid-liquid interface when a phase transfer agent is present. We have termed this phenomenon fluxification. For example, when HAuCl₄ is dissolved in an aqueous phase and [NBu₄][ClO₄] is dissolved in an oil phase, emulsion droplets (both water-in-oil and oil-in-water) can be observed at the interface for various oil phases (1,2-dichloroethane, dichloromethane, chloroform, and nitrobenzene). Emulsification occurs when AuCl₄^- interacts with NBu₄⁺, a well-known phase-transfer agent, and transfers into the oil phase while ClO₄^- transfers into the aqueous phase to maintain electroneutrality. The phase transfer of SCN^- and Fe(CN)₆^3- also produce droplets. We propose a microscopic mechanism of droplet formation and discuss design principles by tuning experimental parameters.

Modifying the Properties of Microemulsion Droplets by Addition of Thermoresponsive BAB* Copolymers

Oil-in-water (O/W) microemulsions (ME) typically feature a low viscosity and exhibit ordinary viscosity reduction as a function of temperature. However, for certain applications, avoiding or even reverting the temperature trend might be required. This can be conceived by adding thermoresponsive (TR) block copolymers that induce network formation as the temperature increases. Accordingly, various ME-polymer mixtures were studied for which three different block copolymer architectures of BAB*-, B₂AB*-, and B(AB*)₂-types were employed. Here, "B" represents a permanently hydrophobic, "A" a permanently hydrophilic, and "B*" a TR block. For the TR-block, three different poly(acrylamide)s, namely poly(N-n-propylacrylamide) (pNPAm), poly(N,N-diethylacrylamide) (pDEAm), and poly(N-isopropylacrylamide) (pNiPAm), were used, which all exhibit a lower critical solution temperature. For a well-selected ME concentration, these block copolymers lead to a viscosity enhancement with increasing temperature. At a polymer concentration of about 22 g L^-1, the most pronounced enhancement was observed for the pNPAm-based systems with factors up to 3, 5, and 8 for BAB*, B₂AB*, and B(AB*)₂, respectively. This phenomenon is caused by the formation of a transitory network mediated by TR-blocks, as evidenced by the direct correlation between the attraction strength and the viscosity enhancement. For applications requiring a high hydrophobic payload, which is attained via ME droplets, this kind of tailored temperature-dependent viscosity control of surfactant systems should therefore be advantageous.

A methodology for measuring the characteristic curvature of technical-grade ethoxylated nonionic surfactants: the effects of concentration and dilution

Characterization of the behaviour of commercially available non-ionic surfactants has received considerable attention due to their efficacy in a variety of applications. The main challenge in the application of these types of surfactants is that the hydrophilicity of the surfactant varies with concentration and dilution due to the polydispersity of the ethylene oxide groups. The hydrophilicity of a surfactant can be quantified by the characteristic curvature (Cc) parameter of the hydrophilic–lipophilic difference (HLD) framework. In this work, a model based on natural logarithmic regression was developed to calculate the Cc value of commercial surfactants as a function of surfactant concentration by a fast and simple phase scan. The slope of the Cc curve and the measured Cc at a reference concentration were used to develop the model. The Cc values determined with the model agreed with the measured values from the phase scans. Furthermore, the linear mixing rule proved to be reliable for mixtures of polydisperse ethoxylated surfactants. Finally, the impact of the water-to-oil ratio on the Cc was evaluated and the implications were discussed.

Swollen cubic phases with reduced hardness solubilizing a model fragrance oil as a co-surfactant

Swollen cubic lyotropic ternary phases with Pn3m symmetry and reduced hardness were obtained from a specific binary mixture of cubic phase-forming (phytantriol) and lamellar phase-forming (decaglycerol monooleate) compounds. The microstructures were determined by using a small-angle x-ray scattering technique. The softness and temperature-induced phase transitions were investigated by means of rheology. The incorporation of a surface-active fragrance compound (linalool) at concentrations up to 6 wt. % induced a structural transition toward a softer Im3m bulk cubic phase with longer water channels. Higher linalool concentrations allowed for the spontaneous dispersion of the bulk cubic phase into microscopic particles with a cubic structure (cubosomes).

Polyelectrolyte-Surfactant Complexes As a Formulation Tool for Drug Delivery

Aqueous polyelectrolyte-surfactant complexes (PESCs) are very rich with respect to their properties and the structures formed by them. By design they normally contain hydrophobic micellar surfactant aggregates complexed by long polyelectrolyte chains, thereby combining the formation of small hydrophobic domains given by the surfactant with large-scale structuring due to the presence of the polyelectrolyte chain. In addition, they contain highly polar regions of surfactant head groups in contact with polyelectrolyte, forming a shell around the micellar aggregates, which often also possesses a certain hydrophobic character. Accordingly, the ability for solubilization of water-insoluble compounds of different sorts is particularly versatile in PESCs. Their solubilization sites with very different polarities and hydrophobic characters make them very flexible in adapting to the requirements of a given drug molecule. This renders them attractive for potential applications in drug delivery. In addition, modification of the rheological properties via self-assembly and network formation can be very important in PESC applications. In the following, we discuss the structures of PESCs and their properties, with a focus on the solubilization properties. Subsequently, examples are described where PESCs have been employed in the context of drug solubilization and delivery. These comprise examples with individual aggregates, cross-linked hydrogels, and ones taking advantage of the high solubilization capacity of microemulsions.

Supramolecular Tools to Improve Wound Healing and Antioxidant Properties of Abietic Acid: Biocompatible Microemulsions and Emulgels

Abietic acid, a naturally occurring fir resin compound, that exhibits anti-inflammatory and wound-healing properties, was formulated into biocompatible emulgels based on stable microemulsions with the addition of a carbamate-containing surfactant and Carbopol^® 940 gel. Various microemulsion and emulgel formulations were tested for antioxidant and wound-healing properties. The chemiluminescence method has shown that all compositions containing abietic acid have a high antioxidant activity. Using Strat-M^® skin-modelling membrane, it was found out that emulgels significantly prolong the release of abietic acid. On Wistar rats, it was shown that microemulsions and emulgels containing 0.5% wt. of abietic acid promote the rapid healing of an incised wound and twofold tissue reinforcement compared to the untreated group, as documented by tensiometric wound suture-rupture assay. The high healing-efficiency is associated with a combination of antibacterial activity of the formulation components and the anti-inflammatory action of abietic acid.

Molecular Mapping of Antifungal Mechanisms Accessing Biomaterials and New Agents to Target Oral Candidiasis

Oral candidiasis has a high rate of development, especially in immunocompromised patients. Immunosuppressive and cytotoxic therapies in hospitalized HIV and cancer patients are known to induce the poor management of adverse reactions, where local and systemic candidiasis become highly resistant to conventional antifungal therapy. The development of oral candidiasis is triggered by several mechanisms that determine oral epithelium imbalances, resulting in poor local defense and a delayed immune system response. As a result, pathogenic fungi colonies disseminate and form resistant biofilms, promoting serious challenges in initiating a proper therapeutic protocol. Hence, this study of the literature aimed to discuss possibilities and new trends through antifungal therapy for buccal drug administration. A large number of studies explored the antifungal activity of new agents or synergic components that may enhance the effect of classic drugs. It was of significant interest to find connections between smart biomaterials and their activity, to find molecular responses and mechanisms that can conquer the multidrug resistance of fungi strains, and to transpose them into a molecular map. Overall, attention is focused on the nanocolloids domain, nanoparticles, nanocomposite synthesis, and the design of polymeric platforms to satisfy sustained antifungal activity and high biocompatibility with the oral mucosa.

A Poly (Caprolactone)-Cellulose Nanocomposite Hydrogel for Transdermal Delivery of Hydrocortisone in Treating Psoriasis Vulgaris

Psoriasis vulgaris (PV) is a common chronic disease, affecting much of the population. Hydrocortisone (HCT) is currently utilized as a PV treatment; however, it is associated with undesirable side effects. The aim of this research was to create a thermo-responsive nano-hydrogel delivery system. HCT-loaded sorbitan monostearate (SMS)-polycaprolactone (PCL) nanoparticles, encapsulated with thermo-responsive hydrogel carboxymethyl cellulose (CMC), were synthesized by applying the interfacial polymer-deposition method following solvent displacement. The nanoparticles’ properties were evaluated employing Differential Scanning Colorimetry, Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Zeta sizer, Ultraviolet/Visual spectroscopy, and cytotoxicity testing. The nanoparticle sizes were 110.5 nm, with polydispersity index of 0.15 and zeta potential of −58.7 mV. A drug-entrapment efficacy of 76% was attained by the HCT-loaded SMS-PCL nanoparticles and in vitro drug-release profiles showed continuous drug release over a period of 24 hrs. Keratinocyte skin cells were treated with HCT-loaded SMS-PCL nanoparticles encapsulated with CMC; the results indicated that the synthesized drug-delivery system was less toxic to the keratinocyte cells compared to HCT. The combined trials and results from the formulation of HCT-loaded SMS-PCL nanoparticles encapsulated with CMC showed evidence that this hydrogel can be utilized as a potentially invaluable formulation for transdermal drug delivery of HCT, with improved efficacy and patient conformity.

Short-chain branched sulfosuccinate as a missing link between surfactants and hydrotropes

Surfactants aggregate in water into micelles, and these micelles incorporate organic substances to solubilize them. Hydrotropes are compounds that increase the solubility of hydrophobic substances in water without this form of aggregation. Decreasing the chain length of the classical surfactant Aerosol OT (AOT) from C8 to C5 results in a molecule with intermediate properties. Molecular dynamics simulations and surface tension measurements are performed on this short chain derivative of AOT. This compound shows high solubility and at the same time progressive weak aggregation. The hydration of head groups hinders significant plunging into a hydrophobic core, which leads to well defined liquid chain nanodomains. The transition to bicontinuous aggregates is in the concentration range of 1 mol L^-1. The sulfonate group of the head groups (placed at the water interface of worm-like aggregates) rather than the aggregate-aggregate interaction is responsible for the unusual small angle X-ray scattering pattern.

Thermoresponsive Self-Assembly of Twofold Fluorescently Labeled Block Copolymers in Aqueous Solution and Microemulsions

A nonionic double hydrophilic block copolymer with a long permanently hydrophilic and a small thermoresponsive block is synthesized by reversible addition-fragmentation chain-transfer polymerization (RAFT). By employing a specifically designed chain-transfer agent, the polymer is functionalized with complementary end groups which are suited for Förster resonance energy transfer (FRET). The end group attached to the permanently hydrophilic block of poly(N,N-dimethylacrylamide) pDMAm is designed as a permanently hydrophobic segment ("sticker") comprising a long alkyl chain and the 4-aminonaphthalimide fluorophore. The other end attached to the thermoresponsive block of poly(N-isopropylacrylamide) pNiPAm incorporates a coumarin fluorophore. The temperature-dependent self-assembly of the twofold fluorescently labeled copolymer is studied in pure aqueous solution as well as in an o/w microemulsion by several techniques including turbidimetry, dynamic light scattering (DLS), and fluorescence spectroscopy. It is compared to the behaviors of the analogous twofold-labeled pDMAm and pNiPAm homopolymer references. The findings indicate that the block copolymer behaves as a polymeric surfactant at low temperatures, with one relatively small hydrophobic end block and an extended hydrophilic chain forming "hairy micelles". At elevated temperatures above the LCST phase transition of the pNiPAm block, however, the copolymer behaves as an associative telechelic polymer with two nonsymmetrical hydrophobic end blocks, which do not mix. Thus, instead of a network of bridged "flower micelles", large dynamic aggregates are formed. These are connected alternatingly by the original micellar cores as well as by clusters of the collapsed pNiPAm blocks. This type of structure is even more favored in the o/w microemulsion than in pure aqueous solution, as the microemulsion droplets constitute an attractive anchoring point for the hydrophobic dodecyl sticker but not for the collapsed pNiPAm chains.

In Situ Dielectric Spectroscopy Monitoring of Silica Nanoparticle Synthesis in Cationic Water-in-Oil Microemulsions

In situ monitoring of microemulsion-based nanoparticle synthesis is significant for understanding the particle formation mechanism and for advancing controlled nanoparticle synthesis by this means. In this study, the processes of silica nanoparticle synthesis in a CTAB/n-hexanol/cyclohexane/ammonia microemulsion were monitored via dielectric spectroscopy in situ and in real time, with the influences of the water content and precursor concentration being considered. Two dielectric relaxations in addition to a water-induced one were observed in the frequency range of 1 MHz to 3 GHz, which persist throughout the synthesis processes. It is suggested that the lower-frequency relaxation is ascribed to interfacial polarization and the higher-frequency one is caused by the orientational polarization of the ion pair consisting of a counterion and a surfactant polar group. The latter and water-induced relaxations were found to be barely changed during the synthesis processes, while the former changes obviously with synthesis time. The evolution of the lower-frequency relaxation and direct current conductivity with synthesis time are presented and discussed, on the basis of which the particle formation process is inspected from a dielectric spectroscopic point of view.

Surface Properties of Alkyldi(oxyethylene) β-D-Maltoside

A series of nonionic disaccharide-based surfactants alkyldi(oxyethylene) β-d-maltosides (4a-4h, n = 6-16) were synthesized, and their physicochemical properties were further investigated. Six β-D-maltosides (4c-4h, n = 8-16) exhibited a fan-shaped texture feature, whereas hexyldi(oxyethylene) β-D-maltoside (4a) had the strongest hygroscopicity. Owing to the incorporation of the hydrophilic dioxyethyl spacer (-(OCH₂CH₂)₂-), the related water solubility improved significantly. Tetradecyldi(oxyethylene) β-D-maltoside (4g) had good water solubility, whereas hexadecyldi(oxyethylene) β-D-maltoside (4h) had weak water solubility. Meanwhile, the surface tension of β-D-maltosides (4a-4g, n = 6-14) had a decreasing tendency with increasing the alkyl chain length, whereas 4g had the best surface activity. Furthermore, decyldi(oxyethylene) β-D-maltoside (4e) had the best foaming ability and foam stability. Dodecyldi(oxyethylene) β-D-maltoside (4f) had the best emulsifying property in the rapeseed oil/water system. In contrast, both ammonium dodecyl sulfate (NH₄DS)/4f and cetyltrimethylammonium chloride (CTAC)/4f binary surfactant systems showed a synergistic effect in surface activity because the C_CMC/CMC^id_mix was <1. NaCl impacted the surface activity of the aqueous 4f solution through salt-surfactant synergistic effects. The results showed that such surfactants should have potential applications in the related field in the future.

Extraction Induced by Emulsion and Microemulsion Breaking for Metal Determination by Spectrometric Methods - A Review

This review focuses on extraction induced by the destabilization of emulsified systems combined with spectrometric techniques for metal analysis in oily samples. This approach is based on the formation and breaking of an emulsion (extraction induced by emulsion breaking - EIEB) or microemulsion (extraction induced by microemulsion breaking - EIMB) to transfer the analytes from the oil sample to the aqueous phase, which is separated in the process. Its simplicity, speed, and low cost have contributed to its growing popularity among researchers. However, the potential of EIEB and EIMB is far from being fully exploited. Therefore, this paper aims to provide relevant information to expand the applicability of these methods. The principle of the methods is discussed, and a brief description of emulsified systems is presented. The parameters affecting the extraction efficiency and calibration strategy are also critically discussed. Furthermore, the analytical applications of the methods are reviewed. Trends and opportunities in this field are also considered.

Mn doped Prussian blue nanoparticles for T1/T2 MR imaging, PA imaging and Fenton reaction enhanced mild temperature photothermal therapy of tumor

BACKGROUND

Combining the multimodal imaging and synergistic treatment in one platform can enhance the therapeutic efficacy and diagnosis accuracy.

RESULTS

In this contribution, innovative Mn-doped Prussian blue nanoparticles (MnPB NPs) were prepared via microemulsion method. MnPB NPs demonstrated excellent T1 and T2 weighted magnetic resonance imaging (MRI) enhancement in vitro and in vivo. The robust absorbance in the near infrared range of MnPB NPs provides high antitumor efficacy for photothermal therapy (PTT) and photoacoustics imaging property. Moreover, with the doping of Mn, MnPB NPs exhibited excellent Fenton reaction activity for chemodynamic therapy (CDT). The favorable trimodal imaging and Fenton reaction enhanced mild temperature photothermal therapy in vitro and in vivo were further confirmed that MnPB NPs have significant positive effectiveness for integration of diagnosis and treatment tumor.

CONCLUSIONS

Overall, this Mn doped Prussian blue nanoplatform with multimodal imaging and chemodynamic/mild temperature photothermal co-therapy provides a reliable tool for tumor treatment.

Tanshinone IIA Microemulsion Protects against Cerebral Ischemia Reperfusion Injury via Regulating H3K18ac and H4K8ac In Vivo and In Vitro

Tanshinone IIA (TanIIA) has neuroprotective effects against cerebral ischemia reperfusion injury (CIRI), but its clinical application is limited due to poor water solubility and robust first pass elimination property. In this study, we developed microemulsion loaded with TanIIA (TanIIA ME) to break through these limitations, and explored the neuroprotective effect of TanIIA ME against CIRI and the epigenetic regulation mechanism of this neuroprotection. In vivo, middle cerebral artery occlusion (MCAO) models were treated with TanIIA ME and TanIIA solution or sodium valproate as a control. The effect of TanIIA ME on HDAC activity was determined by ELISA assay. In addition, we used primary hippocampal neurons to establish oxygen-glucose deprivation and reoxygenation (OGD/R) models. Lactate dehydrogenase (LDH) assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed to investigate the neuroprotective efficacy of TanIIA ME. Subsequently, the expression of H3K18ac, H4K8ac, NMDAR1, caspase-3, and MAP-2 were investigated in MCAO or OGD/R models treated with TanIIA ME, TanIIA solution or sodium valproate. In vivo experimental results indicated that TanIIA ME significantly reduced neurological scores, infarction volume, and HDAC activity compared with TanIIA solution and MCAO group, accompanied by upregulation of H3K18ac, H4K8ac, and MAP-2 expression and downregulation of NMDAR1 and caspase-3 expression. Additionally, in OGD/R models, the results demonstrated that TanIIA ME treatment had a better neuroprotective effect along with increased H3K18ac, H4K8ac, and MAP-2 expression and decreased NMDAR1 and caspase-3 expression, compared with the other treatments except sodium valproate. Overall, TanIIA ME treatment exhibited superior efficacy in protecting against CIRI through mechanisms that might involve the inhibition of NMDAR1 and caspase-3 expression and the enhancement of MAP-2 expression by regulating histone H3K18 and H4K8 acetylation. Thus, TanIIA ME could be potentially used to develop a promising drug for the treatment of ischemic stroke.

High-resolution structural elucidation of extremely swollen lyotropic phases

Self-assembled lyotropic phases are important in a variety of applications, in particular microemulsions are essential for formulation science. A spectacular situation arises when microemulsions are made to swell by systematically increasing the bending modulus of the surfactant film separating the oil and water regions. In an attempt to realize such extremely swollen microemulsion phases, Peter et al. [Phys. Rev. Lett., 76 (1996) 3866] found a variety of lyotropic phases including a long-range ordered three-dimensional cubic phase over a narrow section of the complex phase diagram of a pseudo-quaternary system composed of decane, brine, octanol, and sodium dodecyl sulfate. In this work, the same region of the phase diagram was reinvestigated using high-resolution small-angle X-ray scattering (HR-SAXS) and rheo-SAXS, which is an important technical aspect for homogenizing the sample and orienting the structural units. Whilst the formation of a swollen two-dimensional hexagonal phase was observed, the structural features of a cubic phase were not detected. The long correlation lengths noted prior were also seen here, over 2000 nm for the hexagonal phase, taken from rheo-SAXS measurements. Based on the measurements covering more than three orders of magnitude in scattering vector, the structure appeared to be an organization of elongated swollen emulsion droplets, which could form an interconnected structure, dense liquid-like order, or further order into a hexagonal morphology with unusually large lattice spacings for a surfactant system.