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A novel sanitizer tablet containing clove essential oil (CO) microemulsion was developed. A preformulation study using nuclear magnetic resonance and thermal analyses showed component compatibility. The main components of the samples remained intact despite a color change, probably due to a strong acid-base interaction between eugenol and diethanolamine. The CO microemulsion showed acaricidal and larvicidal activities superior to the commercial product, with product efficacy of 99.9% and larvae mortality of 94%. Optimal spray-drying conditions were achieved with inlet and outlet temperatures of 50°C and 40°C, respectively, an aspiration rate of 1 m3 min⁻1, and a 0.25 L h⁻1 injection flow. The feed suspension comprised 50% (v/v) liquid soap, 37.5% (v/v) water, 12.5% (v/v) ethanol, and 5.0% (w/v) silica. This formulation and processing parameters allowed for successful free-flow powder formation, providing a suitable matrix for incorporating the CO microemulsion via wet granulation without heating. Finally, sanitizer tablets produced from such granules resulted in a uniform product with low weight variation (coefficient of variation of 0.15%), eugenol content of 95.5% ± 3.3, and friability of 0.58%. Furthermore, the tablets showed rapid aqueous dispersion, forming a colloidal system with particle sizes of 221 nm and a zeta potential of -17.2 mV. Antimicrobial activity tests demonstrated the effectiveness of the sanitizer tablet against bacteria and fungi, exhibiting comparable antimicrobial potency to isolated CO. Hence, the sanitizer tablet developed represents a promising candidate as a practical and efficient solution for pest control, offering strong antimicrobial and acaricidal activity. [ABSTRACT FROM AUTHOR]

In this research work, a new biocompatible microemulsion containing castor oil has been formulated to increase the solubility of celecoxib, as a well-known anti-inflammatory drug. In this formulation castor oil has also anti-inflammatory properties. The proposed oil-in-water microemulsion composed of Tween 80 as surfactant, isobutanol as co-surfactant, and castor oil as the oil phase. In the first step, the phase diagrams of the proposed colloid systems with surfactant to co-surfactant mass ratios of 4 : 1 and 2 : 1 were prepared at ambient temperature. Then, using the obtained phase diagrams, the appropriate formulations were selected by combining different percentages of water, oil, surfactant and co-surfactant in the microemulsion region. Some of physico-chemical properties, such as electrical conductivity, density, refractive index, surface tension and particle size of the selected microemulsion formulations have been determined at 298 K. After that, the solubility of celecoxib in the selected formulations was determined and compared with other reported microemulsion formulations. Interesting results from this section indicated that the solubility of celecoxib significantly increased compared to pure water and the previous proposed formulations. The results of this study can be used to provide suitable formulations based on the biocompatible microemulsions for celecoxib in pharmaceutical industry. [ABSTRACT FROM AUTHOR]

The interest towards microemulsions and nanoemulsions, the colloidal systems utilized to encapsulate bioactive compounds, is constantly increasing in food industries. Major characteristics of microemulsions and nanoemulsions should be assessed to better differentiate these two systems. Limitations and restrictions being imposed on the development of food-grade microemulsions and nanoemulsions should be addressed to improve their significant role in the food and beverage industry. Food studies should consider practical issues more thoroughly and apply effective inexpensive measures to minimize surfactant losses and improve surfactant recovery to bridge the gap between laboratory experiments and industrial processes. [ABSTRACT FROM AUTHOR]

Cultural heritage assets constitute a fundamental socioeconomic resource, but the actual works of art need to be maintained, counteracting degradation processes, to transfer these benefits to future generations. In particular, the removal of soil, aged coatings, and vandalism/overpaints is one of the most needed interventions in art restoration. Traditional cleaning methodologies, based on classical solution and polymer chemistry, only grant limited control of the cleaning interventions, with the risk of affecting the original components of the artifacts, and often involving the use of toxic or non-environmentally friendly compounds. Alternatively, materials science, colloids, and soft matter have provided valuable and safe solutions in the last decades. This review provides a selection of the most recent and advanced methodologies for the wet cleaning of works of art, spanning from nanostructured cleaning fluids (microemulsions, surfactants swollen micelles) to physical and chemical gels. The new methodologies work on different physico-chemical mechanisms, such as processes for detaching/dewetting, to selectively remove the unwanted layers in sustainable and cost-effective interventions. The best performing systems, like microemulsions confined in "twin-chain" polyvinyl alcohol gels, have been assessed in the cleaning of masterpieces such as works by Pablo Picasso, Jackson Pollock and Roy Lichtenstein. Particular attention is dedicated to "green" chemistry systems, using low-toxicity solvents or bio-based/waste materials to build gel networks. Finally, current trends and future perspectives are given, showing that advanced systems for art cleaning link with transversal fields of crucial importance even beyond Cultural heritage conservation, e.g., detergency, tissue engineering, drug-delivery, food industry and cosmetics. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Curcumin is the principal curcuminoid found in the rhizomes of turmeric. Due to its therapeutic action against cancer, depression, diabetes, some bacteria, and oxidative stress, it has been used widely in medicine since ancient times. Due to its low solubility, the human organism cannot completely absorb it. Advanced extraction technologies, followed by encapsulation in microemulsion and nanoemulsion systems, are currently being used to improve bioavailability. This review discusses the different methods available for curcumin extraction from plant material, methods for the identification of curcumin in the resulting extracts, its beneficial effects on human health, and the encapsulation techniques into small colloidal systems that have been used over the past decade to deliver this compound. [ABSTRACT FROM AUTHOR]

Skin inflammation is a symptom of many skin diseases, such as eczema, psoriasis, and dermatitis, which cause rashes, redness, heat, or blistering. The use of natural products with anti-inflammatory properties has gained importance in treating these symptoms. Ursolic acid (UA), a promising natural compound that is used to treat skin diseases, exhibits low aqueous solubility, resulting in poor absorption and low bioavailability. Designing topical formulations focuses on providing adequate delivery via application to the skin surface. The aim of this study was to formulate and characterize lipid-surfactant-based systems for the delivery of UA. Microemulsions and liquid crystalline systems (LCs) were characterized by polarized light microscopy (PLM), rheology techniques, and textural and bioadhesive assays. PLM supported the self-assembly of these systems and elucidated their formation. Rheologic examination revealed pseudoplastic and thixotropic behavior appropriate, and assays confirmed the ability of these formulations to adhere to the skin. In vivo studies were performed, and inflammation induced by croton oil was assessed for response to microemulsions and LCs. UA anti-inflammatory activities of ~60% and 50% were demonstrated by two microemulsions and 40% and 35% by two LCs, respectively. These data support the continued development of colloidal systems to deliver UA to ameliorate skin inflammation. [ABSTRACT FROM AUTHOR]

Nanoparticle interactions can mediate assemblies and self‐organization into colloidal superstructures, if then control of the size and stabilization is highly required towards the fabrication of functional nanomaterials. In the proposed approach, different types of water‐dispersible and oil‐dispersible nanoparticles were incorporated in water‐in oil (w/o) microemulsions stabilized by Aerosol‐OT (AOT) as surfactant. Phase separation at higher surfactant and water contents resulted in the formation of a heterocoagulate, which can be separated with an external magnet. This magnetic heterocoagulate, which can contain 3 different types of nanoparticles, can be dispersed in longer‐chain carboxylic acids. An additional phase‐transfer into oil‐in water (o/w) dispersions was mediated by an auxiliary surfactant in water‐ethanol. The resulting nanostructures from heterocoagulates formed at higher temperatures consisted on inner domains of water‐dispersible nanoparticles embedded in a matrix‐shell of oleyl‐capped nanoparticles. Thus, a new encapsulation strategy is achieved under relative mild conditions, combining three types of nanoparticles and providing compartmentalization and magnetic‐responsiveness. [ABSTRACT FROM AUTHOR]

Pham-Van et al. [[1]] numerically simulated the self-assembly of 2D clusters of colloidal particles assisted by the evaporation of an emulsion stabilized by nanoparticles (Pickering emulsions). Depending on the components' proportions, the microstructure of microemulsions ranges from tiny water droplets dispersed in the oil phase (W/O microemulsion) to oil droplets dispersed in the aqueous phase (O/W microemulsions). Microemulsions are known as thermodynamically stable nanodispersions driven by spontaneous emulsification and are commonly prepared as transparent mixtures composed of oil, water, a surfactant, and a cosurfactant. [Extracted from the article]

[Display omitted] • Lemon oil composition impacts surface activity and oil loading. • Type and content of co-solvent are fundamental for microemulsion formation. • Interactions between aqueous and oil phases are observed. • Compatibility-based development of dilutable clear emulsions is feasible. 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. [ABSTRACT FROM AUTHOR]

This document is an editorial published in Frontiers in Materials on March 25, 2024. The editorial, titled "2022 Retrospective: Colloidal Materials and Interfaces," highlights the diverse research undertaken in the field of colloidal science. The editorial discusses five distinct papers that cover a wide range of applications, including photocatalytic degradation of pollutants, enhanced drug delivery systems, reservoir rock dynamics, nanocellulose properties, and ophthalmic drug delivery. The editorial expresses appreciation to the authors and reviewers for their contributions and looks forward to future breakthroughs in the field of colloidal materials and interfaces. [Extracted from the article]

We describe here a method to synthesize ultrasmall nanocapsules with a diameter of 6 nm, exhibiting a well‐defined core–shell morphology. Remarkably, the nanocapules are synthesized in a miniemulsion process without the need of large amounts of surfactant as commonly used in the microemulsion process. Ultrasmall nanocapsules with an oil core and a silica shell are formed by the concurrent processes of a sol–gel reaction and Ostwald ripening. Using solvents with different water solubilities and alkoxysilanes with different reactivities, we demonstrate that sizes of obtained nanocapsules depend on the ripening rate and alkoxysilane conversion rate. The method can be also used for encapsulating natural oils such as peppermint oil and limonene. This work shows that the Ostwald ripening phenomenon can be employed beneficially for the preparation of very small colloids. [ABSTRACT FROM AUTHOR]

Colloid science is contributing solutions to counteract the degradation of artifacts, favoring their transfer to future generations. Advanced materials such as nanoparticles, coatings, gels and microemulsions have been assessed in conservation, spanning from archeological sites to modern and contemporary art. We give an overview of the fundamental milestones and latest innovations in conservation science, targeting solutions and tools for remedial conservation based on green nanomaterials and hybrid systems. Future perspectives and outstanding challenges in this exciting field are then outlined. [ABSTRACT FROM AUTHOR]

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Fluid-like colloidal structures are key components in nature's own functional materials and important for various applications. For instance, self-assembled structures are formed spontaneously by amphiphilic molecules in solvent, tailored by directional noncovalent intermolecular forces. These structures form the framework of cells defining their geometry and microenvironments for chemical reactions, for maintaining concentration gradients, and for nutrient exchange. Knowledge on the mechanisms at play that underlie the self-assembly of amphiphilic molecules into nanostructures in aqueous and nonaqueous solvents and their dispersion into particles can have direct implications for the rational design of new advanced and nature-inspired materials. These colloidal materials could help to deliver drug molecules and nutrients in a tailored manner to the body, or act as sustainable solvents for chemical or biotechnological processes. This contribution summarizes the recent progress in understanding the self-assembly structure formation in polar and nonpolar solvents and discusses the advances in hierarchically organized systems. Furthermore, it discusses challenges in the characterization of structure and dynamics in these biomimetic materials and highlights selected applications in the fields of drug delivery, food, and biotechnology. Image 1 [ABSTRACT FROM AUTHOR]

Transcutol® is a perfect solubilizer and an effective permeation enhancer of many active substances commonly used in cosmetics. Microemulsions due to the content of surfactant and co-surfactant could be also considered as chemical permeation enhancers that may support transdermal delivery of poorly water- soluble drugs. The purpose of this study was to investigate the effect of Transcutol® and potential microemulsions on diffusion of poorly soluble indomethacin through an artificial membrane and excised rat skin. After drug solubilization in different enhancers, drug was dispersed in sodium alginate or carbopol gel used as dermal basis. For characterization of the microemulsions, the basic physico-chemical properties were determined. In vitro as well as ex vivo drug release was determined by vertical Franz cells. Enhancing effect of the examined microemulsions was observed only in carbopol gel. There was an increase in cumulative drug amount released through synthetic membrane by 37.7–39.8% from the microemulsion formulation and 90.6% from Transcutol® formulation within 6 h compared to the control samples. The differences between the permeation curves with or without the content of the enhancers were statistically significant (p <.05). Pearson correlation coefficients indicate a very high degree of dependence (r > 0.9) between in vitro and ex vivo drug release from all dermal vehicles used. It can be stated that Transcutol® is the best solubilizer and also penetration enhancer from the examined, and therefore it seems to be effective excipient/solubilizer in topical IND formulation. [ABSTRACT FROM AUTHOR]

Objectives: Sulconazole is a broad spectrum antifungal agent of the imidazole class used against dermatophytes and other fungi to treat skin infections. The aim of the present work was to formulate and evaluate a microemulsion-based topical sulconazole gel. Materials and Methods: Microemulsion formulation of sulconazole nitrate was prepared by using oil, surfactant, cosurfactant and water at different ratios. This was then subjected to clarity and particle size analysis, a centrifugation test, a dilution test, and freeze thawing. Results: The zeta potential of formulation F1 was -41.3 and stable. The pH of the microemulsion formulation was within the range of pH of skin. F1 showed a higher percentage amount of drug as compared with the other formulations. The viscosity showed that F1 was optimum. The freezing and thawing results showed there was no phase separation and the formulation was stable. In vitro drug release showed that the drug release from the microemulsion of F1 was higher when compared to the other formulations. It revealed F1 had the highest drug content of 95.88±0.3% and % cumulative drug release was 88.75% release in 8 h. The in vivo skin irritation study on rats confirmed that formulation was nontoxic and nonirritant. Conclusion: The present study confirmed the safety of the formulated sulconazole loaded microemulsion gel for topical application. [ABSTRACT FROM AUTHOR]

Introduction: Drug delivery through topical route is mostly preferred for local dermatological action. Topical action of preparations has certain limitations in terms of drug solubility, residence time, lipophilicity and permeability. Conventional dosage forms such as creams, ointments etc exhibit drawbacks like problem in stability, stickiness, poor absorption as well as permeation mainly in case of large molecule. To overcome this, the origination of emulgel came into existence which basically focus on the delivery of hydrophobic drugs.1 The present research is proposed to prepare and evaluate microemulsion based luliconazole gel for its enhanced solubility and permeability for better antifungal activity. Materials and Methods: The present study was aimed to prepare and evaluate microemulgel of luliconazole for topical application by using poly unsaturated fatty acids such as linseed oil. Sodium alginate was used as a gelling agent. Luliconazole microemulsion was prepared by varying the concentration of surfactants while the oil concentration was kept fixed. It was characterized for globule size and physical stability. Microemulgel was prepared and characterized for drug content, viscosity, spreadability, in vitro permeation study, skin irritation test, in vitro antifungal study and stability study. Skin irritation test was carried out after taking approval of Institutional Animal Ethics Committee. Results and Discussion: Two microemulsion were selected based on the globule area, PDI and physical stability and incorporated into the gel base of sodium alginate. The optimized microemulgel (F1) showed acceptable physical properties with lowest viscosity value (2325 cps) and showed pseudoplastic behaviour, highest spreadability value (3.7 gm.cm/sec), Highest drug permeation (63.50%) after 5 hr. Skin irritation test showed no signs of irritation in any rats. Optimized formulation F1 represents greater zone of inhibition (38 mm) as compared to pure gel (34 mm) and showed acceptable stability profile. Conclusion: It can be concluded that luliconazole microemulgel prepared with linseed oil and sodium alginate can be a choice for topical antifungal treatment. [ABSTRACT FROM AUTHOR]

Flurbiprofen (FP) is one of the most potent nonsteroidal anti-inflammatory drugs with very low bioavailability of approximately 12% following transdermal administration, compared to that after oral administration. This study aimed to deliver FP as a microemulsion (ME) gel by transdermal administration. Galangal essential oil (GEO) was extracted from Rhizoma Alpiniae Officinarum and identified by GC-MS. The most abundant constituent was determined to be 1,8-cineole (52.06%). Compared to azone, GEO was proved to exert significantly higher (p <.01) penetration enhancement effect and significantly (p <.001) lower skin cell toxicity. The formulation (FP-GEO-ME gel) was prepared using GEO as an oil phase and a penetration enhancer. Compared to that of FP solution, the enhancement ratio (ER) of FP-GEO-ME gel was 4.06. In addition, more than 25% 1,8-cineole permeated through the rat skin. In vivo pharmacokinetic studies revealed that the AUC0–t of FP after transdermal administration of FP-GEO-ME gel was higher by approximately 4.56-fold than that of marketed FP cataplasms. The relative bioavailability of FP and 1,8-cineole after transdermal administration compared to oral administration of FP-GEO-ME were determined to be 96.58% and 85.49%, respectively. FP-GEO-ME gel significantly inhibited carrageenan-induced hind-paw edema and decreased PGE2 levels in rat serum. GEO-ME gel also exhibited significant anti-inflammatory effects at 2 h after the therapy (p <.05). The synergistic effects of FP and GEO were expected for the application of FP-GEO-ME gel. In conclusion, GEO-ME gel may be a promising formulation for transdermal administration of anti-inflammatory hydrophobic drugs, such as FP. [ABSTRACT FROM AUTHOR]

The present study aims at designing a thermosensitive gel prepared from w1/o/w2 multiple microemulsions (MMEs) for the vaginal delivery of siRNA. The w1/o/w2 MMEs were prepared by two-step emulsifications: the first step was to prepare primary emulsions (w1/o) by low energy emulsification (LEE); the second step was to obtain stable w1/o/w2 MMEs by self-emulsifying. An extensive formulation optimization process was undertaken. The final w1/o/w2 MMEs could be formed in ddH2O, phosphate buffer solution (PBS, pH 7.4) and 1640 culture media with diameter size about 166.5 ± 13.1, 271.0 ± 11.1 and 278.7 ± 12.1 nm respectively. The release rates of siRNA from solutions, MMEs and MMEs-gels were completed within 2 h, 6 h and13 h respectively. The transfection efficiency of MMEs was confirmed both in vitro and in vivo. The relative target gene expressions of MMEs were 0.07 ± 0.05% vs. 0.37 ± 0.06% in Hela cells against Lipofectamine2000® and 1.88% ± 0.00% vs. 9.65% ± 0.02% in mouse vaginal mucosa against PEI. Good biocompatibility of MMEs was verified by cytotoxicity and pathological studies. Overall, our results indicated the potential of the MMEs-gel system for the vaginal delivery of siRNA. [ABSTRACT FROM AUTHOR]

Introduction: Etoricoxib is a poorly water-soluble oral NSAID and is associated with a number of complications such as bleeding, ulcers and dyspepsia but these can be overcome by delivering the drug topically. Objectives: Microemulgel for the topical delivery of etoricoxib was formulated to increase its solubility and thus improve the skin permeability. Methods: The solubility of etoricoxib was studied in various oils, surfactants and cosurfactants. Pseudo-ternary phase diagrams were constructed by varying the surfactant to cosurfactant (Smix) ratio. Microemulsions with different compositions were formulated and optimized. Selected o/w microemulsions contained 1% etoricoxib and were evaluated for pH, rheology, drug content, particle size and in vitro drug release. Optimized microemulsion was incorporated in 1% Carbopol® 934 and was evaluated for rheological properties, spreadability, in vitro permeation, skin irritation and stability. Results: Capryol™ 90, Tween 80 and Transcutol® P exhibited the highest solubility. Maximum microemulsion region was observed when the Smix ratio was 3:1. The average particle size of the optimized microemulsion was 37.61 nm, zeta potential was -2.88 mV and permeability of the drug from the microemulsion was 66.8% after 8 h. The prepared gel showed 57.8% drug release after 8 hr. Skin irritation studies indicated that the optimized formulation was safe for topical application. Stability studies indicated that the formulation remained unaffected at accelerated storage conditions. Conclusion: Results indicated that the micro-emulgel has potential for sustained action of drug release and may act as a promising tool to enhancepercutaneous delivery of etoricoxib. [ABSTRACT FROM AUTHOR]

The application of acoustic spectroscopy to the characterization of binary C12EO7—water system was studied. It was discovered that the size of micelles in aqueous surfactant solutions could not be determined, but it was possible to determine the size of water nanodomains existing in the surfactant‐rich systems. It was suggested that in colloidal systems, the energy of ultrasonic waves is dissipated only by interfaces existing between condensed phases. The characterization of Winsor transitions by acoustic spectroscopy in water/d‐limonene system stabilized by a mixture of nonionic surfactant and isopropyl alcohol (cosolvent) was also explored. In one study, systems with a constant d‐limonene to water weight ratio obtained in the course of titration of d‐limonene‐in‐water emulsion with increasing amounts of surfactant+alcohol were investigated. In another study, a balanced d‐limonene/water microemulsion was sequentially diluted with water and d‐limonene. The transition between Winsor I and Winsor IV systems was monitored in both cases. Droplet size distributions were calculated using different models for dispersed and continuous phase composition. It was demonstrated that the magnitude of acoustic scattering played a significant role in the ability to reliably determine droplet size distributions, and in particular to simultaneously observe nanometer‐size and micron‐size droplets in Winsor I systems. An attempt was made to account for intrinsic attenuation of surfactant and alcohol by associating them with the aqueous phase, but this approach was shown not to be applicable in the case of Winsor IV microemulsions. [ABSTRACT FROM AUTHOR]

Microemulsions were recognized after the work of Hoar and Schulman in 1943, which revealed the use of strong surface-active agent leading to spontaneous emulsification; however, it was in 1959 when Schulman first used the term “microemulsion” for such emulsion system. Microemulsions are optically transparent, thermodynamically stable colloidal systems, 10–100 nm diameters that form spontaneously upon mixing of oil, water, and emulsifier. After its discovery in 1943 to till date, more than 1200 publications have been reported and development of O/W type of microemulsions has been the priority for the researchers, mostly using non-ionic surfactants. Although microemulsions seem to be one of the most promising candidates in pharmaceuticals because of relative ease in the formulation and distinct characteristics when compared to other dispersion systems, its commercial success as a drug delivery system has been very little. Much of the time after its discovery has been exhausted in failure to understand correct formulation requisites or confusing it with other similar systems. In the face of increasing the number of publication year after year, its formulation has been generally based on trial -and-error. Efficient strategies for excipient selection and detailed understanding of microstructures contributing to its formulation is still required which may serve as the foundation for attaining greater success in this field. [ABSTRACT FROM AUTHOR]

Background and objectives: Critically ill patients present reduced endogenous melatonin blood levels, and they might benefit from its exogenous supplementation. The aim of this research was to evaluate the feasibility of different routes of administration and drug formulations of melatonin. The efficiency of absorption was assessed as well as the adequacy in achieving and maintaining the physiological nocturnal blood peak. Methods: Twenty‐one high‐risk critically ill patients were randomly assigned to receive melatonin either: (a) per os, as a standard tablet (ST‐OS), (b) per os, as a suspension in solid lipid nanoparticles (SLN‐OS) or c) transdermal (TD), by applying a jellified melatonin microemulsion (μE) on the skin (μE‐TD). SLN‐OS and μE‐TD were lipid‐based colloidal systems. The endogenous melatonin blood values were observed for 24 hours; subsequently, melatonin 3 mg was administered and pharmacokinetics was studied for 24 hours further. Results: In both groups that received ST‐OS and SLN‐OS, the median time‐to‐peak blood concentration was 0.5 hours; however, the area under the curve (AUC) after administration of SLN‐OS was significantly higher than after ST‐OS (157386 [65732‐193653] vs 44441 [22319‐90705] pg/mL*hours, P = 0.048). μE‐TD presented a delayed time‐to‐peak blood concentration (4 hours), a lower bioavailability (AUC: 3142 [1344‐14573] pg/mL*hours) and reached pharmacological peak concentration (388 [132‐1583] pg/mL). Conclusions: SLN‐melatonin enterally administered offers favourable pharmacokinetics in critically ill patients, with higher bioavailability with respect to the standard formulation; μE‐TD provided effective pharmacological blood levels, with a time‐concentration profile more similar to the physiological melatonin pattern. [ABSTRACT FROM AUTHOR]

• Lipids were evaluated as donepezil cutaneous enhancer for screening NLC components. • DPB-NLC were prepared employing lecithin due its enhancing effect for donepezil. • Spherical and uniformly nano-sized DPB-NLC were obtained. • DPB-NLC-gel showed a release profile with burst effect followed by sustained release. • DPB-NLC-gel showed suitable as transdermal delivery systems of DPB. Donepezil is one of the main compounds used in the therapy of Alzheimer's disease. Oral administration of this drug presents many drawbacks, resulting in treatment non-adherence among patients. Thus, the development of transdermal formulations for donepezil delivery is important. The aim of this study was to prepare and to evaluate nanostructured lipid carrier-based gels (NLC gel) able to improve the skin delivery of donepezil free base (DPB). The components of nanostructured lipid carriers (NLCs) were selected after evaluating their enhancing effects using in vitro DPB skin delivery assays. DPB-loaded NLC were prepared by a microemulsion technique, by employing stearic acid as a solid lipid, oleic acid as a liquid lipid, lecithin as a surfactant, and sodium taurodeoxycholate as a co-surfactant. The DPB-NLC dispersions were characterized morphologically using atomic force microscopy and physicochemically using dynamic light scattering and surface charge measurements. These data along, with the encapsulation studies, indicated that uniformly nano-sized particles with high drug encapsulation were fabricated. In vitro skin permeation assays were performed, and the results indicated that drug skin permeation from DPB-NLC gel was increased, not only by the enhancing effect of their components, but the lipid nanocarriers also presented an additional enhancing effect to increase drug flux across the skin. Therefore, DPB-NLC gel is an interesting formulation for the enhanced treatment of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

The purpose of this study was to improve the solubility of resveratrol (Res) by a self-microemulsifying drug-delivery system (SMEDDS). Through a solubility experiment, the pseudoternary phase diagram and ternary phase diagram were used to optimize the Res SMEDDS formula. The optimum formulation consisted of 5% IPM, 20% PEG400, and 65% Cremophor RH40. The water solubility, stability, in vitro release and antioxidant activity of the Res SMEDDS were characterized. The Res solubility in the SMEDDS was at least 1,000 times compared to that in water. The average droplet size of the microemulsion was 28.00±1.67 nm and uniform distribution. The Res SMEDDS should be stored at low temperature and in the dark to avoid light conditions. Res SMEDDS was able to improve the in vitro release rate of Res, and the in vitro release of Res from Res SMEDDS was significantly faster that of Res powder and unaffected by pH value of media. Antioxidant assays showed that antioxidant activities of Res in Res SMEDDS were unaffected compared to Res powder. Cytotoxicity study indicated that Res SMEDDS at the concentration of less than 100 μM was safe. These results demonstrated the potential use of Res SMEDDS for oral administration of Res. [ABSTRACT FROM AUTHOR]

Abstract Biopolymer nanoparticles can be used as key and versatile components in colloidal delivery systems that have numerous food and pharmaceutical applications. Various methods have been employed for the fabrication of biopolymer nanoparticles. However, many conventional methods are infeasible for the synthesis of biopolymer nanoparticles because they involve energy-, time- and, material-consuming protocols. The use of miroemulsions is a novel and alternative approach for the synthesis of biopolymer nanoparticles. The composition and structure of microemulsions can be optimized to tailor nanoparticle characteristics. In this review, different microemulsion-based procedures for the synthesis of biopolymer nanoparticles are discussed, including single and double microemulsion-based methods. The major parameters affecting the size of biopolymer nanoparticles are also summarized. In addition, current challenges and future research directions in the preparation of biopolymer nanoparticles using reverse microemulsions are discussed. Highlights • Microemulsion composition and structure can be tuned to customize nanoparticle features. • Microemulsion-based synthesis includes single and double microemulsion-based methods. • All-natural plant-based biopolymeric nanoparticles can be produced by food-grade solvents. • Recovering the oil phase and surfactant is promising for commercial applications. [ABSTRACT FROM AUTHOR]

Abstract Characterizing protein aggregates in the presence of silicone oil is a long standing challenge for the pharmaceutical industry. Silicone oil is often used as a lubricant in devices that deliver and store therapeutic protein products and has been linked to protein aggregation, which can compromise a drug's effectiveness or cause autoimmune responses in patients. Most traditional technologies cannot quantitatively distinguish protein aggregates and silicone oil in their native formulations for sizes less than 5 μm. We use holographic video microscopy to study protein aggregation to demonstrate its capability to quantitatively distinguish protein aggregates and silicone oil in the presence of varying amounts of the surfactants SDS and polysorbate 80 in the size range of 0.5-10 μm without the need for dilution or special sample preparation. We show that SDS denatures proteins and stabilizes silicone oil. We also show that polysorbate 80 may limit protein aggregate formation if it is added to an IgG solution before introducing silicone oil. [ABSTRACT FROM AUTHOR]

Abstract: Colloid science provides fundamental knowledge to fields such as the pharmaceutical, detergency, paint, and food industry. An exciting application is art conservation, which poses a challenge owing to the complex range of interfacial interactions involved in restoring artefacts. Currently, the majority of the most performing and environmentally safe cleaning and consolidation agents for artworks belong to soft matter and colloids. The development and application of increasingly complex systems, from microemulsions to semi‐interpenetrating hydrogels containing such fluids, is presented. These systems have been used on diverse artefacts, from Renaissance frescos to works by Picasso and Pollock. Chemical design can be implemented to meet the requirements of curators, and knowledge of the colloid structure and dynamics can overcome serendipitous approaches of traditional conservation practice. Future perspectives for soft matter and colloid science in the field of cultural heritage preservation are also summarized. [ABSTRACT FROM AUTHOR]

Background. Artesunate is one of the most potent, rapidly acting and therapeutically versatile antimalarial drugs. Its efficacy is hampered by poor aqueous solubility and stability resulting in low oral bioavailability. Recent efforts to nanoformulate artesunate have shown great potential of improving its dissolution profile and bioavailability. However, no study has yet been done to investigate the intestinal permeability of these nanoformulations, which is a critical determinant of systemic absorption. Objective of the Study. The main aim of the study was to determine the intestinal permeability of artesunate-loaded solid lipid nanoparticles (SLN). Method. The microemulsion dilution technique was used to fabricate artesunate-loaded solid lipid nanoparticles. In vitro drug release studies were performed at pH 1.2 and 6.8 using the dialysis membrane method. The everted gut sac method was used to assess the intestinal permeability of the prepared nanoparticles. Results. The average particle size was 1109 nm and the polydispersity index (PDI) was 0.082. The zeta potential was found to be −20.7 mV. The encapsulation efficiency of the solid lipid nanoparticles obtained was 51.7%. At both pH 1.2 and 6.8, pure artesunate was rapidly released within the first 30 mins while the SLN showed a biphasic release pattern with an initial burst release during the first hour followed by a prolonged release over time. The rate of drug release increased with increasing pH. The apparent permeability (Papp) of SLN was found to be greater (0.169 mg/cm2) as compared to that of pure artesunate (0.117 mg/cm2) at the end of the experiment. Conclusion. The results obtained in this study showed that the microemulsion dilution technique can be used to formulate artesunate solid lipid nanoparticles. The formulation exhibited a sustained drug release profile. The intestinal permeability of artesunate could be enhanced by the nanoformulation. [ABSTRACT FROM AUTHOR]

• Ternary phase diagrams of tea tree oil, mixed surfactant and water are successfully established. • Mixed surfactant consists of an alkyl polyglucoside and propylene glycol as co-surfactant. • Gel-like structure is confirmed through dynamic oscillatory measurement. • Hydrogel is formed in TTO/mixed surfactant with (30 – 50) wt% water added. • Microemulsions from 1 wt% tea tree oil and 9 wt% mixed surfactants are stable for > 1 month. The purpose of this study was to develop the colloidal formulation, based on microemulsions and hydrogels, of Melaleuca alternifolia oil (aka tea tree oil, TTO) using a sustainable and biocompatible alkyl polyglucoside (APG) surfactant, Glucopon 600 CSUP (G600), commonly formulated for personal-care and home-care products. The pseudo-ternary phase diagram of TTO-mixed surfactant-water was established with the water titration method at 25 °C. The mixed surfactants were composed of G600 and propylene glycol (PPG) as a co-surfactant at G600/PPG = 1/1, 2/1 and 3/1 (m/m). Colloid samples of one phase were further characterized with rheological measurements and dynamic light scattering (DLS) at 25 °C. The samples containing TTO/mixed surfactant = 1/9 (m/m) and water show single phase only. With increasing water contents, the aforesaid system changed from Newtonian to pseudo-plastic, reflecting the transition from micellar solution / microemulsion to hydrogel. Especially, the gel-like behavior was confirmed with the dynamic oscillatory measurements, in which storage moduli were always larger than loss moduli at any time and any frequency under a constant strain of 0.5 %. Microemulsions made of 1 wt% tea tree oil and 9 wt% mixed surfactants were stable for > 1 month as monitored by aggregate size by DLS. Photos of samples prepared from TTO/Smix (3:1) at 1/9 by mass along the water dilution Line 1–9. Hydrogel existed in the sample in the inverted vial, i.e. the second vial from the left. [Display omitted] [ABSTRACT FROM AUTHOR]

A heterogeneous pH buffer based on a colloidal emulsion containing ion-exchanger and lipophilic base is described that can be integrated into hydrogels without affecting their ion-exchange properties. Each sphere works on the basis of reversible ion-exchange of hydrogen ions with solution cations, acting as a pH buffer while staying removed from solution in the nonpolar core of the spheres. The ion-exchange mechanism is supported by titration experiments in aqueous emulsion, showing that the nature and concentration of the exchanging solution cations influences the buffer action, with increasing lipophilicity moving the equilibrium to lower pH values. Agarose gels with entrapped pH buffer emulsions and mounted in a transport cell are shown by zero current potentiometry to exhibit negligible permselective properties above an ionic strength of 1 mM, a behavior no different from unmodified agarose, with an observed ion-exchanger concentration of 7 mM in dry agarose. This suggests that such pH buffers do not give rise to substantial ion-exchange properties of the gel material. In a first attempt to control the pH in the vicinity of an electrode surface by this approach, the emulsion was entrapped in an agarose gel in direct contact with a pH electrode, demonstrating the ability to buffer such gel films. [ABSTRACT FROM AUTHOR]

Nanosystems such as microemulsions (ME) and nanoemulsions (NE) offer considerable opportunities for targeted drug delivery to and via the skin. ME and NE are stable colloidal systems composed of oil and water, stabilised by a mixture of surfactants and cosurfactants, that have received particular interest as topical skin delivery systems. There is considerable scope to manipulate the formulation components and characteristics to achieve optimal bioavailability and minimal skin irritancy. This includes the incorporation of established chemical penetration enhancers to fluidize the stratum corneum lipid bilayers, thus reducing the primary skin barrier and increasing permeation. This review discusses nanosystems with utility in skin delivery and focuses on the composition and characterization of ME and NE for topical and transdermal delivery. The mechanism of skin delivery across the stratum corneum and via hair follicles is reviewed with particular focus on the influence of formulation. [ABSTRACT FROM AUTHOR]

The syntheses of platinum nanoparticles (Pt NPs) using colloidal and microemulsion methods and different reducing agents (methanol, NaBH 4 , and N 2 H 4 ) have been compared systematically. The colloidal synthesis was based on polyvinylpyrrolidone (PVP) as capping agent and water and methanol-water mixtures as reaction media. The microemulsion syntheses were carried out using the water-in-oil (w/o) system formed by dioctyl sulfosuccinate sodium salt (AOT), n -heptane and water. The influence of PVP/Pt, reducing agent/Pt and water/AOT molar ratios was studied. The Pt NPs prepared were characterized by transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Both colloidal and microemulsion syntheses resulted in globular shaped NPs consisting mainly of a single crystal domain with fcc structure. Colloidal synthesis with methanol and NaBH 4 , yielded very stable NPs suspensions with small mean particle size (3–6 nm) and distributions extending from 2 to 10 nm. Narrower size distributions were obtained with NaBH 4 , whereas the use of N 2 H 4 led to oversized particles. The most important synthesis variable was the PVP/Pt ratio. In the case of the microemulsion method, a broader range of NPs mean size was obtained (1–7 nm). A better tailoring of the properties of the NPs was achieved varying the type of reducing agent, the reducing agent/Pt ratio and water/AOT ratio. The conditions for the synthesis of NPs suspensions with well differentiated mean size and distribution were identified. [ABSTRACT FROM AUTHOR]

Emulsion technology has been utilized extensively in the pharmaceutical industry. This article presents a comprehensive review of the literature on an important subcategory of emulsions, microemulsions. Microemulsions are optically transparent, thermodynamically stable colloidal systems, 10–100 nm diameter, that form spontaneously upon mixing of oil, water and emulsifier. This review is the first to address advantages and disadvantages, as well as considerations and challenges in multi-drug delivery. For the period 1 January 2011–30 April 2016, 431 publications related to microemulsion drug delivery were identified and screened according to microemulsion, drug classification, and surfactant types. Results indicate the use of microemulsions predominantly in lipophilic drug delivery (79.4%) via oil-in-water microemulsions and non-ionic surfactants (90%) for oral or topical administration. Cancer is the disease state most targeted followed by inflammatory diseases, microbial infections and cardiovascular disease. Key generalizations from this analysis include: 1) microemulsion formulation is largely based on trial-and-error despite over 1200 publications related to microemulsion drug delivery since their discovery in 1943; 2) characterization using methods including interfacial tension, droplet size, electrical conductivity, turbidity and viscosity may provide additional information for greater predictability; 3) microemulsion drug delivery publications arise primarily from China (27%) and India (21%) suggesting additional research opportunities elsewhere. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin. Novel surfactant-based systems were successfully developed for loading trans -resveratrol to delivery to the brain. Systems with desired rheological, mechanical and mucoadhesive proprieties were achieved. Pharmacodynamic assays were performed in the induced-AD model and the systems were able to reverse the loss of memory and neuroinflammation followed by intranasal administration. [Display omitted] • Mixture of oleic acid, OLETH-20 and water was able to form self-orgnized systems; • Selected systems displayed as microemulsion and undergone to the lyotropic liquid crystals; • Rheological, mechanical and mucoadeshive studies showed in situ nasal suitable purposes; • Using in-vivo AD model, it was evidenced that treatment ameloriates memory and denotes decrease of neuroinflammation; [ABSTRACT FROM AUTHOR]

Surfactants (or amphiphiles) are generally believed to be a necessary component of microemulsions. However, research has found that in the absence of traditional surfactants, microemulsions can also form in a ternary system of two immiscible fluids and an “amphi-solvent”. Such microemulsions are called “surfactant-free microemulsions” (SFMEs). The so-called amphi-solvent is a solvent that is completely or at least partially miscible with each of the two immiscible fluids. The structures and properties of SFMEs are similar to those of traditional surfactant-based microemulsions (SBMEs) to some extent. This review focuses on recent advances in SFMEs, including their phase behavior, structures, properties and potential applications. [ABSTRACT FROM AUTHOR]

The dynamical properties of nanogels of xanthan gum (XG) with hydrodynamic radius controlled in a size range from 5 nm to 35 nm, were studied at the different XG concentrations in water/sodium bis-2-ethylhexyl-sulfosuccinate (AOT)/decane reverse micelles (RMs) vs. mass fraction of nano-droplet (MFD) at W = 40, using dynamic light scattering (DLS). The diffusion study of nanometer-sized droplets by DLS technique indicated that enhancing concentration of the XG polysaccharide resulted in exchanging the attractive interaction between nano-gels to repulsive interaction, as the mass fraction of nano-droplets increased. The reorientation time ( τ r ) of water nanodroplets decreased with MFD for water-in-oil AOT micro-emulsion comprising high concentration (0.0000625) of XG. On the other hand, decreasing concentration of biopolymer led to increasing the rotational correlation time of water nanodroplets with MFD. In conclusion, a single relaxation curve was observed for AOT inverse microemulsions containing different XG concentrations. Furthermore, the interaction between nanogels was changed from attractive to repulsive versus concentration of XG in the AOT RMs. [ABSTRACT FROM AUTHOR]