Type Of Oil Phase Research Articles

Influence of Oil Polarity and Cosurfactants on the Foamability of Mono- and Diacylphosphatidylcholine Stabilized Emulsions.

Foam formulations are safe and effective therapy options for the treatment of chronic skin conditions that require the application of a topical formulation to delicate skin areas, such as scalp psoriasis or seborrheic dermatitis. This study focused on the development of foamable emulsions based on aqueous phospholipid blends. The effects of cosurfactants (nonionic Lauryglucoside (LG); zwitterionic Lauramidopropyl betaine (LAPB)), as well as of oil phases of different polarities, namely paraffin oil (PO), medium-chain triglycerides (MCT) and castor oil (CO), were investigated. The foaming experiments showed that both the type of cosurfactant, as well as the type of oil phase, affects the quality of the resulting foam. Emulsions that were based on a combination of hydrogenated lysophosphatidylcholine (hLPC) and a non-hydrogenated phospholipid, as well as LG as a cosurfactant and MCT as an oil phase, yielded the most satisfactory results. Furthermore, profile analysis tensiometry (PAT), polarization microscopy and laser diffraction analysis were used to characterize the developed formulations. These experiments suggest that the employed phospholipids predominantly stabilize the emulsions, while the cosurfactants are mainly responsible for the formation and stabilization of the foams. However, it appears that both sets of excipients are needed in order to acquire stable emulsions with satisfactory foaming properties.

Cationic surfactant-modified palygorskite particles as effective stabilizer for Pickering emulsion gel formation

Based on the synergistic interaction between palygorskite (PAL) and cetyltrimethylammonium bromide (CTAB), Pickering emulsion gel was successfully prepared in this study in a wide range of oil volume fraction (15–75%). All prepared emulsion gels remained stable for more than 6 months at room temperature. The microstructure, stability, and rheological properties of the prepared emulsion gels were characterized and evaluated. The influence of various environmental factors, including temperature, pH, salinity and types of oil phase on the formation of emulsion gels were investigated. A series of characterization methods were used to investigate the formation and stabilization mechanism of Pickering emulsion gel. The reduction of interfacial tension between oil and water, the changed surface characteristics of PAL, and the formation of a three-dimensional network structure in the continuous phase contributed to the stabilization of Pickering emulsion gel. This work presents a new strategy for the preparation of Pickering emulsion gel by using easily obtained clay particles.

Droplet Microfluidics with MALDI-MS Detection: The Effects of Oil Phases in GABA Analysis.

Microfluidic and mass spectrometry (MS) methods are widely used to sample and probe the chemical composition of biological systems to elucidate chemical correlates of their healthy and disease states. Though matrix-assisted laser desorption/ionization-mass spectrometry (MALDI)-MS has been hyphenated to droplet microfluidics for offline analyses, the effects of parameters related to droplet generation, such as the type of oil phase used, have been understudied. To characterize these effects, five different oil phases were tested in droplet microfluidics for producing samples for MALDI-MS analysis. Picoliter to nanoliter aqueous droplets containing 0.1 to 100 mM γ-aminobutyric acid (GABA) and inorganic salts were generated inside a polydimethylsiloxane microfluidic chip and deposited onto a conductive glass slide. Optical microscopy, Raman spectroscopy, and MALDI-mass spectrometry imaging (MSI) of the droplet samples and surrounding areas revealed patterns of solvent and oil evaporation and analyte deposition. Optical microscopy detected the presence of salt crystals in 50–100 μm diameter dried droplets, and Raman and MSI were used to correlate GABA signals to the visible droplet footprints. MALDI-MS analyses revealed that droplets prepared in the presence of octanol oil led to the poorest detectability of GABA, whereas the oil phases containing FC-40 provided the best detectability; GABA signal was localized to the footprint of 65 pL droplets with a limit of detection of 23 amol. The effect of the surfactant perfluorooctanol on analyte detection was also investigated.

Influence of the Oil Phase on the Wound Healing Activity of Sea Cucumber Extract-Based Cream Formulations

Sea cucumbers are attractive marine natural sources as they are enriched with functional biomaterials that can contribute in accelerating wound healing. The present study was carried out to prepare cream formulations comprising extract of sea cucumber with different type of oil phase, namely F1 (olive oil), F2 (tea tree oil) and F3 (lemongrass oil) to assess the influence of the oil on the physicochemical properties and the wound healing efficacy of the creams. The formulated creams showed satisfactory physicochemical characteristics such as homogeneity, spreadability, rheology, pH, and showed no evidence of phase separation even when the creams were kept at extreme conditions. The ex vivorelease profile of sea cucumber extract from the formulated creams was determined by using a Franz diffusion cells. F3 demonstrated a constant and yield the highest release percentage of sea cucumber extract, followed by F2 and F1. Topical application of the formulated creams on the excision wound in rats showed a significant wound healing efficacy compared to the control group. Among the creams formulation, F1 demonstrated a significantly higher rate of wound closure compared to F2, F3, and positive control. The wound healing efficacy of the formulated creams were not dependent on the ability of the oils in promoting skin permeation for the release of sea cucumber extract. This study depicted that lemongrass oil acted as a good skin permeation enhancer for the release of sea cucumber extract while olive oil worked in a more synergistic manner with sea cucumber extract in promoting wound healing.

Azacarbazole n-3 and n-6 polyunsaturated fatty acids ethyl esters nanoemulsion with enhanced efficacy against Plasmodium falciparum

Alternative therapies are necessary for the treatment of malaria due to emerging drug resistance. However, many promising antimalarial compounds have poor water solubility and suffer from the lack of suitable delivery systems, which seriously limits their activity. To address this problem, we synthesized a series of azacarbazoles that were evaluated for antimalarial activity against D10 (chloroquine-sensitive) and W2 (chloroquine-resistant) strains of P. falciparum. The most active compound, 9H-3-azacarbazole (3), was encapsulated in a novel o/w nanoemulsion consisting of ethyl esters of polyunsaturated fatty acids n-3 and n-6 obtained from flax oil as the oil phase, Smix (Tween 80 and Transcutol HP) and water. This formulation was further analyzed using transmission electron microscopy, dynamic light scattering and in vitro and in vivo studies. It was shown that droplets of the 3-loaded nanosystem were spherical, with satisfactory stability, without cytotoxicity towards fibroblasts and intestinal cell lines at concentrations corresponding to twice the IC50 for P. falciparum. Moreover, the nanoemulsion with this type of oil phase was internalized by Caco-2 cells. Additionally, pharmacokinetics demonstrated rapid absorption of compound 3 (tmax = 5.0 min) after intragastric administration of 3-encapsulated nanoemulsion at a dose of 0.02 mg/kg in mice, with penetration of compound 3 to deep compartments. The 3-encapsulated nanoemulsion was found to be 2.8 and 4.2 times more effective in inhibiting the D10 and W2 strains of the parasite, respectively, compared to non-encapsulated 3. Our findings support a role for novel o/w nanoemulsions as delivery vehicles for antimalarial drugs.

The phase behavior and solubilization ability of nonionic surfactant-distillate fraction of crude oil microemulsion system

In this paper, phase behavior in temperature scanning of E1305/distillate fractions/water/n-butyl alcohol microemulsion system were investigated. And the effect of surfactant concentration and oil type on microemulsion solubilization ability was studied. In the research, the content of saturates, aromatics, resins and asphaltenes in distillate fractions of crude oil was analyzed. The change of phase inversion temperature (PIT), solubilized ability and temperature caused by different compositions of distillate fraction was investigated. According to the experimental results, the phase behavior of temperature scanning was Winsor Ⅰ → Winsor Ⅲ → Winsor Ⅱ. The ability of solubilizing microemulsion was improved by increasing the surfactant content. The temperature of optimum solubilization was decreased with the increase of surfactant content. When the type of oil phase was changed, the solubilized ability of microemulsion was decreased with the increase of distillation temperature. And the optimum solubilization temperature was increased. According to the results, this phenomenon was caused by the increase of wax content and equivalent alkane carbon number.

Preparation of Carboxymethyl Cellulose-g- Poly(acrylamide)/Attapulgite Porous Monolith With an Eco-Friendly Pickering-MIPE Template for Ce(III) and Gd(III) Adsorption.

Due to their high specific surface and metal-binding functional groups in their crosslinked polymeric networks, monolithic materials incorporating a porous structure have been considered one of the most efficient kinds of adsorbents for rare earth element recovery. Herein, a facile and novel monolithic multi-porous carboxymethyl cellulose-g-poly(acrylamide)/attapulgite was synthesized by free radical polymerization via green vegetable oil-in-water Pickering medium internal phase emulsion (O/W Pickering-MIPEs), which was synergically stabilized by attapulgite and tween-20. The homogenizer rotation speed and time were investigated to form stable Pickering-MIPEs. The effects of different types of oil phase on the formation of Pickering-MIPEs were investigated with stability tests and rheological characterization. The structure and composition of the porous material when prepared with eight kinds of vegetable oil were characterized by FTIR and SEM. The results indicate that the obtained materials, which have abundant interconnected porosity, are comparable to those fabricated with Pickering-HIPE templates. The adsorption experiment demonstrated that the prepared materials have a fast capture rate and high adsorption capacities for Ce(III) and Gd(III), respectively. The saturation adsorption capacities for Ce(III) and Gd(III) are 205.48 and 216.73 mg/g, respectively, which can be reached within 30 min. Moreover, the monolithic materials exhibit excellent regeneration ability and reusability. This work provides a feasible and eco-friendly pathway for the construction of a multi-porous adsorbent for adsorption and separation applications.

Investigation of the formation mechanisms in high internal phase Pickering emulsions stabilized by cellulose nanocrystals.

Medium and high internal phase Pickering emulsions stabilized by cellulose nanocrystals (CNCs) have been prepared and the effects of CNC concentration and type of oil phase on the properties of emulsions were studied. The maximum oil phase volume that can be stabilized by CNCs is 87% when the CNC concentration is 0.6 wt.%; this slightly decreases to 83% when the CNC concentration is increased to 1.2 wt.% or higher. In addition, the oil droplets stabilized with 0.6 wt.% CNC suspensions have a larger size than those stabilized with higher concentration CNC suspensions. As evidenced by the change in oil droplet morphology and size, two different emulsion formation mechanisms are proposed. For a CNC concentration of 0.6 wt.%, the extra oil added into the emulsion is accommodated by the expansion of oil droplet size, whereas for CNC concentrations of 1.2 wt.% and higher, the oil is stabilized mainly by the formation of new oil droplets.

Development of microemulsions to reduce the viscocity of crude oil emulsions

The formation of water-in-oil (W/O) emulsions during extraction of petroleum is a major problem, because these emulsions increase the oil’s viscosity and thus significantly lower the production rates. In these situations, chemical products called emulsion viscosity reducers (EVRs) can be injected during crude oil production. The development of EVRs consisting of oil-in-water (O/W) microemulsions can attract a good deal of attention due to the possibility of reducing costs and increasing environmental friendliness (they are mostly composed of water instead of large volumes of organic solvents). This article describes the preparation of O/W microemulsions, using the solvents kerosene, Solbrax or xylene as components of the oil phase and three commercial nonionic polymer surfactants based on poly(ethylene oxide) as the aqueous phase. For this purpose, first ternary phase diagrams (water/oil/surfactant) were constructed to determine the optimal concentrations of these components to prepare the O/W microemulsions, selecting 16wt% surfactant, 4wt% oil phase and 80wt% aqueous phase as the common composition of all the systems studied. The efficiency of the microemulsion systems was investigated by rheological tests in synthetic water/oil emulsions prepared from a heavy crude oil (°API 20). The microemulsion systems were tested regarding their interfacial activity by analyzing the interfacial tension and the average size of the water droplets dispersed in the crude oil, before and after adding the systems developed. The results showed that the performance of the O/W microemulsions did not depend on the type of oil phase, but that the insertion of an oil phase (i.e., the formation of an O/W microemulsion) improved the performance of the surfactant in the medium compared to the efficiency of the aqueous surfactant solutions.

Preparation and Evaluation of Physical and, Rheological Properties of Clotrimazole Emulgel

Recently, emulgel has emerged as one of the most interesting topical preparations in the field of pharmaceutics. In this research clotrimazole was formulated as topically applied emulgel ; different formulas were prepared. The prepared emulgels were evaluated for their physical appearance , rheological behaviour , and in vitro drug release . The influence of the type of gelling agent (carbopol 934 and methyl cellulose), the concentration of both the emulsifying agent (2% and 4% w/w of mixture of span 20 and tween 20) and the oil phase (5% and 7.5% w/w of liquid paraffin) and the type of oil phase (liquid paraffin and cetyl alcohol), on the drug release from the prepared emulgels was investigated. Commercially available topical canestin® cream was used for comparison. All the prepared emulgels showed acceptable physical properties concerning colour, homogeneity, consistency, and pH value. Rheological studies revealed that all emulgels formulations exhibited a shear – thinning behaviour with thixotropy, indicating structural break down of intermolecular interaction between polymeric chains. Clotrimazole emulgels exhibited higher drug release than canestin® cream. The results of in vitro release showed that methyl cellulose – based emulgel gave better release than carbopol 934 – based one. Also it was found that the emulsifying agent concentration had the most pronounced effect on the drug release from the emulgels, followed by the oil phase concentration, which has a retardation effect, and finally the type of the gelling agent. It was suggested that the clotrimazole emulgel formulation prepared with methyl cellulose, with low concentration of oil phase (5%w/w liquid paraffin) and high concentration of emulsifying agent (4%w/w), showed an optimum formula for highest drug release (74.4% after three hours), which followed higuchi diffusion model with a diffusion-controlled mechanism. 
 Key words: Emulgel , carbopol , methyl cellulose , clotrimazole 

Beeswax organogels: Influence of gelator concentration and oil type in the gelation process

This work focused on how different types of oil phase, MCT (medium chain triglycerides) and LCT (long chain triglycerides), exert influence on the gelation process of beeswax and thus properties of the organogel produced thereof. Organogels were produced at different temperatures and qualitative phase diagrams were constructed to identify and classify the type of structure formed at various compositions. The microstructure of gelator crystals was studied by polarized light microscopy. Melting and crystallization were characterized by differential scanning calorimetry and rheology (flow and small amplitude oscillatory measurements) to understand organogels' behaviour under different mechanical and thermal conditions. Fourier transform infrared spectroscopy (FTIR) analysis was employed for a further understanding of oil-gelator chemical interactions. Results showed that the increase of beeswax concentration led to higher values of storage and loss moduli (G′, G″) and complex modulus (G*) of organogels, which is associated to the strong network formed between the crystalline gelator structure and the oil phase. Crystallization occurred in two steps (well evidenced for higher concentrations of gelator) during temperature decreasing. Thermal analysis showed the occurrence of hysteresis between melting and crystallization. Small angle X-ray scattering (SAXS) analysis allowed a better understanding in terms of how crystal conformations were disposed for each type of organogel. The structuring process supported by medium or long-chain triglycerides oils was an important exploit to apprehend the impact of different carbon chain-size on the gelation process and on gels' properties.

Bromelain Encapsulated in Self Assembly Nanoemulsion Exhibits Better Debridement Effect in Animal Model of Burned Skin

Bromelain is a mixture of proteolytic enzymes presence in all tissues of pineapple (Ananas comosus). It is known for clinical use as debridement for burn treatment. However, it is easily degraded by light, high temperature and pH. Nanoemulsion of bromelain is promising to increase its stability. In this study, we investigated the nanoemulsion of bromelain and its formulation into gel preparation in order to increase its efficacy for the burn treatment. Spontaneous or self-nanoemulsifying was applied to form nanoemulsion of bromelain (NEB). Bromelain was incorporated in various types of oil phase i.e virgin coconut oil (VCO), olive oil, vitamin E acetate and combination of both vitamin E acetate and VCO. Cremophor RH 40 was used together with polyethyleneglycol 400 to reduce oil-water interface tension. The stability of NEB in different oil phases was evaluated including particle size, polydispersity index, zeta potential, enzymatic activity and nanoemulsion morphology. Further, the most stable NEB was incorporated into hydrophilic gel matrix. An in vivo evaluation was carried out in hot plate-induced burn skin of New Zealand rabbit. Treatment of wounds was given by applying the preparations: NEB and the nanoemulsion bromelain-CMC gel (GKNB), using a standard protocol. As a control, untreated rabbit burned skin was provided. The efficacy of NEB was evaluated by observing wound contraction, eschar score, erythemic score, pus score and edema. After 14 days of storage, nanoemulsion using vitamin E acetate was found to be the most appropriate formula to encapsulate bromelain with good physical and chemical stabilities. This formula shows clear visual appearance with globule diameter of 74.37 nm, narrow size distribution, high loading efficiency of 97.96 %, and ability to maintain the enzymatic activity of bromelain compared to gel preparation using corresponding bromelain nanoemulsion. The vitamin E acetate nanoemulsion system shows better reduction in wound contraction until the 14th day of observation as well as other relevant parameters for wound healing effects. Taken together, bromelain formulated with the vitamin E acetate nanoemulsion improved the stability of bromelain and showed better activity to heal burnt skin on the animal model tested. The gel matrix retained the release of bromelain resulting in lower wound healing effect but it may have prolonged activity.

Study of Pickering emulsion stabilized by sulfonated cellulose nanowhiskers extracted from sisal fiber

Sulfonated cellulose nanowhiskers (sulfonated CNWs), a kind of needle-like colloidal particles, could be obtained through sulfuric acid hydrolysis of microcrystal cellulose extracted from sisal fibers. Here, stable Pickering emulsions were prepared using the sulfonated CNWs as a stabilizer. The effects of the sulfonated CNW concentration in aqueous phase, volume ratio of water to oil, oil type, and the pH value on the stability, type, and morphology of these emulsions were investigated. The average droplet size decreases with increasing sulfonated CNW concentration and volume ratio of water to oil. Many types of oil phase were stabilized by sulfonated CNWs to form stable oil-in-water (o/w) Pickering emulsion only by adjusting the pH value of water phase. In addition, poly(methyl methacrylate)PMMA/sulfnated CNW composite microspheres were fabricated by solvent volatilization of the as-prepared Pickering emulsion. Confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) studies confirmed that sulfonated CNWs adsorbed on the surface of the PMMA microparticles. With the interesting renewability and biodegradability of the sulfonated cellulose nanowhisker, these PMMA@sulfonated CNW composite microsphere could find great potential application in food, cosmetics, drug delivery, and biological tissue engineering, etc.

High accuracy NMR chemical shift corrected for bulk magnetization as a tool for structural elucidation of microemulsions. Part 2 – Anionic and nonionic dilutable microemulsions

In our previous report we suggested a new analytical tool, high accuracy NMR chemical shift corrected for bulk magnetization as a supplementary tool to study structural transitions and droplet size and shape of dilutable microemulsions. The aim of this study was to show the generality of this technique and to demonstrate that in almost any type of microemulsion this technique provides additional valuable structural information. The analysis made by the technique adds to the elucidation of some structural aspects that could not be clearly determined by other classical techniques.Therefore, in this part we are extending the study to three additional systems differing in the type of oil phase (toluene and cyclohexane), the nature of the surfactants (anionic and nonionic), and other microemulsion characteristics.We studied sodium dodecyl sulfate (SDS)-based anionic microemulsions with different oils and a nonionic microemulsion based on Tween 20 as the surfactant and toluene as the oil phase. All the microemulsions were fully dilutable with water.We found that the change in the slope of chemical shift against dilution reflects phase transition points of the microemulsion (O/W, bicontinuous, W/O). Chemical shift changes were clearly observed with the transition between spherical and non-spherical (wormlike, etc.) droplet shapes. We compared the interaction of cyclohexane and toluene and used the anisotropic effect of toluene’s ring current to determine its preferred orientation relative to SDS.Chemical shifts of the microemulsion components are therefore a useful addition to the arsenal of techniques for characterizing microemulsions.

Organogel-Emulsions with Mixtures of β-Sitosterol and γ-Oryzanol: Influence of Water Activity and Type of Oil Phase on Gelling Capability

In this study, water-in-oil emulsions were prepared from water containing different salt concentrations dispersed in an oil phase containing a mixture of β-sitosterol and γ-oryzanol. In pure oil, the β-sitosterol and γ-oryzanol molecules self-assemble into tubular microstructures to produce a firm organogel. However, in the emulsion, the water molecules bind to the β-sitosterol molecules, forming monohydrate crystals that hinder the formation of the tubules and resulting in a weaker emulsion-gel. Addition of salt to the water phase decreases the water activity, thereby suppressing the formation of sitosterol monohydrate crystals even after prolonged storage times (∼1 year). When the emulsions were prepared with less polar oils, the tubular microstructure was promoted, which significantly increased the firmness of the emulsion-gel. The main conclusion of this study is that the formation of oryzanol and sitosterol tubular microstructure in the emulsion can be promoted by reducing the water activity and/or by using oils of low polarity.

The rheology of some oil-in-water emulsions stabilized by condensed complex films

Abstract The rheology of emulsions containing oleyl, lauryl or cetostearyl alcohol as the oil-soluble component has been examined. As the concentration of fatty alcohol was increased, three main types of behaviour were found. These could not be explained by the particle size distribution, phase weight ratio or internal phase viscosity. It is suggested that migration of oil-soluble component and subsequent formation of viscous gels in the aqueous phase accounted for the observed behaviour. The effects of temperature, type of oil phase and chemical constitution of water-soluble components, have also been examined.

Sample stacking for the analysis of catechins by microemulsion EKC

In this study, an on-line concentration method, ASEI (anion-selective exhaustive injection)-sweeping technology which was coupled with microemulsion EKC (MEEKC), was used to analyze and detect six catechins ((-)-epicatechin, (+)-catechin, (-)-epigallocatechin gallate, (-)-epicatechin gallate, (-)-epigallocatechin, and (-)-gallocatechin). In addition to the effects of the buffer pH and electrolyte concentration on stacking, the compositions of microemulsion (types of oil phase, and types and levels of cosurfactant) also dominated the stacking effect of catechins. In MEEKC, the effect of the type of oil in microemulsion on separation mechanism is often unclear. This study had demonstrated that the oil type in microemulsion indeed altered the affinity of oil droplets with analytes. Finally, this proposed ASEI-sweeping MEEKC method was able to detect trace level of catechins in food products that was not previously possible by a normal MEEKC method.