Types Of Microemulsions Research Articles

Atomization behavior of burning stable emulsion droplets

We investigate the atomization behavior of burning stable water-in-oil microemulsion droplets. The microemulsion compositions are prepared by altering the dispersed phase volume fraction (ϕ) and base oils (dodecane, xylene, and surrogate (90% dodecane and 10% xylene) by weight). The combustion of base oil follows classical droplet combustion, while two-stage combustion, i.e., classical droplet combustion and atomization-dominated combustion, is observed for emulsion droplets. We reveal that vapor bubble formation occurs primarily through heterogeneous nucleation, and the mechanisms leading to bubble formation can be accurately predicted and controlled for distinct, highly stable emulsions. During the initial phase of combustion, water vapor bubbles nucleate, while the nucleation of oil vapor is more prevalent in the later phase of combustion due to the depletion of water content. In both regimes, heterogeneous nucleation ensues due to the agglomeration of surfactant inside the burning droplet. The lower volatility and viscous nature of the oil inhibit the growth rate of the nucleated oil-vapor bubble within the oil–surfactant mixtures. On the contrary, the water vapor bubble exhibits a higher growth rate within the emulsion droplet, attributed to its higher volatility and low viscosity. We show that qualitatively, the global bubble dynamics associated with the emulsion droplets remain substantially consistent regardless of ϕ and the type of base oil. However, it is observed that the onset of nucleation, bubble growth and collapse cycles, and the size of secondary droplets display a strong dependence on the ϕ and the type of base oil. The normalized diameter at the onset of nucleation increases as ϕ increases, exhibiting a logarithmic trend. The optimal dispersed phase volume fraction for effective atomization is found to be ϕ=0.2, regardless of the type of microemulsion.

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.

ADVANCEMENTS IN CIVIL EXPLOSIVES: NOVEL FORMULATIONS AND SUSTAINABLE FUEL SOLUTIONS

ABSTRACT. The article presents the development of a new explosive mixture based on agricultural ammonium nitrate, possessing high detonation capability, increased water resistance, and physical stability. The concept for its creation is based on obtaining an oil-in-water (O/W) type microemulsion, produced using vegetable oil. Calculations conducted showed that the use of 100 % rapeseed oil methyl esters compared to diesel fuel improves emulsification by 14 %, reducing emulsification time by 15 %. Due to the structure of the microemulsion, ordinary agricultural ammonium nitrate can successfully retain around 7.5 % of the microemulsion. This amount of fuel phase is sufficient for obtaining an explosive composition with an appropriate oxygen balance. Substituting the porous ammonium nitrate (PAN) with agricultural ammonium nitrate - the cheapest oxidizer for the production of the newly developed explosive mixture, reduces its production cost and significantly increases the competitiveness of the product.

Lessons Learned in Interfacial Tension Prediction Using a Mixture of Sulfonate- and Ethoxylate-based Surfactants in a Waxy Oil-brine System

The chemical-enhanced oil recovery (CEOR) method is applied to change reservoir rock or fluid characteristics by injecting alkaline, surfactant, and polymer or a combination of two or three of the compounds. Surfactant flooding improves oil recovery by reducing the interfacial tension between oil and water. Selecting reservoir surfactants, especially microemulsions, requires careful screening. This study predicted waxy oil system interfacial tension using surfactant mixtures at below- and above-optimum salinity. To predict the interfacial tension, microemulsion types, HLB, ideal salinity, and HLD were used. The study predicted oil-surfactant-water interfacial tension using SAE, FEO, and their mixtures. We improved the Huh equation by adding a fitting parameter, β, to accommodate the transition from type III to type II microemulsions as salinity increases. With increasing salinity, anionic surfactant’s hydrophilic-hydrophobic interactions change, affecting the values and surfactant layer thickness. This study improved hydrophilic-lipophilic deviation (HLDN) by establishing a fixed interval for nonionic surfactants. Van der Waals attraction, values and interface surfactant layer thickness are connected, reflecting the fact that lower values reduce interfacial tension better. This study also found that surfactant packing at the oil-water interface increases the order of the oil-solution ratio and the microemulsion values with polarity.

An effect of hydrophobicity of cosurfactant on the growth of cerium tetrafluoride hexagonal nanorods in water-in-oil microemulsion template

This study involves the effect of hydrophobicity of cosurfactants on the formation of cerium tetrafluoride nanoparticles inside the core of water-in-oil microemulsion. To produce the microemulsions, two distinct chain length cosurfactants, 1-butanol (4 carbon atoms) and 1-hexanol (6 carbon atoms) are employed. Dynamic light scattering (DLS) study reveals that, for both types of microemulsion, the synthesis of nanostructures typically occurs in three stages: nucleation phase (around first 15 min), transition phase (30–60 min) and growth phase (60–120 min). Microstructural analysis of Field Emission Scanning Electron Microscopy (FESEM) supports the evolution of hexagonal nanorods. In comparison to reverse micellar media based on 1-hexanol, 1-butanol based reverse micellar media participates in faster reaction. Longer hydrophobic chain length of 1-hexanol enhances the surface film rigidity and produces a well-defined phase boundary, which reduces intermicellar exchange and leads to the evolution of smaller hexagonal nanorods. Therefore, this study may assist the researcher to better understand how cosurfactants influence the growth of nanostructures of lanthanide series metal nanoparticles, using a microemulsion template.

Novel Microemulsions with Essential Oils for Environmentally Friendly Cleaning of Copper Cultural Heritage Artifacts.

Cleaning represents an important and challenging operation in the conservation of cultural heritage, and at present, a key issue consists in the development of more sustainable, "green" materials and methods to perform it. In the present work, a novel xylene-in-water microemulsion based on nonionic surfactants with low toxicity was obtained, designed as low-impact cleaning agent for metallic historic objects. Phase diagram of the mixtures containing polyoxyethylene-polyoxypropilene triblock copolymer Pluronic P84 and D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) as surfactants, water, ethanol and xylene was studied, and a microemulsion with low surfactant content was selected as suitable cleaning nanosystem. Essential oils (EOs) from thyme and cinnamon leaf were added to the selected microemulsion in order to include other beneficial properties such as anticorrosive and antifungal protection. The microemulsions with or without EOs were characterized by size, size distribution and zeta potential. The cleaning efficacy of the tested microemulsions was assessed based on their ability to remove two types of artificial dirt by using X-ray energy dispersion spectrometry (EDX), scanning electron microscopy (SEM), contact angle measurements and color analysis. Microemulsions exhibit high capacity to remove artificial dirt from model copper coupons in spite of very low content of the organic solvent. Both thyme and cinnamon oil loading microemulsions prove to significantly reduce the corrosion rate of treated metallic plates compared to those of bare copper. The antifungal activity of the novel type of microemulsion was evaluated against Aspergillus niger, reported as main treat in biocorrosion of historic copper artifacts. Application of microemulsion with small amounts of EOs on Cu plates inhibits the growth of fungi, providing a good fungicidal effect.

Preparation and Performance Study of Microemulsion Acid for Comprehensive Plugging Removal in Carbonate Reservoir.

Matrix acidification is one of the most effective stimulations to dissolve scales and remove damage in carbonate reservoirs. However, existing acid systems are difficult to dissolve organic and inorganic scales simultaneously, and complex multi-stage alternative injection often introduces new precipitation and damages the reservoir. Here, based on the retardation ability of emulsified acid and the stable structure of microemulsion, an oil-phase solvent was preferably selected, and the surfactant and cosurfactant were optimized to prepare an acid-in-oil type microemulsion acid capable of dissolving both organic and inorganic scales and high solubilizing for hydrochloric acid. Based on the rotating disc experiment, scale dissolution experiment and acid driving experiment, the acid-rock reaction kinetics, scale dissolution ability and acidizing and plugging removal performance of microemulsion acid in a carbonate reservoir were systematically studied and compared. The results show that Solvesso 150 (aromatic solvent) has the advantages of low toxicity, high flash point and high-scale dissolving ability. At NP-4: OP-10: A (cosurfactant) = 3:3:4, the microemulsion acid system has the strongest ability to solubilize hydrochloric acid and can solve the problem of low H+ concentration. The particle size of microemulsion acid is smaller compared to emulsified acid. At 60 °C, the mass transfer coefficient of microemulsion acid is 3.2 × 10-8 cm2/s, which is one order of magnitude less than that of emulsified acid. Microemulsion acid shows good solubility performance in dissolving organic and inorganic scales, and the comprehensive solubility of mixed scales can reach 98.28%. The stronger scale solubilization ability and lower acid-rock reaction rate enable microemulsion acid to form a thin and straight main wormhole, thus enhancing the acidizing and plugging removal effect. This study can solve the problem of poor hydrochloric acid solubilization ability of microemulsion acid to a certain extent, which provides theoretical and data support for the research and development of microemulsion acid and the efficient plugging removal technology for carbonate reservoirs.

Topical Microemulsions: Skin Irritation Potential and Anti-Inflammatory Effects of Herbal Substances.

Microemulsions (MEs) have gained prominence as effective drug delivery systems owing to their optical transparency, low viscosity, and thermodynamic stability. MEs, when stabilized with surfactants and/or co-surfactants, exhibit enhanced drug solubilization, prolonged shelf life, and simple preparation methods. This review examines the various types of MEs, explores different preparation techniques, and investigates characterization approaches. Plant extracts and bioactive compounds are well established for their utilization as active ingredients in the pharmaceutical and cosmetic industries. Being derived from natural sources, they serve as preferable alternatives to synthetic chemicals. Furthermore, they have demonstrated a wide range of therapeutic effects, including anti-inflammatory, antimicrobial, and antioxidant activities. However, the topical application of plant extracts and bioactive compounds has certain limitations, such as low skin absorption and stability. To overcome these challenges, the utilization of MEs enables enhanced skin absorption, thereby making them a valuable mode of administration. However, considering the significant surfactant content in MEs, this review evaluates the potential skin irritation caused by MEs containing herbal substances. Additionally, the review explores the topical application of MEs specifically for herbal substances, with an emphasis on their anti-inflammatory properties.

Exploring the Versatility of Microemulsions in Cutaneous Drug Delivery: Opportunities and Challenges.

Microemulsions are novel drug delivery systems that have garnered significant attention in the pharmaceutical research field. These systems possess several desirable characteristics, such as transparency and thermodynamic stability, which make them suitable for delivering both hydrophilic and hydrophobic drugs. In this comprehensive review, we aim to explore different aspects related to the formulation, characterization, and applications of microemulsions, with a particular emphasis on their potential for cutaneous drug delivery. Microemulsions have shown great promise in overcoming bioavailability concerns and enabling sustained drug delivery. Thus, it is crucial to have a thorough understanding of their formulation and characterization in order to optimize their effectiveness and safety. This review will delve into the different types of microemulsions, their composition, and the factors that affect their stability. Furthermore, the potential of microemulsions as drug delivery systems for skin applications will be discussed. Overall, this review will provide valuable insights into the advantages of microemulsions as drug delivery systems and their potential for improving cutaneous drug delivery.

Effect of water content on stratum corneum penetration mechanism of W/O type microemulsions.

The stratum corneum (SC) consists of a lipid layer that forms two types of lamellar structures: short lamellar (S-La) and long lamellar (L-La). It has been reported that S-La contains water phases in the hydrophilic region of the lipids, and that it may play an important role in regulating the water content of the SC. The amount of water in the SC can affect how a drug carrier permeates through the intercellular lipid pathway. To better understand the impact of SC water content on the skin penetration mechanism of a microemulsion (ME), we conducted a study using small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and small-angle neutron scattering (SANS). Our results showed that MEs can enhance skin permeation under humid conditions because the lipid packing structures of the hydrated SC are more disrupted than those of the dry SC. The results also showed that the inner water of MEs was released to the SC when applying MEs to the dry SC, resulting in an increase in the repeat distance of S-La. Conversely, when MEs are applied to hydrated SC, the MEs absorb the water from the SC into their inner phases, causing a decrease in the repeat distance of S-La over time.

Interaction of Foam and Microemulsion Components in Low-Tension-Gas Flooding

Low-Tension-Foam (LTF) flooding is an emerging enhanced oil recovery technique for low-permeability carbonate reservoirs. Foam capacity is closely related to the salinity environment (or, equivalently, the phase behavior of the oil/water/surfactant system). Therefore, the interactions between microemulsion and foam components are of primary importance in the LTF process. In this study, the phase behavior of an oil/water/surfactant system under equilibrium is analyzed, firstly by assuming perfect mixing. Meanwhile, the formation kinetics of microemulsion are monitored through a novel low-field NMR technique, which is able to provide quantitative assessment on the microemulsion evolution characteristics. Then, foam stability is examined in the absence and in the presence of Winsor-I and Winsor-III type microemulsions. It is revealed that foam stability depends on the oil solubilization (oil swollen micelle size). A decrease in the oil swollen micelle size and micellar structure effectiveness, in conjunction with an increasing salinity, leads to lower foam stability in the presence of a Winsor-III type microemulsion.

Investigation of feasibility of alkali–cosolvent flooding in heavy oil reservoirs

Cold production is a challenge in the case of heavy oil because of its high viscosity and poor fluidity in reservoir conditions. Alkali–cosolvent–polymer flooding is a type of microemulsion flooding with low costs and possible potential for heavy oil reservoirs. However, the addition of polymer may cause problems with injection in the case of highly viscous oil. Hence, in this study the feasibility of alkali–cosolvent (AC) flooding in heavy oil reservoirs was investigated via several groups of experiments. The interfacial tension between various AC formulations and heavy crude oil was measured to select appropriate formulations. Phase behavior tests were performed to determine the most appropriate formulation and conditions for the generation of a microemulsion. Sandpack flooding experiments were carried out to investigate the displacement efficiency of the selected AC formulation. The results showed that the interfacial tension between an AC formulation and heavy oil could be reduced to below 10−3 mN/m but differed greatly between different types of cosolvent. A butanol random polyether series displayed good performance in reducing the water–oil interfacial tension, which made it possible to form a Type III microemulsion in reservoir conditions. According to the results of the phase behavior tests, the optimal salinity for different formulations with four cosolvent concentrations (0.5 wt%, 1 wt%, 2 wt%, and 3 wt%) was 4000, 8000, 14000, and 20000 ppm, respectively. The results of rheological measurements showed that Type III microemulsion had a viscosity that was ten times that of water. The results of sandpack flooding experiments showed that, in comparison with waterflooding, the injection of a certain AC formulation slug could reduce the injection pressure. The pressure gradient during waterflooding and AC flooding was around 870 and 30–57 kPa/m, respectively. With the addition of an AC slug, the displacement efficiency was 30%–50% higher than in the case of waterflooding.

Investigations on the enhanced oil recovery capacity of novel bio-based polymeric surfactants

Chemical enhanced oil recovery (cEOR) remains one of the most potent tertiary recovery methods. However, because of the complexity, cost, and environmental risks, attention is shifting towards bio-based polymeric surfactants as a possible alternative. Due to its vast abundance, cellulose has been identified as a source and cheap means of developing bio-based chemicals for oil recovery. In this study, novel hydrophobically modified cellulose sulphates, DPEA-Cell-OSO3−I (D-I) and DPEA-Cell-OSO3−II (D-II), were synthesized via microwave-assisted REDOX-mediated free-radical random copolymerization. Molecular characterization using nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) revealed their unique molecular features. In particular, D-II is identified as a mesoporous material. Rheological studies carried out on an economic concentration range of 50 to 1500 ppm showed that the novel products have moderate thickening properties, with viscosities less than 100 cP. Furthermore, it was discovered that the fluids are thermo-viscosifying and dilatant as well. Interfacial tension investigations revealed that they are surface-active with interfacial tension (IFT) lowering profiles improving with temperature as well, dropping down to the levels of 0.01 mN/m for D-I. They also demonstrated strong emulsifying capacity as Windsor types –II, +II, and middle phase microemulsion type III were produced during spontaneous emulsification tests. During coreflooding, D-I and D-II attained recoveries of 36 % and 53 %, respectively, over waterflood. D-II in particular had a very high residual resistant factor of 80, which is attributed to its dilatant nature, and emulsifying capabilities. In all, the properties and performances of the novel cellulose sulphate derivatives were linked to their molecular structures and architectures. Most importantly, these bio-based EOR materials will be suitable for high-temperature reservoirs.

Role of mucoadhesive agent in oculardelivery ofganciclovir microemulsion: cytotoxicity evaluation in vitro and ex vivo.

The aim of the present study was to investigate increase in delivery of drug upon formulation as mucoadhesive microemulsion system and further to investigate possibility of any cytotoxic effects using such formulation. Considering hydrophilic and small molecular nature of the drug, it was attempted to be formulated as microemulsion, by using pseudo ternary phase diagram method. Thus, three types of microemulsions were prepared; oil in water, water in oil type and chitosan-coated microemulsion. These microemulsions were characterized for several physicochemical properties like size, zeta potential, Polydispersity index, and compared for in vitro cell viability and ex vivo corneal irritation study. All three microemulsions were quite stable, transparent and homogenous systems. They showed similar drug release pattern, but highest ex vivo goat corneal permeation was observed with Chitosan coated microemulsion when compared with ganciclovir solution. All microemulsions were found to be non-irritant in in vitro cell viability assay and ex vivo corneal irritation study, indicating the potential of using such systems for delivery of drug to eye.

Microemulsions; A Mini Review

The review goes into great detail about the microemulsions' characteristics, structure, kinds, theories, characterization, and applications. They may be made easily by mixing the various ingredients together without the need for special tools or circumstances. Unlike the o/w type microemulsion, which has an aqueous continuous phase and oil droplets distributed in it, the w/o type microemulsion has oil as the continuous phase and water as droplets are disseminated in it. Microemulsions are classified into four primary categories based on different phase systems, and they are often utilized in the pharmaceutical and cosmetics sectors as well as in analytical methods. The design of medicine formulations and cosmetics may benefit from having a thorough understanding of the physicochemical and biological characteristics of microemulsions.

A novel approach in the treatment of osteoarthritis: In vitro and in vivo evaluation of Allium sativum microemulsion

AbstractOsteoarthritis (OA) is the most prevalent kind of joint disease, affecting millions of individuals worldwide. Allium sativum L. was used as a therapeutic agent in the microemulsion system against osteoarthritis due to allicin's high antioxidant and anti‐inflammatory effects. HPLC was used to evaluate the chemical components of the Allium sativum methanol extract. Water‐in‐oil (w/o) type of microemulsions loaded with Allium sativum extract was produced. To create the microemulsions, a titration approach was employed. The microemulsions were prepared using isopropyl myristate (IPM) as oil, Polysorbate 60, Sorbitan monolaurate 80 as surfactants, and Polyethylene glycol 400, ethanol as cosurfactants. The pH, droplet size, viscosity, polydispersity index values were measured to characterize of microemulsions. In addition, L929 healthy mouse fibroblasts and CHON‐001 healthy human cartilage fibroblast cells were tested for cytocompatibility in vitro. The therapeutic potential of Allium sativum microemulsion was investigated in rats that had osteoarthritis surgically simulated. HPLC analysis revealed a significant concentration of allicin in the extract. The titration approach was used to create an A. sativum microemulsion (AS) with a narrow droplet size and PDI range. In L929 and CHON‐001 cells, cytocompatibility experiments revealed that the maximum dosages of AS microemulsion 5% (v/v) exerted 93.41 ± 3.11% and 75.59 ±2.69% cell viabilities, respectively. Different concentrations of AS (1.25%, 2.5%, and 5% v/v) demonstrated cytoprotective efficacy against H2O2‐induced oxidative damage. When compared to the control group, in vivo investigations revealed fewer irregularities on the articular surface and typically arranged chondrocytes in the positive control and treated groups.

Emulgels Containing Perilla frutescens Seed Oil, Moringa oleifera Seed Oil, and Mixed Seed Oil: Microemulsion and Safety Assessment.

P. frutescens seed oil and M. oleifera seed oil consist of fatty acids and sterols that are beneficial for skin. Mixing of these oils at 1:1 ratio has shown to increase antioxidant activity of oils. This study aims to formulate emulgels containing microemulsions of P. frutescens seed oil, M. oleifera seed oil, and mixed P. frutescens and M. oleifera seed oils. The chemical constituents of P. frutescens seed oil, M. oleifera seed oil, and mixed seed oil are analyzed by gas chromatography/mass spectrometry (GC/MS). The microemulsions are formulated by a phase titration method and characterized for the droplet size, polydispersity index, and zeta potential value using a dynamic light scattering technique. The physical and chemical stability of the microemulsions are investigated using a rheometer and UV-Visible spectrophotometer, respectively. The safety of microemulsion is evaluated on PBMC and human subjects. Emulgels containing three different types of microemulsion are formulated. The results show that P. frutescens seed oil is mainly composed of alpha-linolenic acid, linoleic acid, and oleic acid, whereas M. oleifera seed oil contains a high proportion of oleic acid. Mixed seed oil contains a comparable amount of alpha-linolenic acid and oleic acid. All types of oils are composed of β-sitosterol as the major plant sterol. Microemulsions of all types of oils are successfully prepared by using Tween 80 as a surfactant due to the largest transparent region of pseudoternary phase diagram. The size, polydispersity index, and zeta potential values of all types of microemulsion are in the acceptable range upon storage at 30 °C for 1 month. Microemulsions exhibit pseudoplastic flow behavior. The percent of remaining oils in all types of microemulsion is more than 90% after storage at 30 °C for 1 month. Emulgels containing three types of microemulsions exhibit good characteristics and no change in viscosity after storage at 4, 30, and 45 °C for 1 month. The safety results reveal that three types of microemulsion do not induce cytotoxicity to PBMC nor induce skin irritation and allergic reactions. Emulgels containing microemulsions developed in this study can be used to safely deliver P. frutescens seed oil, M. oleifera seed oil, and mixed seed oil to human skin.

Effect and mechanism of microemulsion on low-rank coal flotation by mixing AEO-3 and diesel oil

ABSTRACT Low-rank bituminous coal has a low degree of metamorphism, a high oxygen content, and poor hydrophobicity. When using a conventional collector, it renders a low yield of clean coal, making it difficult to improve the quality via flotation. In this work, a type of diesel microemulsion (C1) was prepared using primary alcohol ethoxylate (AEO-3), which was adopted to conduct flotation. The results demonstrated that compared with a conventional diesel collector, the yield of clean coal was increased by 44.37%; the content of tailing ash was increased by 37.60%; the combustible recovery rate was improved by 55.65%, respectively; and the flotation kinetic constant was increased by 0.505. The addition of AEO-3 could significantly reduce the surface tension and generate smaller emulsion droplets, which could also adhere to coal particles, easily enhancing their hydrophobicity. An X-ray photoelectron spectroscopy analysis and its contact angle verify a significant enhancement in the hydrophobicity of the coal surface. More importantly, a molecular dynamic simulation revealed that adding AEO-3 could augment the electrostatic interaction between the collector (diesel) molecules and coal particles, as well as reduce the mean square displacement, i.e., the adsorption strength between the collector molecules and coal particles. On the other hand, the microemulsion could improve the hydrophobicity and floatability of coal particles and enhance the wrap angle of particle-bubble. And accelerating the generation of stable mineral flocculation, which was the main reason for the faster flotation process.

Development and Characterization of topical microemulsion as novel drug delivery system for Dapsone

Dapsone is a Biopharmaceutical Classification System class II drug with anti inflammatory, immunosuppressive, antibacterial, and antibiotic properties and is used as an antileprotic. The purpose of the present study was to investigate the potential of a microemulsion formulation for topical delivery of dapsone to enhance permeation and to avoid systemic side effects. When administered orally, dapsone undergoes hepatic metabolism. Its hepatic metabolite, dapsone hydroxylamine, shows systemic side effects such as hemolytic anaemia peripheral neuropathy, nausea, and headache. A novel drug delivery system in the form of a microemulsion was developed for dapsone. This is the first attempt that dapsone has been combined with chaulmoogra oil in a topical microemulsion. The primary drugs used for the treatment of leprosy are found in chaulmoogra seeds. Considering its good solubilizing capacity and its use in the treatment of leprosy, chaulmoogra oil was chosen as the oil phase. Based on emulsification ability, Cremophor RH40 and PEG 400 were selected as surfactant and co-surfactant, respectively. A pseudo-ternary phase diagram was constructed to identify the microemulsion region. Smix (Cremophor RH40: PEG-400 in the ratio of 1:2) was most effective in imparting stability to the formulation. The selected formulation exhibited appropriate diffusion behavior (in vitro). The developed dapsone containing microemulsion formulation exhibited the optimal homogeneity, clarity, pH, type of microemulsion, viscosity, percent drug content, and percent transmittance to qualify as a topical drug delivery system for local treatment of leprosy.

Lipophilic probe behavior in microemulsions evaluated by fluorescence correlation spectroscopy.

We evaluated the dispersion and diffusion of fluorescent-labeled lipophilic vitamin E (VE) in microemulsions (MEs) including water-in-oil (W/O) type ME, oil-in-water (O/W) type ME, and bicontinuous ME (BME), using fluorescence correlation spectroscopy (FCS). We prepared a fluorescent ATTO 488 or BODIPY group labeled VE (VE-ATTO or VE-BODIPY). VE-ATTO possesses lipophilic and hydrophilic parts, while VE-BODIPY consists solely of the lipophilic part. The VE-ATTO dissolved in heptane solution as an oil phase appeared hot pink in color due to the solvatochromism effect under room light and almost no fluorescent signal, which was unlike the VE-ATTO dissolved in ME solutions and all the VE-BODIPY solutions (typical fluorescent green color). The FCS measurement proved that VE-BODIPY diffuses faster than VE-ATTO. This is presumably because the "surfactant-like" VE-ATTO is localized and trapped at the micro-water/micro-oil interface of the MEs, while the VE-BODIPY exists in the ME phase and macro-oil phase with good dispersion. These results demonstrate that FCS is a powerful tool for the rapid evaluation of the lipophilic probe behavior in heterogeneous ME solutions.