Phase Separation Of Emulsions Research Articles

Functionality of chemical additives and experimental conditions during formation of acid-induced emulsion and sludge

Petroleum has still maintained its position among energy sources, and there is a considerable demand for its higher production. A viable process that could improve oil production is acid stimulation. In this process though, acid-induced emulsion and sludge formation may profoundly compromise its performance. This study concentrates on experimental evaluation of these drawbacks considering the influence of several chemical additives that are usually used in acid stimulation including corrosion inhibitor, corrosion inhibitor intensifier, suspending, and iron control agents. In addition, the effect of operating conditions such as the volumetric ratio of acid and crude oil, mixing shear, ferric ions concentration, and various acid systems were studied during emulsion phase separation and sludge formation. Acid systems including HCl 15 and 28 wt% solutions, spent HCl, hybrid (a mixture of HCl and acetic acid), and emulsified acids (HCl in diesel) were also investigated. The results confirmed that although the additives are necessary for their main functionalities, nonetheless, they postponed the emulsion phase separation for at least 30 min. They also showed only meagre impact on the amount of formed sludge (<1 %), and a meaningful relationship could not be established between their presence and sludge formation. The acid phase volumetric ratio had an inverse impact on emulsion stability in such a way that 10 times more emulsion break happened by increasing the volumetric ratio from 0.25 to 0.75. Unlike previous studies, ferric ions formed less stable emulsions due to the presence of corrosion inhibitor and iron control agents. However, they were not able to control sludge formation. In addition, hybrid and emulsified acids showed high acid-crude oil emulsion stability for all samples along with higher amounts of sludge. Finally, spent acid showed less affinity to form sludge and emulsion.

Encapsulated phenolic compounds: clinical efficacy of a novel delivery method

AbstractEncapsulation is a drug or food ingredient loaded-delivery system that entraps active components, protecting them from decomposition/degradation throughout the processing and storage stages and facilitates their delivery to the target tissue/organ, improving their bioactivities. The application of this technology is expanding gradually from pharmaceuticals to the food industry, since dietary bioactive ingredients, including polyphenols, are susceptible to environmental and/or gastrointestinal conditions. Polyphenols are the largest group of plants' secondary metabolites, with a wide range of biological effects. Literature data have indicated their potential in the prevention of several disorders and pathologies, ranging from simpler allergic conditions to more complex metabolic syndrome and cardiovascular and neurodegenerative diseases. Despite the promising health effects in preclinical studies, the clinical use of dietary polyphenols is still very limited due to their low bioaccessibility and/or bioavailability. Encapsulation can be successfully employed in the development of polyphenol-based functional foods, which may improve their bioaccessibility and/or bioavailability. Moreover, encapsulation can also aid in the targeted delivery of polyphenols and may prevent any possible adverse events. For the encapsulation of bioactive ingredients, several techniques are applied such as emulsion phase separation, emulsification/internal gelation, film formation, spray drying, spray-bed-drying, fluid-bed coating, spray-chilling, spray-cooling, and melt injection. The present review aims to throw light on the existing literature highlighting the possibility and clinical benefits of encapsulated polyphenols in health and disease. However, the clinical data is still very scarce and randomized clinical trials are needed before any conclusion is drawn. Graphical abstract

Sodium alginate/epoxy resin was separated by emulsion phase to fabricate a strong superhydrophobic coating

It has been recognized that good mechanical robustness and chemical stability are the keys to superhydrophobic coatings. Here, we used epoxy resin/sodium alginate emulsion phase separation method to prepare the coating body, and polydimethylsiloxane/vapor phase silicon dioxide as the superhydrophobic material to prepare a superhydrophobic silicon dioxide coating. Sodium alginate is enriched on the coating surface by phase separation process, which greatly improves the interaction force between the superhydrophobic material and the coating body. The water contact angle of the EP/SA/SiO2 superhydrophobic coating is 157.6° and the sliding angle is 2.3° The EP/SA/SiO2 superhydrophobic coating has good mechanical robustness, chemical stability and self-cleaning performance. Thanks to the micro-nano structure of the surface Cassie-Baxter model, air can be trapped on the solid-liquid contact surface of the coating. The impedance value of the EP/SA/SiO2 coating is two orders of magnitude higher than that of the epoxy coating, which has excellent anti-corrosion properties. It is believed that this study can provide a new idea for preparing strong superhydrophobic coatings.

Chitosan/polydopamine/octacalcium phosphate composite microcarrier simulates natural bone components to induce osteogenic differentiation of stem cells

Natural polymers and minerals can be combined to simulate natural bone for repairing bone defects. However, bone defects are often irregular and pose challenges for their repair. To overcome these challenges, we prepared Chitosan/Polydopamine/Octacalcium phosphate (CS/PDA/OCP) microcarriers that mimic bone composition and micro-size to adapt to different bone defect defects. CS/PDA microspheres were prepared by emulsion phase separation method and PDA in-situ polymerization. Finally, it was used to adsorb and immobilize OCP particles, resulting in the preparation of CS/PDA/OCP composite microcarriers. The microcarriers maintain an interconnected porous structure and appropriate porosity, which promotes cell adhesion, proliferation, and nutrient exchange. Subsequently, the protein adsorption capacity, simulated degradation, cell adhesion and proliferation capacity of the composite microcarriers were investigated. Additionally, their ability to simulate mineralization and induce osteogenic differentiation of BMSCs was characterized. The results demonstrated that the composite microcarrier had good biocompatibility and was conducive to cell adhesion and proliferation. Moreover, ALP and ARS staining revealed that the addition of OCP significantly enhanced the osteogenic differentiation of BMSCs. These results indicate that the composite microcarrier has promising prospects for bone repair applications.

Water-in-water emulsion stabilized by cellulose nanocrystals and their high enrichment effect on probiotic bacteria

HypothesisThe effect of the molecular weight and polymer concentration on the partition behavior of aqueous two-phase systems (ATPs) is significant for constructing water-in-water (W/W) emulsions. Hence, a long-term stable W/W emulsion system might be obtained through selecting the appropriate stabilizer and component phases, which could be a possible carrier for probiotics. ExperimentsCompared with the reported molecular weight difference between polyethylene oxide (PEO) and dextran (DEX) systems, PEO and dextran with lower molecular weight had been used for constructing the water in water (W/W) emulsion system. The W/W emulsions were stabilized using cellulose nanocrystals (CNCs), and the potential application of the W/W emulsion for the encapsulation of Lactobacillus was explored. FindingsEmulsion stability exhibited a “dose-effect” relationship with the CNCs concentration and was decreased with the increase of the DEX concentration. The emulsion phase separation rate was increased with increasing ionic strength and temperature. Both Lactobacillus Plantarum and Lactobacillus helveticus were highly inclined to the DEX phase, and the emulsion droplets were deformed and aggregated when the encapsulation amount was increased. This long-term stability would provide a promising approach for designing high-density culture and fermentation of probiotics.

PH-dependent micellar properties of edible biosurfactant steviol glycosides and their oil-water interfacial interactions with soy proteins

The natural sweetener steviol glycosides (STE) have been shown to be an effective biosurfactant for formulation of food emulsions. In this work, we first investigated the impact of pH on the micellar self-assembly of STE, and then evaluated the interfacial and macroscopic emulsion properties of the mixtures of STE with soy protein isolate (SPI) at different pH values (3.0 and 7.0). The results obtained show that as an edible bolaform surfactant, STE is a highly pH-sensitive system, showing interesting pH-dependent interfacial and emulsifying behaviors, which are found to strongly affect its oil-water interfacial interactions with SPI as well as the emulsion properties of the STE-SPI mixtures. Particularly, at low STE concentrations (0.1–0.4 wt%, below critical micelle concentration (CMC)), the adsorption kinetics of mixtures at pH 7.0 is mainly dominated by the STE-SPI complex, forming the interface with a plateau in the elasticity. In contrast, at pH 3.0, the simultaneous adsorption of STE and the STE-SPI complex dominates the formation of interface, resulting in a lower initial interfacial tension and a less viscoelastic film. These interfacial behaviors endow the emulsions prepared by the mixtures with an improved emulsifying ability. On the other hand, at high STE concentrations (0.8 and 1 wt%, above CMC), for the mixtures at pH 7.0, the preferential interfacial adsorption of STE over the complex leads to the formation of a simple interface mainly covered by STE. Contrastly, the interfaces at pH 3.0 are still complex and dominated simultaneously by STE and STE-SPI complex. However, the poor emulsifying capacity of STE at pH 3.0 greatly disturbs the emulsifying properties of the mixtures, resulting in the large oil droplets and the consequent phase separation of emulsions.

Formation development and evaluation of microsphere of sulfasalazine for the treatment inflammatory bowel diseases

Inflammatory bowel disease (IBD) is a chronic relapsing and remitting inflammatory disorder of the small intestine and colon. IBD includes ulcerative colitis (UC) and Crohn’s disease (CD), and it is a main reason for the expansion of colon cancer, referred to as colitis-associated cancer (CAC). Oral colon-targeted microsphere based drug delivery system containing sulfasalazine was prepared, optimized and characterized. The microspheres were effectively prepared by simple emulsification phase-separation technique followed by cross-linking. The formulations were optimized on the basis of drug: polymer ratio, stirring speed, concentration of glutaraldehyde. The prepared microspheres were characterized on the basis of morphology, entrapment efficiency, particle size and in-vitro release.&#x0D; Keywords: Microspheres, Sulfasalazine, Inflammatory bowel disease, Colon-targeted, Chitosan

Polylysine-decorated macroporous microcarriers laden with adipose-derived stem cells promote nerve regeneration in vivo

Cell transplantation is an effective strategy to improve the repair effect of nerve guide conduits (NGCs). However, problems such as low loading efficiency and cell anoikis undermine the outcomes. Microcarriers are efficient 3D cell culture scaffolds, which can also prevent cell anoikis by providing substrate for adhesion during transplantation. Here, we demonstrate for the first time microcarrier-based cell transplantation in peripheral nerve repair. We first prepared macroporous chitosan microcarriers (CSMCs) by the emulsion-phase separation method, and then decorated the CSMCs with polylysine (pl-CSMCs) to improve cell affinity. We then loaded the pl-CSMCs with adipose-derived stem cells (ADSCs) and injected them into electrospun polycaprolactone/chitosan NGCs to repair rat sciatic nerve defects. The ADSCs-laden pl-CSMCs effectively improved nerve regeneration as demonstrated by evaluation of histology, motor function recovery, electrophysiology, and gastrocnemius recovery. With efficient cell transplantation, convenient operation, and the multiple merits of ADSCs, the ADSCs-laden pl-CSMCs hold good potential in peripheral nerve repair.

CO2 switchable deep eutectic solvents for reversible emulsion phase separation.

The concept of CO2 switchable deep eutectic solvents (DESs) was proposed and a series of CO2 switchable imidazole-based deep eutectic solvents (DESs) was designed. The CO2 switch mechanism was investigated and the system was used for easy emulsion separation of olive oil from DESs. The benign CO2 switchable DESs have great potential applications in dissolution and easy separation.

Influence of formulation on physical stability of cherry (Muntingia calabura L.) leaves extract as an antibacterial

Cherry leaves have been known as an antibacterial and a natural antiseptic that contain flavonoids, saponins and tannins. This research aims to prepare two formulation of cherry leaves extract and to evaluate their physical stability as an antibacterial dosage form. cherry leaves were extracted using ethanol 96% by maceration method. The extract was formulated as a hydrogel with carbomer and a water-based cream with combination of stearic acid and TEA. Physical stability was determined at cool temperature (4°C) and room temperature (± 25°C) by organoleptic, pH, homogeneity, spread, and emulsion type test (for water-based cream). The results showed that all formula of hydrogel was stable in organoleptic, homogeneity and spread test, but the pH value was on 9 which is higher than normal skin pH. Otherwise, the water-based cream was stable in organoleptic, pH and spread test, but in formula 1 showed an emulsion phase separation and formula 3 showed a non-homogeneous arrangement and visible grain after 14 days of storage. Both of the preparation was suitable to applicate cherry leaves extract in antibacterial dosage form with data of skin irritation test.

Stability of pH-responsive Pickering emulsion stabilized by carboxymethyl starch/xanthan gum combinations

The objective of this study was to investigate the effect of different pH values (3, 5, 7, 9 and 11) on the stability of Pickering emulsions stabilized by carboxymethyl starch (CMS)/xanthan gum (XG) combinations. The CMS/XG combinations could be used as an effective stabilizer for the preparation of Pickering emulsion. The effects of CMS/XG combinations on oil droplet size, Zeta potential, rheological properties, backscattering profiles, Low-field nuclear magnetic resonance imaging and storage stability of oil-in-water emulsion were evaluated as a function of pH. As pH increased from 3 to 11, the droplet size of the emulsion increased and the absolute value of Zeta potential decreased. Besides, the consistency coefficient of the emulsion was reduced and the pseudoplasticity was weakened. The variation of backscattered light intensity of the emulsion at pH 3 was the smallest. The combination of CMS and XG formed a good network structure and inhibited the phase separation of emulsion. The color distribution of Low-field nuclear magnetic resonance imaging of emulsions at pH 3, 5 and 7 was more uniform and had better storage stability at 25 °C for 9 days. pH affected the aggregation of oil droplets. The Pickering emulsion stabilized by CMS/XG combinations was pH-responsive and could be used as an effective carrier for biologically active substances.

Factors Affecting the Stability and Physical Properties of Pickering Emulsions Stabilized by Fe3 O4 @CNC Nanocomposites

Particle-stabilized emulsion systems, namely Pickering emulsions have recently emerged as novel yet attractive dosage form for controlled delivery of biologically active compounds. The stability and properties of emulsions are influenced by formulation and processing factors. In this study, oil-in-water Pickering emulsions were prepared using Fe3 O4 @cellulose nanocrystal (MCNC) nanocomposites and the effects of CNC/Fe3 O4 (CNC/MNP) ratios, MCNC particle concentration Cmcnc, oil volume fraction φoil and ionic strength on the colloidal stability were evaluated. The results showed that stable emulsions could be attained using MCNC particles with CNC/MNP ratio ≤ 1. Increasing CNC/MNP ratio &gt; 1 resulted in different degree of phase separation of emulsions. The average droplet size of MCNC-stabilized Pickering emulsions (MCNC-PE) decreased from 17.34 to 3.58 µm with an increase in Cmcnc as a result of improved coalescence stability due to higher droplet surface coverage Smcnc by MCNC particles. An increase in φoil led to pronounced increase in droplet size from 2.82 to 17.00 µm. Interestingly, the ionic strength showed little or no impact on the emulsion droplet size and creaming. The storage stability study revealed that most emulsions remained fairly stable with no apparent change in droplet size. In conclusion, the physical stability of MCNC-PE was found to be greatly influenced by particulate emulsifier concentration and oil loadings. These two parameters must be well controlled in the development of Pickering emulsions for potential food and pharmaceutical applications.

Ionic Liquid-Based Microemulsions with Reversible Microstructures Regulated by CO2.

CO2-responsive microemulsions based on ionic liquid 1,1,3,3-tetramethylguanidine-oleic acid (TMG-OA) have been designed to provide an approach for reducing the volatilization of amine in amine-containing microemulsions effectively and exhibit reversible transitions of microstructures. The ionic liquid TMG-OA was prepared by the direct neutralization of oleic acid (HOA) and 1,1,3,3-tetramethylguanidine (TMG, one of volatile and toxic amines). From the investigations of nuclear magnetic resonance hydrogen spectrum, pH, thermogravimetry, and automatic interface tension meter, the excellent properties of switchability, stability, and surface activity of TMG-OA were demonstrated, and then the ionic liquid-based microemulsions with CO2 response were prepared with TMG-OA (surfactant), HOA (oil phase), isopropyl alcohol (IPA, cosurfactant), and water. Interestingly, for microemulsions with a higher IPA content (47.42, 44.48 wt %), sizes of microemulsions are increased upon introducing CO2 and decreased upon addition of N2/65 °C. In addition, for microemulsions with a lower IPA content (26.22 wt %), the new microemulsions with different sizes are regenerated after the phase separation of emulsions generated by introducing CO2, and incomplete recovery of microemulsions can be observed upon addition of N2/65 °C. The reversible microstructures are induced by the swelling behavior and the reduced single phase area, which are caused by the reversible conversion between TMG-OA and HOA components.

Multidimensional Design of Anisotropic Polymer Particles from Solvent‐Evaporative Emulsion

AbstractColloidal particles with controlled shape and internal structure have attracted great attention due to their novel morphologies and various potential applications. Among the diverse synthetic strategies toward anisotropically shaped polymer particles, facile and accurate engineering of such structures remains challenging. This review highlights the synthetic approaches to manipulate the shape of polymer particles driven by phase separation in emulsions upon solvent evaporation. And, special attention is given to the thermodynamic and kinetic principles of particle shape control, followed by detailed experimental examples and their applications. Major synthetic strategies for the preparation of nonspherical block copolymer (BCP) particles by evaporation of solvent from BCP‐containing emulsions are discussed as follows: engineering of i) interfacial properties of the confining emulsion droplets, ii) particle (or droplet) size, iii) segregation behavior of BCPs within the droplet, and iv) solvent‐induced BCP self‐assembly kinetics (i.e., solvent evaporation rate). Next, functionalized BCP particles produced by careful design of the chemical structures of polymer or by incorporation of functional additives into the polymer matrix are introduced. Finally, this review article aims to present the challenging issues associated with current methods and future directions for research in this field.

Preparation and evaluation of injectable Rasagiline mesylate dual-controlled drug delivery system for the treatment of Parkinson’s disease

A microsphere–gel in situ forming implant (MS–Gel ISFI) dual-controlled drug delivery system was applied to a high water-soluble small-molecule compound Rasagiline mesylate (RM) for effective treatment of Parkinson’s disease. This injectable complex depot system combined an in situ phase transition gel with high drug-loading and encapsulation efficiency RM–MS prepared by a modified emulsion-phase separation method and optimized by Box–Behnken design. It was evaluated for in vitro drug release, in vivo pharmacokinetics, and in vivo pharmacodynamics. We found that the RM-MS-Gel ISFI system showed no initial burst release and had a long period of in vitro drug release (60 days). An in vivo pharmacokinetic study indicated a significant reduction (p < .01) in the initial high plasma drug concentration of the RM–MS–Gel ISFI system compared to that of the single RM–MS and RM–in situ gel systems after intramuscular injection to rats. A pharmacodynamic study demonstrated a significant reduction (p < .05) in 6-hydroxydopamine-induced contralateral rotation behavior and an effective improvement (p < .05) in dopamine levels in the striatum of the lesioned side after 28 days in animals treated with the RM–MS–Gel ISFI compared with that of animals treated with saline. MS-embedded in situ phase transition gel is superior for use as a biodegradable and injectable sustained drug delivery system with a low initial burst and long period of drug release for highly hydrophilic small molecule drugs.

Interfacial properties of green leaf cellulosic particles

Cellulosic pulp from sugar beet leaves was fractionated and assessed on its interfacial properties. After pressing leaves to express the juice, the press cake was washed at alkaline pH (pH 9) to remove residual protein, dried, milled and air classified. The obtained cellulosic particles mainly consisted of insoluble dietary fibre (77.8% w/w) with remaining proteins (6.3% w/w) and exhibited considerable interfacial activity. The protein impurities contribute to the surface charge of the particles and provide surface activity, leading to spontaneous diffusion of the particles during the interfacial tension analysis; whereas the particle adsorption kinetics were characteristic of soft particles or Pickering emulsifiers. The interfacial rheology measurements showed abnormal behaviour and unusual drop shape upon deformation, hindering interpretation of the analysis but still suggesting a rigid interface with strong physical particle-particle interactions. Stable oil-in-water emulsions were produced using cellulosic particles, and despite phase separation, the emulsions were stable against coalescence. The results suggested that mostly fine particles (0.04–1.0 μm) were responsible for the interfacial stabilisation, given the small oil droplets obtained (2–5 μm); whereas larger particles (>10 μm) created a network in the continuous phase, which was responsible for the emulsion phase separation. It was concluded that the cellulosic particles had a soft nature and suitable shape to produce stable Pickering emulsions, which can be used as food-grade particles for food and pharma applications.

Emulsions stabilized by high acyl gellan and KCl

Emulsions containing high acyl gellan (0.025 or 0.100% w/w) as emulsifier/stabilizer with KCl addition (1.6–15,633mg of KCl/g of gellan) were evaluated. In general a decrease in apparent viscosity and an increase of the droplets size were observed as KCl content rises. Addition of intermediate KCl concentration (62.6–1,563mg of KCl/g of gellan) could improve the stability to macroscopic phase separation of emulsions with the lower gellan concentration (0.025% w/w). However it was observed that KCl content above a critical value (1,563mg of KCl/g of gellan) caused the breakup of the emulsions containing 0.025% or 0.10% w/w of gellan, showing that emulsions properties could be easily modulated by the salt-polysaccharide ratio, allowing the formation of emulsions for different purposes. High viscosity of the continuous medium and the repulsive forces of the charged droplets were the main emulsions stabilizing mechanisms. However the formation of a physical barrier on droplets interface by deposition of gellan aggregates could be occurring at particular conditions of KCl-gellan ratio.

Stability and Oil Migration of Oil-in-Water Emulsions Emulsified by Phase-Separating Biopolymer Mixtures.

Oil-in-water (O/W) emulsions with varying concentration of oil phase, medium-chain triglyceride (MCT), were prepared using phase-separating gum arabic (GA)/sugar beet pectin (SBP) mixture as an emulsifier. Stability of the emulsions including emulsion phase separation, droplet size change, and oil migration were investigated by means of visual observation, droplet size analysis, oil partition analysis, backscattering of light, and interfacial tension measurement. It was found that in the emulsions prepared with 4.0% GA/1.0% SBP, when the concentration of MCT was greater than 2.0%, emulsion phase separation was not observed and the emulsions were stable with droplet size unchanged during storage. This result proves the emulsification ability of phase-separating biopolymer mixtures and their potential usage as emulsifiers to prepare O/W emulsion. However, when the concentration of MCT was equal or less than 2.0%, emulsion phase separation occurred after preparation resulting in an upper SBP-rich phase and a lower GA-rich phase. The droplet size increased in the upper phase whereas decreased slightly in the lower phase with time, compared to the freshly prepared emulsions. During storage, the oil droplets exhibited a complex migration process: first moving to the SBP-rich phase, then to the GA-rich phase and finally gathering at the interface between the two phases. The mechanisms of the emulsion stability and oil migration in the phase-separated emulsions were discussed.

Combined effects of milk fat globule membrane polar lipids and protein concentrate on the stability of oil-in-water emulsions

Milk fat globule membrane (MFGM) material isolated from reconstituted buttermilk by microfiltration (i.e., whole MFGM) contains two major fractions, namely proteins (consisting mainly of MFGM-specific proteins and serum proteins) and lipids (original membrane polar lipids and contaminating triglycerides from the globule core). In this study, MFGM proteins and polar lipid (PL) concentrate were separated from whole MFGM material using solvent extraction. The particle size distribution, stability, surface protein and polar lipid load of oil-in-water emulsions prepared with protein or PL concentrate, individually or in combination, at various concentrations were examined. At low emulsifier concentrations (<2.3%), there was an interacting effect between proteins and PLs on the droplet size. The phase separation of emulsions prepared with a combination of 0.3% proteins and 0.3% PLs was similar to that of emulsions containing 0.3% proteins. The proteins were more preferentially adsorbed at the emulsion droplet surface compared with PLs.

Emulsifying Properties of Sericin Obtained from Hot Water Degumming Process

AbstractSericin is a protein present in the silkworm cocoon of Bombyx mori. Although usually discarded during the silk degumming process, which causes environmental impact and high costs of wastewater treatment, this protein possesses properties that are particularly useful to the food industry. This work was carried out to determine the amino acid profile and evaluate the antioxidant and emulsifier capacity of sericin. The main amino acids present in sericin are glycine, serine and aspartic acid. The high‐molecular‐weight fractions of this protein have antioxidant activity. Furthermore, due to the predominant hydrophilic character of its amino acids, it acts as an emulsifier. The emulsions prepared with 1.0% of sericin were stable for 24 h. All emulsions showed pseudoplastic behavior and great internal strength, according to the rheological analysis. Thus, sericin can be used as an additive in emulsified products providing antioxidant properties in these products.Practical ApplicationsThe present work provides an application as emulsifier to sericin, which is normally discarded during the silk process. This protein prevents phase separation in emulsions and provides antioxidant activity to the formed emulsion, besides being a natural product. The resulting emulsions prepared with high concentration of sericin have high viscosity, and therefore sericin can be used in the production of mayonnaise and creams. It can also be used, in lower concentrations, in salad dressing for example, resulting in a lower viscosity product.