Crocin loaded nano-emulsions: Factors affecting emulsion properties in spontaneous emulsification

Therapeutic potential of limonene-based syringic acid nanoemulsion: Enhanced ex-vivo cutaneous deposition and clinical anti-psoriatic efficacy

Nanoemulsions have carved their position in topical delivery owing to their peculiar features of forming a uniform film on the skin and conquering stratum corneum barrier and hence fostering dermal penetration and retention. The present work developed syringic acid nanoemulsion (SA-NE) by spontaneous emulsification as an anti-psoriatic remedy via the dermal route. SA-NE were prepared with either lauroglycol90, limonene or their combination (oil phase) and tween80 (surfactant) with variable concentrations. The physicochemical characteristics of SA-NE were assessed together with Ex-vivo skin deposition and dermal toxicity. The effectiveness of optimal formula in psoriatic animal model and psoriatic patients was investigated using PASI scoring and dermoscope examination. Results showed that, SA-NE containing mixture of lauroglycol 90, limonene and 10 % tween80 (F5), was selected as the optimal formula presenting stable nanoemulsion for 2-month period, showing droplet size of 177.6 ± 13.23 nm, polydispersity index of 0.16 ± 0.06, zeta potential of -21.23 ± 0.41 mV. High SA% in different skin strata and no dermal irritation was noticed with limonene-based SA-NE also it showed high in-vitro anti- inflammatory potential compared to the blank and control formulations. A preclinical study demonstrated that limonene-based SA-NE is effective in alleviating psoriasis-like skin lesions against imiquimod-induced psoriasis in rats. Clinically, promising anti-psoriatic potential was asserted as all patients receiving F5 experienced better clinical improvement and response to therapy, achieving ≥ 50 % reduction in PASI scores versus only 35 % responders in the Dermovate® cream group. Collectively, the practical feasibility of limonene-based SA-NE topical delivery can boost curative functionality in the treatment of psoriatic lesions.

Factors, Mechanisms, and Kinetics of Spontaneous Emulsification for Heavy Oil-in-Water Emulsions

In challenging reservoirs where thermal recovery falls short, cold or chemical oil recovery methods are crucial. Spontaneous emulsification (SE), triggered by gentle disturbance, significantly enhances oil recovery. In elucidating SE mechanisms and kinetics, SE processes via direct contact between oil and aqueous phases without stirring were conducted. The effects of temperature, emulsifier concentration, pH, NaCl concentration, and the oil-to-water ratio on SE were investigated through droplet size analysis and turbidity measurements. Furthermore, the emulsification mechanism and derived emulsification kinetics based on turbidity data were obtained. The results underscore the feasibility of SE for oil-water systems, reducing viscous and capillary resistances without agitation. The emulsified oil mass increased with the temperature, pH, and aqueous-to-oil phase volume ratio while decreasing with the NaCl concentration. In this study, for GD-2 crude oil, the optimal emulsified oil amount occurred at a betaine surfactant (BetS-2) emulsifier concentration of 0.45%. Microscopic photo analysis indicated narrow particle size distributions and small droplets, which remained stable over time under various experimental conditions. A combined SE mechanism involving ultralow interfacial tension, interfacial turbulence due to Marangoni effects, and "diffusion and stranding" due to in situ emulsifier hydrophilicity, was speculated. Additionally, an analogous second-order kinetic equation for SE was proposed, indicating exceptional correlation with calculated and experimentally measured values. This study offers theoretical insight for enhancing oil recovery in chemical and cold production of heavy oil in oilfields.

Shrimp oil nanoemulsions prepared by microfluidization and ultrasonication: characteristics and stability

Shrimp oil (SO) nanoemulsions stabilized by fish myofibrillar protein, considered as functional foods, were prepared via microfluidization and ultrasonication. The study explored varying microfluidization (pressure and cycles) and ultrasonication (amplitude and sonication time) conditions that influenced emulsion properties and stability. Ultrasonicated emulsions exhibited superior emulsifying properties, adsorbed protein content, thermal stability, and centrifugal stability than microfluidized emulsions (p < 0.05). Microfluidization at 6.89 and 13.79 MPa with 2 or 4 cycles yielded larger droplets (536 to 638 nm) (p < 0.05), while ultrasonication at 40% and 50% amplitude for 5, 10 and 15 min produced smaller droplets (426 to 494 nm) (p < 0.05). Optimal conditions were obtained for microfluidization (13.79 MPa, 2 cycles) and ultrasonication (50% amplitude, 10 min). Ultrasonicated emulsions had generally smaller d32 and d43, lower polydispersity and higher ζ-potential than their microfluidized counterparts. Microstructural analysis and CLSM images confirmed their superior stability during storage. SO nanoemulsions could be applied as functional food.

Crocin-Phospholipid Complex: Molecular Docking, Molecular Dynamics Simulation, Preparation, Characterization, and Antioxidant Activity

Background

Crocin is a water-soluble carotenoid compound present in saffron (Crocus sativus L.), known for its wide range of pharmacological activities, including cardioprotective, hepatoprotective, anti-tumorigenic, anti-atherosclerosis, and anti-inflammatory effects.

Objectives

The instability of crocin, its low miscibility with oils, and poor bioavailability pose challenges for its pharmaceutical applications. This study aimed to design and prepare a crocin-phospholipid complex (CPC) and assess its physicochemical properties.

Methods

The study investigated the formation of the complex and its binding affinity through molecular docking. Molecular dynamics (MD) simulations were conducted to find the optimal molar ratio of crocin to phospholipid for the complex's preparation. The CPC was produced using the solvent evaporation method. Techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), nuclear magnetic resonance (NMR), and solubility studies were utilized to characterize and confirm the formation of CPC. Additionally, the in vitro antioxidant activity of crocin and CPC was evaluated.

Results

Molecular dynamic simulations explored molar ratios of 1: 1, 1: 1.5, and 1: 2 for crocin to phospholipid. The ratio of 1: 2 was found to be the most stable, exhibiting the highest probability of hydrogen bond formation. Molecular docking, FTIR, and NMR studies indicated hydrogen bond interactions between crocin and phospholipid, confirming CPC's formation. XRD and FE-SEM analyses showed a decrease in crocin's crystallinity within the phospholipid complex. Furthermore, the solubility of crocin in n-octanol was enhanced post-complexation, indicating an increase in crocin's lipophilic nature.

Conclusions

Phospholipid complexation emerges as a promising technique for enhancing the physicochemical characteristics of crocin.

Optimization of vitamin B12 nano-emulsification and encapsulation using spontaneous emulsification

In this study, the use of low-energy methods for nanoemulsification of vitamin B12 was investigated to protect this bioactive substance. The effects of sunflower oil concentrations (4-8%), Tween 80 (8-16%), and vitamin B12 (5-15%) on the physicochemical properties of B12 nanoemulsion were evaluated using response surface methodology (RSM). The results indicated that the quadratic model was the most fitting model for experimental data. Optimization revealed that the optimal formulation contained 6.5% sunflower oil, 9.6% Tween 80, and 13% vitamin B12, resulting in maximum efficiency, viscosity, and vitamin B12 content, as well as minimum pH, turbidity, p-Anisidine index, particle size, and polydispersity index (PDI). Under optimal conditions, pH, viscosity, turbidity, efficiency, vitamin B12, p-Anisidine index, PDI, and particle size were 7.24, 17.0024 cp, 2.19, 51.98%, 5.54 ppm, 0.01, 0.34, and 322 nm, respectively. This study highlights the effectiveness of spontaneous emulsification as a carrier for the encapsulation of bioactive compounds.

Peppermint essential oil and its nano-emulsion: Potential against aflatoxigenic fungus Aspergillus flavus in food and feed

A facultative parasite called Aspergillus flavus contaminates several important food crops before and after harvest. In addition, the pathogen that causes aspergillosis infections in humans and animals is opportunistic. Aflatoxin, a secondary metabolite produced by Aspergillus flavus, is also carcinogenic and mutagenic, endangering human and animal health and affecting global food security. Peppermint essential oils and plant-derived natural products have recently shown promise in combating A. flavus infestations and aflatoxin contamination. This review discusses the antifungal and anti-aflatoxigenic properties of peppermint essential oils. It then discusses how peppermint essential oils affect the growth of A. flavus and the biosynthesis of aflatoxins. Several cause physical, chemical, or biochemical changes to the cell wall, cell membrane, mitochondria, and associated metabolic enzymes and genes. Finally, the prospects for using peppermint essential oils and natural plant-derived chemicals to develop novel antifungal agents and protect foods are highlighted. In addition to reducing the risk of aspergillosis infection, this review highlights the significant potential of plant-derived natural products and peppermint essential oils to protect food and feed from aflatoxin contamination and A. flavus infestation.

Nano Uncaria gambir as Chemopreventive Agent Against Breast Cancer

BACKGROUND

Breast cancer is one of the main causes of death in women. Uncaria gambir is an Indonesian herbal plant that can be used as an anti-cancer. However, herbal medicines have low bioavailability, which affects their bioactivity. Nanoencapsulation can increase bioavailability and stability of bioactive compounds in herbal medicines.

PURPOSE

This recent finding tried to unravel anti-cancer and chemopreventive of U. gambir nano-encapsulated by Na-alginate.

STUDY DESIGN

U. gambir bioactive compounds were isolated and characterized using UV-Vis spectrometer, FTIR, NMR and HR-MS. U. gambir extract was nanoencapsulated using Na-alginate. Anti-cancer effect was assessed by MTT assay towards T47D cell. Meanwhile, a chemopreventive analysis was carried out in breast cancer mice-induced benzo[α]pyrene. The healthy mice were divided into 8 groups comprising control and treatment.

RESULTS

Elucidation of U. gambir ethyl acetate extract confirmed high catechin content, 89.34% (w/w). Successful nanoencapsulation of U. gambir (G-NPs) was indicated. The particle size of G-NPs was 78.40 ± 12.25 nm. Loading efficiency (LE) and loading amount (LA) of G-NPs were 97.56 ± 0.04% and 32.52 ± 0.01%, respectively. G-NPs had an EC50 value of 10.39 ± 3.50 µg/mL, which was more toxic than the EC50 value of extract towards the T47D cell line. Administration of 200 mg/kg BW G-NPs to mice induced by benzo[α]pyrene exhibited SOD and GSH levels of 13.69 ng/mL and 455.6 ng/mL. In addition, the lowest TNF-α level was 27.96 ng/mL. A dose of 100 mg/kg BW G-NPs could best increase CAT levels by 7.18 ng/mL. There was no damage or histological abnormalities found in histological analysis of the breast tissue in the group given 200 mg/kg BW G-NPs.

Recent insights into Nanoemulsions: Their preparation, properties and applications

The ever-increasing demand for healthy diet by consumers has prompted the research adopting cutting-edge methods that can maintain the quality of fruits and vegetables without the use of preservatives. Emulsion based coating approach has been regarded as a viable way to extend the shelf life of fresh produce. New opportunities are being created in a number of industries, (medicines, cosmetics and food) because of new advancements in the developing field of nanoemulsions. Nanoemulsion based methods are efficient for encapsulating the active ingredients including antioxidants, lipids, vitamins and antimicrobial agents owing to the small droplet size, stability and improved biological activity. This review provides an overview of recent developments in preserving the quality and safety of fresh-cut fruits & vegetables with nanoemulsion as a carrier of functional compounds (antimicrobial agents, antibrowning/antioxidants and texture enhancers). In addition, material and methods used for fabrication of the nanoemulsion is also described in this review. In addition, material and methods used for fabrication, of the nanoemulsion is also present.

Optimization of water/oil emulsion preparation: Impact of time, speed, and homogenizer type on droplet size and dehydration efficiency

Due to their distinctive physical and chemical properties, emulsions are widely used in various industries such as pharmaceuticals, cosmetics, food, energy, and oil. Emulsion preparation differs from one application to another due to the effect of multiple parameters that can control droplet size and stability. However, there is a lack of fundamental understanding of the effect of emulsion preparation on its stability and performance. The emulsion preparation protocols can directly affect dehydration efficiency and stability. Herein, we report the influence of preparation conditions on the properties of the formed emulsions; we investigated the effect of mixing time, speed, and mixer type on the synthetic crude oil emulsion's droplet size and dehydration efficiency.

On the Importance of the Starting Material Choice and Analytical Procedures Adopted When Developing a Strategy for the Nanoencapsulation of Saffron (Crocus sativus L.) Bioactive Antioxidants

Saffron is known as the most expensive spice in the world. It is comprised of the dried stigmas of the pistil of the Crocus sativus L., which is a cultivated, sterile crocus plant. This plant material is now recognized as the unique edible source of certain bioactive apocarotenoids for which in-vivo antioxidant properties have been reported. Among the latter, crocins, red-orange natural colorants, and their parent molecule crocetin prevail in bioactivity significance. This review is focused on the strategies developed so far for their nanoencapsulation in relation to the characteristics of the starting material, extraction procedures of the bioactive antioxidants and analytical methods applied for their characterization and quantification throughout the process. The literature so far points out gaps that lead to publishable data, on one hand, but not necessarily to repeatable and meaningful processes due to incomplete characterization of the starting and the released material in efficiency and stability studies of the nanoencapsulates. Accurate terminology and quantitative chromatographic or spectrophotometric procedures for the determination of the core compounds are needed. Authenticity control and quality of saffron samples, and the verification of the concentrations of compounds in commercial preparations labeled as 'crocin,' are prerequisites in any experimental design setup.

Anti-oxidative properties of nanocrocin in Zearalenone induced toxicity on Hek293 cell; The novel formulation and cellular assessment

BACKGROUND

Zearalenone (ZEA) is a mycotoxin produced by fungi and induces cytotoxicity by the generation of reactive oxygen species. The aim of this study was to evaluate and compare the nephroprotective effects of crocin and nano-crocin against ZEA-induced toxicity in HEK293 cell line via modulation of oxidative stress and special formulation to make nano-crocin.

METHOD

Nano-crocin physicochemical properties, such as size, load, appearance, and drug release profile were determined. Also, the viability of intoxicated HEK293 cells was evaluated by MTT assay. Furthermore, lactate dehydrogenase lipid Peroxidation (LPO), and oxidative stress biomarkers were measured.

RESULT

The best nano-crocin formulation with superior entrapment effectiveness (54.66 ± 6.02), more significant drug loading (1.89 ± 0.01), better zeta potential (-23.4 ± 2.844), and smaller particle size (140.3 ± 18.0 nm) was chosen. This study showed that treatment with crocin and nano-crocin in ZEA-induced cells, significantly decreased LDH and LPO levels and increased superoxide dismutase (SOD), catalase (CAT) activities, and total antioxidant capacity (TAC) levels compared to the control group. Moreover, nano-crocin had a more curative effect against oxidative stress than crocin.

CONCLUSION

Niosomal structure of crocin, when administered with the special formulation, may be more beneficial in reducing ZEA-induced in vitro toxicity than conventional crocin.

Crocin: Functional characteristics, extraction, food applications and efficacy against brain related disorders

Crocin is a bioactive compound that naturally occurs in some medicinal plants, especially saffron and gardenia fruit. Different conventional and novel methods are used for its extraction. Due to some control conditions, recent methods such as ultrasonic extraction, supercritical fluid extraction, enzyme-associated extraction, microwave extraction, and pulsed electric field extraction are widely used because these methods give more yield and efficiency. Crocin is incorporated into different food products to make functional foods. However, it can also aid in the stability of food products. Due to its ability to protect against brain diseases, the demand for crocin has been rising in the pharmaceutical industry. It also contain antioxidant, anti-inflammatory, anticancer and antidepressant qualities. This review aims to describe crocin and its role in developing functional food, extraction, and bioavailability in various brain-related diseases. The results of the literature strongly support the importance of crocin against various diseases and its use in making different functional foods.

Boosting Tadalafil Bioavailability via Sono-Assisted Nano-Emulsion-Based Oral Jellies: Box-Behnken Optimization and Assessment

Tadalafil (TAD) is a poorly soluble, phosphodiesterase inhibitor used to treat erectile dysfunction. The primary goal of this project was to prepare nano-emulsions using ultrasonic technology to address TAD bioavailability concerns. The Box−Behnken design was employed to find prominent correlations between factors impacting the sono-emulsification process. The emulsifier concentration, amplitude level, and ultrasonication time were the independent factors, whereas the average droplet size (ADS) and polydispersity index (PDI) were designated as the response variables. TAD-loaded nano-emulsions (93−289 nm) were generated and the emulsifier concentration showed a crucial role in directing emulsion droplet size. The model desirability function was utilized to optimize a nano-emulsion with a small ADS (99.67 ± 7.55 nm) and PDI (0.45 ± 0.04) by adjusting the emulsifiers concentration, amplitude level, and ultrasonication time at 9.85%, 33%, 49 s, respectively. The optimized nano-emulsions did not demonstrate any precipitation or phase separation after stability stress tests. TAD jellies were formulated based on the optimized nano-emulsion and subjected to in vitro evaluation for physical characteristics; TAD content, pH, spreadability, viscosity, syneresis, and taste-masking ability. An optimized nano-emulsion-based jelly (NEJ) formulation showed more than 96% drug dissolution in 30 min relative to 14% for the unprocessed TAD. In vivo assessment of NEJ in experimental rats demonstrated a significant enhancement (p < 0.05) of TAD bioavailability with an AUC0−24h of 2045 ± 70.2 vs. 259.9 ± 17.7 ng·h·mL−1 for the unprocessed TAD. Storage stability results revealed that NEJ remained stable with unremarkable changes in properties for 3 months. Overall, NEJ can be regarded as a successful therapeutic option for TAD administration with immediate-release properties and improved bioavailability.

Optimisation of Calophyllum inophyllum seed oil nanoemulsion as a potential wound healing agent

Background

Efficient delivery systems of Calophyllum inophyllum seed oil (CSO) in the form of nanoemulsion were optimised to enhance its stability and ensure its therapeutic efficiency as a potential agent for various biomedical applications.

Method

Response Surface Methodology (RSM) was used to determine the effects of independent variables (oil, surfactant, water percentage and homogenisation time) on physicochemical characteristics, including droplet size, polydispersity index and turbidity.

Results

The optimised CSO nanoemulsion (CSONE) has a 46.68 nm particle size, 0.15 Polydispersity index value and 1.16 turbidity. After 4 weeks of storage at 5 ± 1 °C and 25 ± 1 °C, the CSONE was physically stable. The optimised CSO nanoemulsion showed enhancement in cell viability and wound healing in baby hamster kidney a clone BHK-21 (BSR) cells as compared to the CSO. The wound healing property of CSONE was higher than CSO.

Conclusion

Thus, our in vitro wound healing results demonstrated that CSO in the nanoemulsion form can promote wound healing by enhancing the proliferation and migration of epidermal cells.

Graphical Abstract

The coarse emulsion of Calophyllum inophyllum seed oil nano emulsion was prepared using high shear homogeniser techniques. The optimised CSONE with the droplet size of 46.68 nm was prepared from a mixture of CSO, Tween 80, and high pure water (HPW), then used for the biological investigation. The in vitro cell monolayer scratch assay revealed that CSONE in the lowest concentration of CSO resulted in 100% wound closure after 48 hrs. The optimised CSO nanoemulsion was found to be a promising and effective approach in the treatment of wounds by boosting the proliferation and migration of epidermal cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03751-6.

Spontaneous Emulsions: Adjusting Spontaneity and Phase Behavior by Hydrophilic-Lipophilic Difference-Guided Surfactant, Salt, and Oil Selection

Spontaneous emulsion behavior has been difficult to predict and could be influenced by many variables including salinity, temperature, and chemical composition of the oil and surfactant. In this work, the hydrophilic-lipophilic difference (HLD) framework was used to predict the formation of spontaneous emulsions using a mixture of Span-80 and SLES surfactants. The spontaneity and emulsion behavior of different systems were modeled by estimating the HLD_mix. The influence of surfactant ratio, salinity, and oil type was investigated. Spontaneous emulsification could only be observed when the HLD_mix was between -0.96 and 1.04. Within this range, a negative HLD_mix resulted in a greater spontaneity to form o/w emulsion, and a w/o emulsion was more likely to form when the HLD_mix was positive. When the HLD_mix was close to 0 (between -0.22 and 0.56 in our systems), emulsions were formed in both the oil and aqueous phases with high spontaneity. A combined effect of ultralow interfacial tension, Span-80 micelle swelling, and interfacial turbulence due to Marangoni effects is likely the main mechanism of the spontaneous emulsification observed in this study. A synergistic reduction in interfacial tension was observed between Span-80 and SLES (<1 mN/m). When the HLD of the system was close to 0, a bicontinuous emulsion phase was formed at the oil-water interface. The bicontinuous emulsion broke-up over time due to the ultralow interfacial tension and interfacial turbulence, forming dispersed oil and water droplets. Results from this work provide a practical method to suggest what surfactant composition, salinity, and oil type could promote (or eliminate) the conditions favorable for spontaneous emulsification.

D-optimal mixture design for optimization of topical dapsone niosomes: in vitro characterization and in vivo activity against Cutibacterium acnes

This study aimed to illustrate the use of D-optimal mixture design (DOMD) for optimization of an enhancer containing Dapsone niosomal formula for acne topical treatment. Mixture components (MixCs) studied were: Span 20, Cholesterol, and Cremophor RH. Different responses were measured. Optimized formula (OF) was selected to minimize particle size and maximize absolute zeta potential and entrapment efficiency. Optimized formula gel (OF-gel) was prepared and characterized. OF-gel in vivo skin penetration using confocal laser scanning microscopy and activity against Cutibacterium acnes in acne mouse model were studied. Based on DOMD results analysis, adequate models were derived. Piepel and contour plots were plotted accordingly to explain how alteration in MixCs L-pseudo values affected studied responses and regions for different responses’ values. The OF had suitable predicted responses which were in good correlation with the actually measured ones. The OF-gel showed suitable characterization and in vivo skin penetration up to the dermis layer. In vivo acne mouse-model showed that OF-gel-treated group (OF-gel-T-gp) had significantly better recovery (healing) criteria than untreated (UT-gp) and Aknemycin^®-treated (A-T-gp) groups. This was evident in significantly higher reduction of inflammation percent observed in OF-gel-T-gp than both UT-gp and A-T-gp. Better healing in OF-gel-T-gp compared with other groups was also verified by histopathological examination. Moreover, OF-gel-T-gp and A-T-gp bacterial loads were non-significantly different from each other but significantly lower than UT-gp. Thus, DOMD was an adequate statistical tool for optimization of an appropriate enhancer containing Dapsone niosomal formula that proved to be promising for topical treatment of acne.

Use of nanosystems to improve the anticancer effects of curcumin

Curcumin (CUR) is a phenolic compound that is safe for human consumption. It exhibits chemopreventive, antiproliferative, antiangiogenic, and antimetastatic effects. However, these benefits can be hampered due to the lipophilic nature, rapid metabolism, low bioavailability, and fast elimination of the molecule. Considering this, the present work reviews the use of CUR-based nanosystems as anticancer agents, including conventional nanosystems (i.e., liposomes, nanoemulsions, nanocrystals, nanosuspensions, polymeric nanoparticles) and nanosystems that respond to external stimuli (i.e., magnetic nanoparticles and photodynamic therapy). Previous studies showed that the effects of CUR were improved when loaded into nanosystems as compared to the free compound, as well as synergist effects when it is co-administrated alongside with other molecules. In order to maximize the beneficial health effects of CUR, critical factors need to be strictly controlled, such as particle size, morphology, and interaction between the encapsulating material and CUR. In addition, there is an area of study to be explored in the development of CUR-based smart materials for nanomedical applications. Imaging-guided drug delivery of CUR-based nanosystems may also directly target specific cells, thereby increasing the therapeutic and chemopreventive efficacy of this versatile compound.

Micro and Nanoencapsulation of Natural Colors: a Holistic View

The applications of natural plant pigments are growing rapidly with the increasing awareness of the negative health impacts of synthetic colorants. Additionally, natural pigments possess various biological properties and therapeutic activities. But their functions are hindered by their poor bioavailability, bioaccessibility, low absorption rate, and susceptibility to destructive environmental changes during processing and delivery. Encapsulation is a method of entrapment of bioactive ingredients within suitable carriers to provide protection and for the appropriate delivery into the targeted site by the formation of particles or capsules in micrometer or nanometer scales. Encapsulation imparts several benefits including improved thermal and chemical stability, preserves or masks flavor, taste, or aroma, controlled and targeted release, and enhanced bioavailability of pigments. Micro and nanoencapsulation of pigments will provide extensive and intensive platforms for the development of a new stage in the production of novel and healthy foods. This review mainly focuses on the advanced developments in the fields of micro and nanoencapsulation of pigments.

Water-in-Oil Nano-Emulsions Prepared by Spontaneous Emulsification: New Insights on the Formulation Process

Nano-emulsions consist of stable suspensions of nano-scaled droplets that have huge loading capacities and are formulated with safe compounds. For these reasons, a large number of studies have described the potential uses of nano-emulsions, focusing on various aspects such as formulation processes, loading capabilities, and surface modifications. These studies typically concern direct nano-emulsions (i.e., oil-in-water), whereas studies on reverse nano-emulsions (i.e., water-in-oil) remain anecdotal. However, reverse nano-emulsion technology is very promising (e.g., as an alternative to liposome technology) for the development of drug delivery systems that encapsulate hydrophilic compounds within double droplets. The spontaneous emulsification process has the added advantages of optimization of the energetic yield, potential for industrial scale-up, improved loading capabilities, and preservation of fragile compounds targeted for encapsulation. In this study, we propose a detailed investigation of the processes and formulation parameters involved in the spontaneous nano-emulsification that produces water-in-oil nano-emulsions. The following details were addressed: (i) the order of mixing of the different compounds (method A and method B), (ii) mixing rates, (iii) amount of surfactants, (iv) type and mixture of surfactants, (v) amount of dispersed phase, and (vi) influence of the nature of the oil. The results emphasized the effects of the formulation parameters (e.g., the volume fraction of the dispersed phase, nature or concentration of surfactant, or nature of the oil) on the nature and properties of the nano-emulsions formed.

Comparison of binary cress seed mucilage (CSM)/β-lactoglobulin (BLG) and ternary CSG-BLG-Ca (calcium) complexes as emulsifiers: Interfacial behavior and freeze-thawing stability

Protein-polysaccharide complexes often exhibit amended techno-functional characteristics when compared to their individual participant biomolecules. In this study, a complex coacervation of cress seed mucilage (CSM)/β-lactoglobulin (Blg) was used for stabilizing oil-in-water emulsions; they were characterized in terms of physical properties, droplet-size distribution and microstructure. Also, a comprehensive study was carried out on interfacial rheological responses and on the corresponding emulsion stability of different complexes. Freeze-thaw stability of the produced emulsions which had from mixtures of CSM-Blg was also evaluated. More than the size of droplets, interfacial rheological characteristics were associated with the properties of the adsorbed layers and with the stability of emulsions in storage. Using the CSM-Blg-Ca ultimately resulted in emulsions that proved stable against creaming, with no sign of phase separation over 3 weeks. These results show protein-polysaccharide complexes as appropriate emulsifiers that can make emulsion-based products resistant to unwanted changes caused by freeze-thawing.

Effect of environmental stresses on physicochemical properties of ALA oil-in-water nanoemulsion system prepared by emulsion phase inversion

To solve the stability and oxidation issues of alpha-linolenic acid (ALA), this study focused on developing ALA nanoemulsion system (ALA-NE, oil-in-water) and evaluating the effect of environmental conditions on physical stability and the effect of antioxidants on oxidative stability. The physicochemical properties of nanoemulsions were measured at different conditions, including particle diameter, zeta potential, retention rate and peroxidation value (POV). The particle diameter increased significantly and the retention rate decreased after 25 days storage under the conditions of high temperature and metal ions. However, the influence of ionic strength, pH and light was insignificant. As an antioxidant, Vitamin E was more effective at retarding lipid oxidation of nanoemulsions than that of vitamin C. These results provided reference information in preparing effective and stable ALA-NE systems and enlarging the application fields.

Microemulsions as nano-reactors for the solubilization, separation, purification and encapsulation of bioactive compounds

Bioactive components possess various functionalities and are most interested for different food, nutraceutical and pharmaceutical formulations. The current review will discuss the preparation methods and fabrication techniques to design microemulsions (MEs) for the solubilization, separation, encapsulation and purification of various agro-food bioactive compounds. ME systems have shown suitable potential in enhancing oil recovery, protein extraction, and isolation of bioactive compounds. Moreover, the capability of ME based systems as drug and nutraceutical delivery cargos, and synthesis of various organic and inorganic nanoparticles, especially using biopolymers, will be investigated. ME liquid membranes are also developed as nano-extractor/nano-reactor vehicles, capable of simultaneous extraction, encapsulation or even synthesis of hydrophilic and lipophilic bioactive compounds for food, nutraceutical and drug applications.

Efficacies of Two Nano-Formulations of Tasmanian Blue Gum Essential Oil to Control Callosobruchus maculatus

Botanical insecticides, including essential oils (EOs), can be considered as appropriate alternatives to synthetic insecticides for controlling stored product pests. In this study, potential of nano-formulations of the Tasmanian blue gum (TBG) EO to control Callosobruchus maculatus Fabricius (Coleoptera, Bruchidae) were evaluated under laboratory condition. Two nano-emulsion formulations of the EO were provided using gum Arabic and Span 80 as surfactants. Contact as well as fumigant toxicities of the formulations to the beetle adults were compared with the bulk EO in 1, 2, and 3 d after treatment. Results showed that all formulations were toxic to the adults. After 1, 2, and 3 d of treatment, the estimated LC50 values in contact and fumigant applications varied from 1.37 to 8.53 ppm and 0.05 to 0.44 ppm for various formulations. Both nano-formulations cause significant stability enhancement of the EO. Moreover, the EO had significant repellent and ovicidal effects on the insect. The insecticidal effects of the EO in nano-formulations were significantly greater than in the bulk form. The EO constituted 22 compounds, from 5 classes. Eucalyptol (43.79%) is the main constituent of the TBG EO.

Formulation and Application of Nanoemulsions for Nutraceuticals and Phytochemicals

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Recent trends in research and investigation on nanoemulsion based products is the result of many reasons such as food security as a global concern, increasing demand for highly efficient food and agricultural products and technological need for products with the ability of manipulation and optimization in their properties. Nanoemulsions are defined as emulsions made up of nano sized droplets dispersed in another immiscible liquid which exhibit properties distinguishing them from conventional emulsions and making them suitable for encapsulation, delivery and formulations of bioactive ingredients in different fields including drugs, food and agriculture. The objective of this paper is to present a general overview of nanoemulsions definition, their preparation methods, properties and applications in food and agricultural sectors. Due to physicochemical properties of the nanoemulsion composition, creating nanosized droplets requires high/low energy methods that can be supplied by special devices or techniques. An overview about the mechanisms of these methods is also presented in this paper which are commonly used to prepare nanoemulsions. Finally, some recent works about the application of nanoemulsions in food and agricultural sectors along with challenges and legislations restricting their applications is discussed in the last sections of the current study.

Effects of Ultrasonic Operating Parameters and Emulsifier System on Sacha Inchi Oil Nanoemulsion Characteristics

The objective of this study was to investigate the effect of ultrasonic operating conditions, i.e., ultrasonic mode, amplitude, total ultrasonic duration time, and emulsifier system in producing an optimum oil-in-water of sacha inchi oil nanoemulsions (SIO-NEs). Physicochemical characteristics (including average droplet size, polydispersity index (PDI), zeta potential, and viscosity) were the evaluated response variables. Smaller droplet size was obtained from SIO-NEs prepared by ultrasonic pulse application (15s ON and 10s OFF) with an ultrasonic amplitude level of 60%. In contrast, excess energy produced by ultrasonication amplitudes of more than 60% resulted in larger average droplet size and PDI. A decrease in the absolute value of zeta potential and a lower viscosity of SIO-NEs were also observed in conjunction with the high amplitude level of the ultrasonication process. An ultrasonication duration time of longer than 10 minutes did not significantly reduce the droplet size. Five emulsifier systems were evaluated in this study, including Pluronic^®L-31, Brij^®C-10, Tween^®80, Tween^®80/Pluronic^®L-31, and Brij^®C-10/Pluronic^®L-31. The results revealed that the Brij^®C-10/Pluronic^®L-31 mixture produced the smallest droplet size (148 nm) with the lowest PDI (0.210), viscosity (3.35 cPs), and zeta potential (－31.09 mV). The concentration of the Brij^®C-10/Pluronic^®L-31 mixture, used as an emulsifier of SIO-NEs, varied from 1.5% to 9%. Based on the present findings, the most suitable concentration of mixed emulsifier used was deemed as 3% (w/v). The selected SIO-NEs were stored under room temperature to determine their droplet size stability, with the constant slightly increasing within 90 days of storage.

Advances of spontaneous emulsification and its important applications in enhanced oil recovery process

Emulsions, including oil-in-water (O/W) and water-in-oil (W/O) emulsions, can play important roles in both controlling reservoir conformance and displacing residual oil for enhanced oil recovery (EOR) projects. However, current methods, like high-shear mixing, high-pressure homogenizing, sonicators and others, often use lots of extra energy to prepare the emulsions with high costs but very low energy efficiency. In recent decades, spontaneous emulsification methods, which allow one to create micro- and nano-droplets with very low or even no mechanical energy input, have been launched as an overall less expensive and more efficient alternatives to current high extra energy methods. Herein, we primarily review the basic concepts on spontaneous emulsification, including mechanisms, methods and influenced parameters, which are relevant for fundamental applications for industrials. The spontaneity of the emulsification process is influenced by the following variables: surfactant structure, concentration and initial location, oil phase composition, addition of co-surfactant and non-aqueous solvent, as well as salinity and temperature. Then, we focus on the description of importance for emulsions in EOR processes from advances and categories to improving oil recovery mechanisms, including both sweep efficiency and displacement efficiency aspects. Finally, we systematically address the applications and outlooks based on the use of spontaneous emulsification in the practical oil reservoirs for EOR processes, in which conventional, heavy, high-temperature, high-salinity and low-permeability oil reservoirs, as well as wastewater treatments after EOR processes are involved.

Comparison of Engine Performance between Nano- and Microemulsions of Solketal Droplets Dispersed in Diesel Assisted by Microwave Irradiation

As a derivative product of bio-glycerol, this study first uses solketal as a combustion improver for enhancing diesel engine characteristics. The emulsions of nanometer- and micrometer-sized droplets of solketal, which disperse evenly in the ultra-low sulfur diesel (ULSD), are formed by the effects of microwave irradiation. The performance of diesel engine fueled with the nanoemulsion of ULSD with scattered solketal droplets is analyzed and compared to that with the microemulsion. The experimental results show that the nanoemulsions can form when over 15 wt. % surfactant mixtures of Span 80 and Tween 80 and less than 5 wt. % solketal are mixed and emulsified with the remaining ULSD content, which acts as the continuous phase of the emulsions. The nanoemulsions are observed to have significantly lower brake-specific fuel consumption (bsfc) and higher fuel conversion efficiency and exhaust gas temperature than those of the microemulsions and the neat ULSD. However, the bsfc of the nanoemulsions increases with greater engine speed and gradually approaches those of the latter two test fuels. In addition, the dispersed solketal droplet sizes are mostly concentrated around 127 nm with peak intensity of 12.65% in the nanoemulsions. The microwave-assisted formation used in this study is found to successfully produce the nanoemulsions in which all of the dispersed droplet sizes are much smaller than 1000 nm.

Nanoemulsions: Factory for Food, Pharmaceutical and Cosmetics

Nanotechnology, particularly nanoemulsions (NEs), have gained increasing interest from researchers throughout the years. The small-sized droplet with a high surface area makes NEs important in many industries. In this review article, the components, properties, formation, and applications are summarized. The advantages and disadvantages are also described in this article. The formation of the nanosized emulsion can be divided into two types: high and low energy methods. In high energy methods, high-pressure homogenization, microfluidization, and ultrasonic emulsification are described thoroughly. Spontaneous emulsification, phase inversion temperature (PIT), phase inversion composition (PIC), and the less known D-phase emulsification (DPE) methods are emphasized in low energy methods. The applications of NEs are described in three main areas which are food, cosmetics, and drug delivery.

Gum-based nanocarriers for the protection and delivery of food bioactive compounds

Gums, which for the most part are water-soluble polysaccharides, can interact with water to form viscous solutions, emulsions or gels. Their desirable properties, such as flexibility, biocompatibility, biodegradability, availability of reactive sites for molecular interactions and ease of use have led to their extremely large and broad applications in formation of nanostructures (nanoemulsions, nanoparticles, nanocomplexes, and nanofibers) and have already served as important wall materials for a variety of nano encapsulated food ingredients including flavoring agents, vitamins, minerals and essential fatty acids. The most common gums used in nano encapsulation systems include Arabic gum, carrageenan, xanthan, tragacanth plus some new sources of non-traditional gums, such as cress seed gum and Persian/or Angum gum identified as potential building blocks for nanostructured systems. New preparation techniques and sources of non-traditional gums are still being examined for commercialization in the food nanotechnology area as low-cost and reproducible sources. In this study, different nanostructures of gums and their preparation methods have been discussed along with a review of gum nanostructure applications for various food bioactive ingredients.

Ultrasound-assisted water-in-palm oil nano-emulsion: Influence of polyglycerol polyricinoleate and NaCl on its stability

This study aimed to formulate a stable palm oil-based water-in-oil (W/O) nano-emulsion. Emphasis was placed on the effects of polyglycerol polyricinoleate (PGPR), medium chain triglyceride (MCT), lecithin and sodium chloride (NaCl) addition towards the stability of nano-emulsion. Among the performed analyses were mean droplet diameter (MDD), dispersity index (DI), critical micelle concentration (CMC), lipid peroxidation, viscosity, sedimentation index (SI) and surface morphology. The most stable optimized palm oil-based W/O nano-emulsion was produced using 61.25 wt% of palm oil, 26.25 wt% of MCT, 2.5 wt% of PGPR and 10 wt% of water (0.5 M of NaCl). The MDD and DI of the obtained W/O nano-emulsion were 143.1 ± 8.8 and 0.131 ± 0.094, respectively. After 2 weeks, no sedimentation was observed in W/O nano-emulsion with MDD and DI were 151.2 ± 6.5 nm and 0.156 ± 0.025 respectively. This study clearly found that polyricinoleate non-polar fatty acids of PGPR bound to non-polar fatty acids of palm oil through van der Waals intermolecular forces. While, polyglycerol polar head of PGPR interacts with water molecules through hydrogen bonding, as well as by the bound glyceride units of palm oil. The addition of NaCl further reduced MDD by 70 nm and improved the stability of nano-emulsion through electrostatic and steric repulsions attributed to the dissociation of Na⁺ and Cl^- ions. This study aids to widen the knowledge and interest on the utilization of palm oil for the generation of W/O nano-emulsion, as well as to better understand the interaction between palm oil and PGPR/NaCl in producing nano-emulsion.

A systematic review on nanoencapsulation of food bioactive ingredients and nutraceuticals by various nanocarriers

Today, there is an ever-growing interest on natural food ingredients both by consumers and producers in the food industry. In fact, people are looking for those products in the market which are free from artificial and synthetic additives and can promote their health. These food bioactive ingredients should be formulated in such a way that protects them against harsh process and environmental conditions and safely could be delivered to the target organs and cells. Nanoencapsulation is a perfect strategy for this situation and there have been many studies in recent years for nanoencapsulation of food components and nutraceuticals by different technologies. In this review paper, our main goal is firstly to have an overview of nanoencapsulation techniques applicable to food ingredients in a systematic classification, i.e., lipid-based nanocarriers, nature-inspired nanocarriers, special-equipment-based nanocarriers, biopolymer nanocarriers, and other miscellaneous nanocarriers. Then, application of these cutting-edge nanocarriers for different nutraceuticals including phenolic compounds and antioxidants, natural food colorants, antimicrobial agents and essential oils, vitamins, minerals, flavors, fish oils and essential fatty acids will be discussed along with presenting some examples in each field.