Development of multiple W/O/W emulsions as dermal carrier system for oligonucleotides: effect of additives on emulsion stability

Influence of different electrolytes and oils on the stability of W1/O/W2 double emulsion during storage and in vitro digestion

The aim of this study is to formulate a stable water-in-oil-in-water (W1/O/W2) double emulsion using different types of oils and electrolytes. W1/O was formulated with different electrolyte solutions (W1) dispersed in various oils (O) using polyglycerol polyricinoleate as a stabilizer. External aqueous phase was Tween-80 (W2), and W1/O dispersed in W2 was used. The emulsion containing NaCl or MgCl2 exhibited high encapsulation efficiency (EE) and maintained particle size. Regarding the oil type, the emulsion with MCT oil showed a small droplet size and a high viscosity and EE, presenting a stable droplet distribution in optical observation. The stability of emulsion containing NaCl was maintained during the in vitro digestion experiments. MCT oil, NaCl and MgCl2 have the potential to produce stable double emulsions for storage stability and in vitro digestion studies. The findings would be useful for preparing stable double emulsions used in the food and cosmetic industries.

Assessing and Predicting Physical Stability of Emulsion-Based Topical Semisolid Products: A Review

The emulsion-based topical semisolid dosage forms present a high degree of complexity due to their microstructures which is apparent from their compositions comprising at least two immiscible liquid phases, often times of high viscosity. These complex microstructures are thermodynamically unstable, and the physical stability of such preparations is governed by formulation parameters such as phase volume ratio, type of emulsifiers and their concentration, HLB value of the emulsifier, as well as by process parameters such as homogenizer speed, time, temperature etc. Therefore, a detailed understanding of the microstructure in the DP and critical factors that influence the stability of emulsions is essential to ensure the quality and shelf-life of emulsion-based topical semisolid products. This review aims to provide an overview of the main strategies used to stabilize pharmaceutical emulsions contained in semisolid products and various characterization techniques and tools that have been utilized so far to evaluate their long-term stability. Accelerated physical stability assessment using dispersion analyzer tools such as an analytical centrifuge to predict the product shelf-life has been discussed. In addition, mathematical modeling for phase separation rate for non-Newtonian systems like semisolid emulsion products has also been discussed to guide formulation scientists to predict a priori stability of these products.

Current Advances in Lipid Nanosystems Intended for Topical and Transdermal Drug Delivery Applications

Skin delivery is an exciting and challenging field. It is a promising approach for effective drug delivery due to its ease of administration, ease of handling, high flexibility, controlled release, prolonged therapeutic effect, adaptability, and many other advantages. The main associated challenge, however, is low skin permeability. The skin is a healthy barrier that serves as the body's primary defence mechanism against foreign particles. New advances in skin delivery (both topical and transdermal) depend on overcoming the challenges associated with drug molecule permeation and skin irritation. These limitations can be overcome by employing new approaches such as lipid nanosystems. Due to their advantages (such as easy scaling, low cost, and remarkable stability) these systems have attracted interest from the scientific community. However, for a successful formulation, several factors including particle size, surface charge, components, etc. have to be understood and controlled. This review provided a brief overview of the structure of the skin as well as the different pathways of nanoparticle penetration. In addition, the main factors influencing the penetration of nanoparticles have been highlighted. Applications of lipid nanosystems for dermal and transdermal delivery, as well as regulatory aspects, were critically discussed.

Effects of W/O Nanoemulsion on Improving the Color Tone of Beijing Roast Duck

Traditional Beijing roast duck is often brushed with a high concentration of maltose solution (15% w/v) and shows ununiform color after roasting. A novel W/O nanoemulsion was applied to improve the color tone of Beijing roast ducks and, meanwhile, reduced the amount of sugar. For the W/O emulsion, 3% (w/v) xylose solution as the aqueous phase, soybean oil as the oil phase, and polyglycerol polyricinoleate (PGPR) and whey protein isolate (WPI) as co-emulsifiers were fabricated by high-pressure homogenization. Particle size measurement by Zetasizer and stability analysis by Turbiscan stability analyzer showed that WPI as co-emulsifier and internal aqueous phase at pH 9 decreased the droplet size and improved the emulsion stability. In addition, by color difference evaluation, the W/O nanoemulsion improved the Maillard reaction degree and color tone of Beijing roast duck. The molecular structure and key composition of pigments on the surface of Beijing roast duck skins were also identified and characterized by UV-vis spectroscopy and UHPLC-MS. This study creatively offers theoretical guidance for increasing applications of W/O-nanoemulsion-based Maillard reaction in the roast food industry, especially for the development of reduced-sugar Beijing roast duck with uniform and desired color satisfying consumers' acceptance and marketability.

Recent Developments of Carboxymethyl Cellulose

Carboxymethyl cellulose (CMC) is one of the most promising cellulose derivatives. Due to its characteristic surface properties, mechanical strength, tunable hydrophilicity, viscous properties, availability and abundance of raw materials, low-cost synthesis process, and likewise many contrasting aspects, it is now widely used in various advanced application fields, for example, food, paper, textile, and pharmaceutical industries, biomedical engineering, wastewater treatment, energy production, and storage energy production, and storage and so on. Many research articles have been reported on CMC, depending on their sources and application fields. Thus, a comprehensive and well-organized review is in great demand that can provide an up-to-date and in-depth review on CMC. Herein, this review aims to provide compact information of the synthesis to the advanced applications of this material in various fields. Finally, this article covers the insights of future CMC research that could guide researchers working in this prominent field.

Fabrication and characterization of the W/O/W multiple emulsion through oleogelation of oil

W/O/W emulsions were easily prepared by oleogelation of the oil phase using rice bran wax (RBX) and their microstructure, stability, rheology and protection of proanthocyanidins and β-carotene were investigated. Formation of the W/O/W emulsion was confirmed using confocal laser scanning microscopy and staining of the inner aqueous phase by tartrazine. The average particle size and viscosity of the emulsion increased as the RBX concentration increased. Moreover, RBX increased the stability of the emulsion and the emulsion was the most stable when the RBX concentration was 8.0% or 10.0%. On the other hand, the W/O/W emulsions were used to simultaneously encapsulate proanthocyanidins and β-carotene. Specifically, proanthocyanidins and β-carotene in RBX-containing emulsions were more stable and had higher bioaccessibility than in the emulsion without RBX. Besides, both their chemical stability and bioaccessibility reached the maximum value when the RBX concentration was 8.0% or 10.0%. In summary, the optimal RBX concentration was 8.0%.

Tea polyphenols encapsulated in W/O/W emulsions with xanthan gum-locust bean gum mixture: Evaluation of their stability and protection

Herein, improvement of the stability of the water-in-oil-in-water (W/O/W) emulsions by addition of xanthan gum (XG)/locust bean gum (LBG) mixture in the inner water phase was aimed. The impact of XG/LBG mixture on the physical stability, microstructure and rheological properties of W/O/W emulsions was investigated. It was found that, compared with the control emulsions, the presence of XG/LBG mixture could improve the stability of W/O/W emulsions against coalescence. The tea polyphenols (TPPs) and XG/LBG mixture were simultaneously included in the internal aqueous phase of the double emulsion and stored at 25 and 40 °C in the dark for 28 d. The results showed that XG/LBG mixture not only had a protective role for TPPs encapsulated in the internal water phase, but also maintained more than 50% of the antioxidant capacity of TPPs.

Investigation Utilizing the HLB Concept for the Development of Moisturizing Cream and Lotion: In-Vitro Characterization and Stability Evaluation

The current study aims to utilize the concept of the hydrophilic–lipophilic balance (HLB) value of ingredients for the development of a stable emulsion-based moisturizing cream and lotion for cosmetic application. The combination of a hydrophilic and lipophilic emulsifier such as glyceryl stearate (HLB value 3.8) and PEG-100 stearate (HLB value 18.8) were found to be effective to emulsify the chosen oil phase system at a specific concentration to achieve the required HLB for the development of the stable emulsion-based system. The developed formulation was characterized for pH, viscosity, spreadability, rheology, and droplet morphology. The influence of carbopol® ETD 2020 and the concentration of the oil phase on the rheology of the product was investigated and found to be significant to achieve the required thickening to convert the lotion into a cream. The formulation system developed through utilizing the concept of HLB was compared to a product developed through the conventional approach. It was observed that the utilization of the HLB method for the development of an emulsion-based product is a promising strategy compared to the conventional method. The physical stability and thermodynamic stability tests were carried out under different storage conditions. It was observed that the developed formulation was able to retain its integrity without showing any signs of instability during storage.

Preparation of Ethyl Cellulose Microspheres for Sustained Release of Sodium Bicarbonate

Sustained release of thermal-instable and water-soluble drugs with low molecule weight is a challenge. In this study, sodium bicarbonate was encapsulated in ethyl cellulose microspheres by a novel solid-in-oil-in-oil (S/O/O) emulsification method using acetonitrile/soybean oil as new solvent pairs. Properties of the microspheres such as size, recovery rate, morphology, drug content, and drug release behavior were evaluated to investigate the suitable preparation techniques. In the case of that the ratio of the internal and external oil phase was 1: 9, Tween 80 as a stabilizer resulted in the highest drug content (2.68%) and a good spherical shape of microspheres. After the ratio increased to 1: 4, the microspheres using Tween 80 as the stabilizer also had high drug content (1.96%) and exhibited a sustained release behavior, with 70% of drug released within 12 h and a sustained release of more than 40 h. Otherwise, different emulsification temperatures at which acetonitrile was evaporated could influence the drug release behaviour of microspheres obtained. This novel method is a potential and effective method to achieve the encapsulation and the sustained release of thermal-instable and water-soluble drugs with low molecule weight.

Effects of Hydrophilic Carriers on Structural Transitions and In Vitro Properties of Solid Self-Microemulsifying Drug Delivery Systems

Self-microemulsifying drug delivery systems (SMEDDS) offer potential for improving the oral bioavailability of poorly water-soluble drugs. However, their susceptibilities during long term storage and in vivo precipitation issues limit their successful commercial application. To overcome these limitations, SMEDDS can be solidified with solid carriers, thus producing solid self-microemulsifying drug delivery systems (S-SMEDDS). In this study, effects of various hydrophilic carriers on structural transitions and in vitro properties of S-SMEDDS were investigated in order to set up in vitro methods for screening out appropriate carriers for S-SMEDDS. Liquid SMEDDS was prepared and characterized using nimodipine as a model drug. The effects of various hydrophilic carriers on internal microstructure and solubilization of SMEDDS were investigated by conductivity measurement and in vitro dispersion test. The results showed that hydrophilic carriers including dextran 40, maltodextrin and PVP K30 seemed to delay the percolation transition of SMEDDS, allowing it to maintain a microstructure that was more conducive to drug dissolution, thus significantly increasing the solubilization of nimodipine in the self-microemulsifying system and decreasing drug precipitation when dispersed in simulated gastric fluid. S-SMEDDS of nimodipine were prepared by using spray drying with hydrophilic carriers. The effects of various hydrophilic carriers on in vitro properties of S-SMEDDS were investigated by using SEM, DSC, PXRD and in vitro dissolution. The results showed that properties of hydrophilic carriers, especially relative molecular mass of carriers, had obvious influences on surface morphologies of S-SMEDDS, reconstitution of microemulsion and physical state of nimodipine in S-SMEDDS. Considering that in vitro properties of S-SMEDDS are closely related to their pharmacokinetic properties in vivo, the simple and economical in vitro evaluation methods established in this paper can be used to screen solid carriers of S-SMEDDS well.

Collagen peptide-loaded W1/O single emulsions and W1/O/W2 double emulsions: influence of collagen peptide and salt concentration, dispersed phase fraction and type of hydrophilic emulsifier on droplet stability and encapsulation efficiency

Collagen peptide-loaded double emulsions are developed by using various formulation parameters to utilize as food-grade functional ingredients with excellent droplet stability and encapsulation efficiency of collagen peptide.

Clotrimazole multiple W/O/W emulsion as anticandidal agent: Characterization and evaluation on skin and mucosae

Clotrimazole (CLT) was formulated in a multiple W/O/W emulsion (ME) with the aim of evaluating its potential as topical anticandidal agent and comparing with marketed products. A previously evaluated CLT-ME was selected and physicochemically characterized. The in vitro release behavior and the ex vivo permeation profiles were assessed using Franz diffusion cells using three different types of biological membranes: human skin and porcine buccal, sublingual and vaginal mucosae. The antifungal activity against Candida strains was also tested. Results showed CLT-MEs sizes of 29.206 and 47.678 μm with skin compatible pH values of 6.47 and 6.42 exhibiting high zeta potential values of -55.13 and -55.59 mV with dependence on the pH variation. The physicochemical stability was kept for a period of 180 days of storage at room temperature. CLT-MEs exhibited pseudoplastic behavior with hysteresis areas and viscosities of 286 and 331 mPa⋅s showing higher spreadability properties than commercial counterparts. An improved CLT release pattern was supplied by the ME system following a hyperbolic model. Likewise, ME system gave higher skin permeation flux of CLT than commercial reference. CLT amounts retained in the skin and mucosae were also higher than commercial references, which coupled with the higher antimycotic efficacy make CLT-MEs a great tool for clinical investigation of topical candidiasis treatments.

Iron Encapsulation in Water-in-Oil Emulsions: Effect of Ferrous Sulfate Concentration and Fat Crystal Formation on Oxidative Stability

Iron deficiency is a major global human health concern. Encapsulation of iron in functional food products may help to solve this problem. However, iron is highly reactive and may promote rapid lipid oxidation in fatty foods. In this study, the effect of ferrous sulfate (0.1 to 0.5 wt%) and rice bran stearin (0 or 30 wt%) on the physical properties, oxidative stability, and encapsulation efficiency of 20 wt% water-in-oil (W/O) emulsions stabilized with polyglycerol polyricinoleate was investigated. In the presence of rice bran stearin crystals in the continuous oil phase, W/O emulsions had smaller mean droplet diameters (d ∼ 250 nm) and better physical stability than its absence (d ∼ 330 nm). An increase in the ferrous sulfate concentration in the water droplets led to a decrease in the oxidative stability of the W/O emulsions. However, the presence of rice bran stearin significantly (P ≤ 0.05) improved their oxidative stability. Moreover, addition of rice bran stearin also significantly (P ≤ 0.05) improved the encapsulation efficiency and delayed ferrous sulfate release from the W/O emulsions. The impact of pH and ionic strength on the encapsulation efficiency of the W/O emulsion was also investigated. Ionic strength affected the encapsulation efficiency much more than pH. The W/O emulsions created in the present study may be useful for the encapsulation and delivery of iron and other water-soluble nutrients into food products.

PRACTICAL APPLICATION

Water-in-oil (W/O) emulsions may be used to encapsulate, protect, and deliver water-soluble bioactive compounds or nutrients into food products. In this study, W/O emulsions stabilized using an oil-soluble surfactant (polyglycerol polyricinoleate, PGPR) and fat crystal network (rice bran stearin) were shown to be useful for encapsulation and delivery of iron into foods. This strategy may be a promising approach to reduce iron deficiency, a major nutritional deficiency for people with inadequate food supplies.

The effects of biomacromolecules on the physical stability of W/O/W emulsions

The effect of bovine serum albumin (BSA), whey protein isolate (WPI), whey protein hydrolysate (WPH), sodium caseinate (SC), carboxymethylcellulose sodium (CMC), fish gelatin (FG), high methoxyl apple pectin (HMAP), low methoxyl apple pectin (LMAP), gum Arabic (GA), ι-carrageenan (CGN), and hydroxypropyl chitosan (HPCTS) on physical stability of internal or external aqueous phase of water-in-oil-in-water (W/O/W) emulsions was evaluated. WPI and CGN in the internal aqueous phase, and GA, HPCTS, and CMC in the external phase reduced the size of emulsion droplets. BSA, WPI, SC, FG, CGN, and HPCTS improved the dilution stability of W/O/W emulsions, but HMAP had a negative effect. BSA, WPI, SC, FG, LMAP, GA, CGN, HPCTS, or CMC significantly improved the thermal stability of W/O/W emulsions. Results also indicated that the addition of CGN (1.0%), HMAP (1.0%), WPH (1.0%), or HPCTS (1.0%) in internal aqueous phase significantly increased the viscosity of emulsions, however, addition to the external aqueous phase had insignificant effects. A protein-knockout experiment confirmed that proteins as biomacromolecules, were the key factor in improving physical stability of emulsions.

Development of Clotrimazole Multiple W/O/W Emulsions as Vehicles for Drug Delivery: Effects of Additives on Emulsion Stability

Multiple emulsions have attracted considerable attention in recent years for application as potential delivery systems for different drugs. The aim of the present work is to design a new formulation containing clotrimazole (CLT) loaded into multiple emulsions by two-step emulsification method for transdermal delivery. Different ingredients and quantities like primary and secondary co-emulsifiers and the nature of oily phase were assayed in order to optimize the best system for good. Resulting formulations were characterized in terms of droplet size, conductivity, pH, entrapment efficiency, rheological behavior, and stability under various storage conditions for 180 days. pH values of multiple emulsions containing CLT ranged from 7.04 ± 0.03 to 6.23 ± 0.04. Droplet size increased when increasing concentration of sorbitan stearate. The addition of polysorbate 80 resulted in significant decrease of oil droplet size comparing with those prepared without this. CLT entrapment efficiency ranged between 85.64% and 97.47%. All formulations exhibited non-Newtonian pseudoplastic flow with some apparent thixotropic behavior. Cross and Herschel-Bulkley equations were the models that best fitted experimental data. In general, the addition of 1% polysorbate 80 resulted in a decrease of viscosity values. No signals of optical instability were observed, and physicochemical properties remained almost constant when samples were stored at room temperature after 180 days. On the contrary, samples stored at 40°C exhibited pronounced increase in conductivity values 24 h after elaboration and some of them were unstable after 180 days of storage. JMLP01 was proposed as an innovative and stable system to incorporate CLT as active pharmaceutical ingredient.

Delivery of therapeutic RNA-cleaving oligodeoxyribonucleotides (deoxyribozymes): from cell culture studies to clinical trials

INTRODUCTION

Development of efficient in vivo delivery systems remains a major challenge en route to clinical application of antisense technology, including RNA-cleaving molecules such as deoxyribozymes (DNAzymes). The mechanisms of oligonucleotide uptake and trafficking are clearly dependent on cell type and the type of oligonucleotide analogue. It appears likely that each particular disease target would pose its own specific requirements for a delivery method. Areas covered. In this review we will discuss the available options for DNAzyme delivery in vitro and in vivo, outline various exogenous and endogenous strategies that have been, or are still being, developed and ascertain their applicability with emphasis on those methods that are currently being used in clinical trials. Expert opinion. The available information suggests that a practical system for in vivo delivery has to be biodegradable, as to minimize concerns over long-term toxicity, it should not accumulate in the organism. Extracellular vesicles may offer the most organic way for drug delivery especially as they can be fused with artificial liposomes to produce hybrid nanoparticles. Chemical modification of DNAzymes holds great potential to apply oligonucleotide analogs that would not only be resistant to nuclease digestion, but also able to penetrate cells without external delivery agents.

Room Temperature Consolidation of a Porous Poly(lactic-co-glycolic acid) Matrix by the Addition of Maltose to the Water-in-Oil Emulsion

In composite materials made of polymer matrices and micro-nano dispersed compartments, the morphology of the dispersed phase can strongly affect several features of the final material, including stability, loading efficiency, and kinetic release of the embedded molecules. Such a polymer matrix composite can be obtained through the consolidation of the continuous polymer phase of a water-in-oil (W/O) emulsion. Here, we show that the morphology of the dispersed phase in a poly(lactic-co-glycolic acid, PLGA) matrix can be optimized by combining an effective mild temperature drying process with the addition of maltose as a densifying compound for the water phase of the emulsion. The influence of this addition on final stability and consequent optimal pore distribution was theoretically and experimentally confirmed. Samples were analyzed in terms of morphology on dried flat substrates and in terms of rheology and interfacial tension at the liquid state. While an increase of interfacial tension was found following the addition of maltose, the lower difference in density between the two emulsion phases coming from the addition of maltose allowed us to estimate a reduced creaming tendency confirmed by the experimental observations. Rheological measurements also confirmed an improved elastic behavior for the maltose-containing emulsion.

Interfacial film stabilized W/O/W nano multiple emulsions loaded with green tea and lotus extracts: systematic characterization of physicochemical properties and shelf-storage stability

Background and aims

Multiple emulsions have excellent encapsulating potential and this investigation has been aimed to encapsulate two different plant extracts as functional cosmetic agents in the W/O/W multiple emulsions and the resultant system’s long term stability has been determined in the presence of a thickener, hydroxypropyl methylcellulose (HPMC).

Methods

Multiple W/O/W emulsions have been generated using cetyl dimethicone copolyol as lipophilic emulsifier and a blend of polyoxyethylene (20) cetyl ether and cetomacrogol 1000® as hydrophilic emulsifiers. The generated multiple emulsions have been characterized with conductivity, pH, microscopic analysis, phase separation and rheology for a period of 30 days. Moreover, long term shelf-storage stability has been tested to understand the shelf-life by keeping the generated multiple emulsion formulations at 25 ± 10°C and at 40 ± 10% relative humidity for a period of 12 months.

Results

It has been observed that the hydrophilic emulsifiers and HPMC have considerably improved the stability of multiple emulsions for the followed period of 12 months at different storage conditions. These multiple emulsions have shown improved entrapment efficiencies concluded on the release rate of conductometric tracer entrapped in the inner aqueous phase of the multiple emulsions.

Conclusion

Multiple emulsions have been found to be stable for a longer period of time with promising characteristics. Hence, stable multiple emulsions loaded with green tea and lotus extracts could be explored for their cosmetic benefits.

Stability of a cosmetic multiple emulsion loaded with green tea extract

Multiple emulsions are excellent and exciting potential systems for the delivery of useful cosmetic agents. The work describes stability of a multiple emulsion for cosmetic purpose, loaded with extract of Camellia sinensis L. (Theaceae) in concentration of 5%. The formulation constitutes of cetyl dimethicone copolyol and polyoxyethylene (20) cetyl ether as emulsifiers and was characterised and monitored for various physicochemical aspects. Centrifugation has no devastating effect on physical destabilization/phase separation observed for 30 days. Mean globule sizes of multiple droplets were found in the range of 10.29 ± 4.4 μm to 12.77 ± 5.1 μm and of inner droplets were in the range of 0.8 ± 0.4 μm to 1.6 ± 0.8 μm. All samples exhibited shear thinning behavior with increase in shear stress. The results of the present study indicate that multiple emulsions can be used as carrier of 5% Camellia sinensis L. extract to enhance desired effects. The developed physically and chemically stable system is an effective system for targeting skin layers; however, long-term stability at elevated temperatures may be needed with suitable modifications, if required.

Enrichment, development, and assessment of Indian basil oil based antiseptic cream formulation utilizing hydrophilic-lipophilic balance approach

The present work was aimed to develop an antiseptic cream formulation of Indian basil oil utilizing hydrophilic-lipophilic balance approach. In order to determine the required-hydrophilic lipophilic balance (rHLB) of basil oil, emulsions of basil oil were prepared by phase inversion temperature technique using water, Tween 80, and Span 80. Formulated emulsions were assessed for creaming (BE9; 9.8, BE10; 10.2), droplet size (BE18; 3.22 ± 0.09 μm), and turbidity (BE18; 86.12 ± 2.1%). To ensure correctness of the applied methodology, rHLB of light liquid paraffin was also determined. After rHLB determination, basil oil creams were prepared with two different combinations of surfactants, namely, GMS : Tween 80 (1 : 3.45) and SLS : GMS (1 : 3.68), and evaluated for in vitro antimicrobial activity, skin irritation test, viscosity and consistency. The rHLB of basil oil and light liquid paraffin were found to be 13.36 ± 0.36 and 11.5 ± 0.35, respectively. Viscosity, and consistency parameters of cream was found to be consistent over 90 days. Cream formulations showed net zone of growth inhibition in the range of 5.0–11.3 mm against bacteria and 4.3–7.6 mm against fungi. Primary irritation index was found to be between 0.38 and1.05. Conclusively stable, consistent, non-irritant, enriched antiseptic basil oil cream formulations were developed utilizing HLB approach.