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

Kelvin-Helmholtz instability as one of the key features for fast and efficient emulsification by hydrodynamic cavitation

The paper investigates the oil-water emulsification process inside a micro-venturi channel. More specifically, the possible influence of Kelvin-Helmholtz instability on the emulsification process. High-speed visualizations were conducted inside a square venturi constriction with throat dimensions of 450 µm by 450 µm, both under visible light and X-Rays. We show that cavity shedding caused by the instability results in the formation of several cavity vortices. Their rotation causes the deformation of the oil stream into a distinct wave-like shape, combined with fragmentation into larger drops due to cavitation bubble collapse. Later on, the cavity collapse further disperses the larger drops into a finer emulsion. Thus, it turns out that the Kelvin-Helmholtz instability is similarly characteristic for hydrodynamic cavitation emulsification inside a microchannel as is the Rayleigh-Taylor instability for acoustically driven emulsion formation.

Biomacromolecular carriers based hydrophobic natural products for potential cancer therapy

Cancer is the second leading cause of death worldwide. It was estimated that 90 % of cancer-related deaths were attributable to the development of multi-drug resistance (MDR) during chemotherapy, which results in ineffective chemotherapy. Hydrophobic natural products plays a pivotal role in the field of cancer therapy, with the potential to reverse MDR in tumor cells, thereby enhancing the efficacy of tumor therapy. However, their targeted delivery is considered a major hurdle in their application. The advent of numerous approaches for encapsulating bioactive ingredients in the nanodelivery systems has improved the stability and targeted delivery of these biomolecules. The manuscript comprehensively analyses the nanodelivery systems of bioactive compounds with potential cancer therapy applications, including liposomes, emulsions, solid lipid nanoparticles (NPs), and polymeric NPs. Then, the advantages and disadvantages of various nanoagents in the treatment of various cancer types are critically discussed. Further, the application of multiple-compbine delivery methods to overcome the limitations of single-delivery have need critically analyzed, which thus could help in the designing nanodrug delivery systems for bioactive compounds in clinical settings. Therefore, the review is timely and important for development of efficient nanodelivery systems involving hydrophobic natural products to improve pharmacokinetic properties for effective cancer treatment.

Innovative multiple nanoemulsion (W/O/W) based on Chilean honeybee pollen improves their permeability, antioxidant and antibacterial activity

Beehive derivatives, including honeybee pollen (HBP), have been extensively studied for their beneficial health properties and potential therapeutic use. Its high polyphenol content gives it excellent antioxidant and antibacterial properties. Today its use is limited due to poor organoleptic properties, low solubility, stability, and permeability under physiological conditions. A novel edible multiple W/O/W nanoemulsion (BP-MNE) to encapsulate the HBP extract was designed and optimized to overcome these limitations. The new BP-MNE has a small size (∼100 nm), a zeta potential greater than +30 mV, and efficiently encapsulated phenolic compounds (∼82%). BP-MNE stability was measured under simulated physiological conditions and storage conditions (4 months); in both cases, stability was promoted. The formulation's antioxidant and antibacterial (Streptococcus pyogenes) activity was analyzed, obtaining a higher effect than the non-encapsulated compounds in both cases. In vitro permeability was tested, observing a high permeability of the phenolic compounds when they are nanoencapsulated. With these results, we propose our BP-MNE as an innovative solution to encapsulate complex matrices, such as HBP extract, as a platform to develop functional foods.

Development of Niacinamide/Ferulic Acid-Loaded Multiple Emulsion and Its In Vitro/In Vivo Investigation as a Cosmeceutical Product

Objective

Multiple emulsions have the ability to incorporate both lipophilic and hydrophilic actives in the same preparation and facilitate permeation of active ingredients through skin. The current study was aimed at formulating niacinamide/ferulic acid-loaded stable multiple emulsion (MNF) and its in vitro/in vivo characterization as a cosmeceutical product.

Methods

Both the compounds were evaluated for their radical scavenging potential by the DPPH method and FTIR analysis. Then, placebo and active formulations were prepared using a double emulsification method and were investigated for stability testing (changes in color, odor, and liquefaction on centrifugation, pH, and globule size) for a period of three months. Afterwards, MNF was investigated for in vitro sun protection factor, rheological studies, entrapment efficiency, zeta potential, zeta size, and ex vivo permeation. Moreover, after ensuring the hypoallergenicity and safety, it was also checked for its cosmeceutical effects on human skin using noninvasive biophysical probes in comparison with placebo.

Results

Results demonstrated that MNF showed a non-Newtonian behavior rheologically and both MNF and placebo were stable at different storage conditions. Entrapment efficiency, zeta potential, and zeta size were 93.3%, -5.88 mV, and 0.173 μm, respectively. Moreover, melanin, sebum, and skin erythema were significantly reduced while skin elasticity and hydration were improved.

Conclusion

It is evident that niacinamide and ferulic acid can be successfully incorporated in a stable multiple emulsion which has potent cosmeceutical effects on human skin.

Encapsulation of volatile compounds in liquid media: Fragrances, flavors, and essential oils in commercial formulations

The first marketed example of the application of microcapsules dates back to 1957. Since then, microencapsulation techniques and knowledge have progressed in a plethora of technological fields, and efforts have been directed toward the design of progressively more efficient carriers. The protection of payloads from the exposure to unfavorable environments indeed grants enhanced efficacy, safety, and stability of encapsulated species while allowing for a fine tuning of their release profile and longer lasting beneficial effects. Perfumes or, more generally, active-loaded microcapsules are nowadays present in a very large number of consumer products. Commercial products currently make use of rigid, stable polymer-based microcapsules with excellent release properties. However, this type of microcapsules does not meet certain sustainability requirements such as biocompatibility and biodegradability: the leaking via wastewater contributes to the alarming phenomenon of microplastic pollution with about 4% of total microplastic in the environment. Therefore, there is a need to address new issues which have been emerging in relation to the poor environmental profile of such materials. The progresses in some of the main application fields of microencapsulation, such as household care, toiletries, cosmetics, food, and pesticides are reviewed herein. The main technologies employed in microcapsules production and the mechanisms underlying the release of actives are also discussed. Both the advantages and disadvantages of every technique have been considered to allow a careful choice of the most suitable technique for a specific target application and prepare the ground for novel ideas and approaches for encapsulation strategies that we expect to be proposed within the next years.

Strategies of confining green tea catechin compounds in nano-biopolymeric matrices: A review

Catechins are polyphenolic compounds which abundantly occur in the plants, especially tea leaves. They are widely used in nutraceutical and pharmaceutical formulations due to their capability of lowering the risk of developing various diseases. Nevertheless, low stability, loss of antioxidant and antimicrobial activities hinder the direct application of catechins in food formulations. To surmount this pervasive challenge, bioactive ingredients should be entrapped in a biopolymeric matrix. Thus, nanoencapsulation technology would be an appropriate strategy to improve the stability of these bioactive compounds and to protect them against degradation. Among different types of nanocarriers, biopolymer-based nanovehicles has captured a lot of attention in both industry and academia due to their safety and biocompatibility. This revision enlarges upon the various types of biopolymeric nanostructures used for accommodation of catechins, namely nanogels, nanotubes, nanofibers, nanoemulsions and nanoparticles. Last but not least, the applications of the entrapped catechins in the food industry are highlighted.

Water-in-Oil-in-Water Nanoemulsions Containing Temulawak (Curcuma xanthorriza Roxb) and Red Dragon Fruit (Hylocereus polyrhizus) Extracts

Hydrophobic curcumin in temulawak extract and hydrophilic betacyanin in red dragon fruit extract are high-value bioactive compounds with extensive applications in functional food. In this study, these extracts were encapsulated in water-in-oil-in-water (w/o/w) nanoemulsions as a delivery system using a two-step high-energy emulsification method. PGPR and Span 20 were used as lipophilic emulsifiers for the primary w/o emulsion. The most stable w/o/w formulation with the least oil phase separation of 5% v/v consisted of w/o emulsion (15% w/w) and Tween 80 (1.5% w/w) as hydrophilic emulsifier. The formulation was characterized by a 189-nm mean droplet diameter, 0.16 polydispersity index, and –32 mV zeta potential. The freeze–thaw stability may be attributed to the combination of low w/o emulsion content and high Tween 80 concentration in the outer water phase of the w/o/w nanoemulsions used in this study. The IC₅₀ values of the nanoemulsion and the red dragon fruit extract were similar. It means that the higher concentration of curcumin in the nanoemulsions and the lower IC₅₀ value of temulawak extract ensured sufficient antioxidant activities of the w/o/w nanoemulsions.

Development and Characterization of Gelled Double Emulsions Based on Chia (Salvia hispanica L.) Mucilage Mixed with Different Biopolymers and Loaded with Green Tea Extract (Camellia sinensis)

The aim of this research was to develop and characterize five gelled double emulsions based on chia mucilage (CM) and different biopolymers (κ-carrageenan, C; locust bean gum, L; thixogum, T; and whey protein concentrate, W) loaded with green tea extract (GTE). Gelled double emulsions consisted of W₁ (whey-protein-concentrate/sodium-azide/NaCl/GTE)/O and (PGPR/canola-oi)/W₂ (CM, CMC, CML, CMT and CMW), and were characterized based on physicochemical properties during 35 days of storage. Optical microscopy clearly showed the drops of the internal phase surrounded by droplets of oil dispersed in the second aqueous phase; the droplet size was higher for CMT and lowest for CMW. In addition, all emulsions were highly stable at creaming and were effective in reducing the loss of antioxidant activity (88.82%) and total phenols (64.26%) during storage; CMT, CML and CM were the most effective. Furthermore, all emulsions showed a protective effect by modulating the release of the GTE in a simulated gastrointestinal environment, allowing a controlled release during the gastric-intestinal digestion phases and reaching its maximum release in the intestinal phase (64.57–83.31%). Thus, gelled double emulsions are an alternative for the preservation of GTE and could be a potential alternative for their application in the development of functional foods.

Influence of Solvent Evaporation Technique Parameters on Diameter of Submicron Lamivudine-Poly-ε-Caprolactone Conjugate Particles

The size of active pharmaceutical ingredient carrier is one of the key properties considered during design of submicron drug delivery systems. Particle diameter may determine drug biodistribution, cellular uptake, and elimination path. Solvent evaporation technique is a flexible method of particle preparation, in which various macromolecules and drugs may be employed. Parameters of emulsion obtained as first step of particle preparation are crucial in terms of particle size, drug loading, and morphology. The aim of the study was to investigate the influence of emulsion preparation parameters on diameter of resulting particles. Impact of surfactant type and concentration, homogenization time, homogenization rate, phase ratio, and conjugate concentration were evaluated. Model drug lamivudine was covalently bound to polymer and applied in solvent evaporation method in order to overcome issues related to drug loading and provide method-independent incorporation. Synthesized drug-polymer conjugate and obtained particles were evaluated via dynamic light scattering, chromatography, scanning electron microscopy, and spectroscopic methods. Covalent bonding between drug and polymeric chain was confirmed, estimated drug content per milligram of conjugate was 19 μg. Among employed colloid stabilizer, poly(vinyl alcohol) was proven to be most effective. Homogenization rate and surfactant concentration were identified as crucial parameters in terms of particle diameter control.

Effect of In Vitro Digestion on Water-in-Oil-in-Water Emulsions Containing Anthocyanins from Grape Skin Powder

The effects of in vitro batch digestion on water-in-oil-in-water (W/O/W) double emulsions encapsulated with anthocyanins (ACNs) from grape skin were investigated. The double emulsions exhibited the monomodal distribution (d = 686 ± 25 nm) showing relatively high encapsulation efficiency (87.74 ± 3.12%). After in vitro mouth digestion, the droplet size (d = 771 ± 26 nm) was significantly increased (p < 0.05). The double W₁/O/W₂ emulsions became a single W₁/O emulsion due to proteolysis, which were coalesced together to form big particles with significant increases (p < 0.01) of average droplet sizes (d > 5 µm) after gastric digestion. During intestinal digestion, W₁/O droplets were broken to give empty oil droplets and released ACNs in inner water phase, and the average droplet sizes (d < 260 nm) decreased significantly (p < 0.05). Our results indicated that ACNs were effectively protected by W/O/W double emulsions against in vitro mouth digestion and gastric, and were delivered in the simulated small intestine phase.

Development and stability evaluation of water-in-edible oils emulsions formulated with the incorporation of hydrophilic Hibiscus sabdariffa extract

New functional oils (extra virgin olive oil, EVOO and sunflower oil, SO) containing antioxidants from Hibiscus sabdariffa extract were developed by W/O emulsion. Their physical and chemical stability was measured over time. The lowest coalescence rate was obtained with 8 and 12 wt% surfactant amount for EVOO and SO emulsions, respectively. Before the evaluation of the oxidative stability, an optimization of phenolic compounds extraction from emulsions by multi-response surface methodology was performed. EVOO emulsions were chemically more stable over time than SO emulsions in terms of total phenolic content (TPC), antioxidant activity and chemical composition measured by HPLC-ESI.TOF-MS. TPC significantly increased (from 2.02 ± 0.07 to 2.71 ± 0.06 mg Eq GAE/g extract) and the antioxidant activity measured by TEAC remained constant for 1 month of storage. Thus, W/O emulsion technology has proven to be a potential method to vehiculize and stabilize bioactive compounds from H. sabdariffa into edible oils.

Formulation and physiochemical study of α-tocopherol based oil in water nanoemulsion stabilized with non toxic, biodegradable surfactant: Sodium stearoyl lactate

The unique properties such as high optical clarity, stability and enhanced bioavailability of nanoemulsion make them useful for food, cosmetic and pharmaceutical industries. In this work, sodium stearoyl lactate and Tween 80 surfactants were collectively used to fabricate alpha tocopherol based oil in water nanoemulsion using high energy ultrasonication method. The spherical nature of pure and drug loaded nanoemulsion has been confirmed with transmission electron microscopy (TEM). The influence of pH, dilution, surfactant concentration and ionic strength on average particle size of pure and nutraceutical (benzylisothiocyanate and curcumin) encapsulated emulsion was examined. The prepared emulsion exhibited good stability up to 90days in salt solution (50-200mM) and different pH conditions. The cumulative release % of benzylisothiocyanate and curcumin was found to be 50.29% in 36h and 89.15% in 150h respectively. The antioxidant activity of pure, benzylisothiocyanate, curcumin and cocktail (benzylisothiocyanate and curcumin) nanoemulsion was calculated with 2,2-diphenyl-1-picrylhydrazyl radical. The IC₅₀ value of different antioxidant showed that benzylisothiocyanate nanoemulsion acted as better antioxidant as compared to pure and curcumin encapsulated nanoemulsion. Also the cell viability of pure nanoemulsion was found to be 24% on hep G2 cell. The effect of UV light irradiation on curcumin and benzylisothiocyanate stability was carried out in different solvent conditions (water/ethanol and nanoemulsion). The degradation of curcumin by the impact of UV light was successfully controlled by trapping in NEm.

Ultrasonic assisted formation and stability of mustard oil in water nanoemulsion: Effect of process parameters and their optimization

The present work reports the ultrasound assisted preparation of mustard oil in water nanoemulsion stabilized by Span 80 and Tween 80 at different operating conditions. Effects of various operating parameters such as HLB (Hydrophilic Lipophilic Balance) value, surfactant volume fraction (φ_S), oil volume fraction (φ_O) and power amplitude were investigated and optimized on the basis of droplet size and stability of nanoemulsions. It was observed that minimum droplet size of about 87.38nm was obtained within 30min of ultrasonication at an optimum HLB value of 10, φ_S of 0.08 (8%, v/v), φ_O of 0.1 (10%, v/v) and ultrasonic power amplitude of 40%. The stability of the nanoemulsion was measured through visual observation and it was found that the unstable emulsions got separated within 24h whereas, stable emulsions never showed any separation until 90days. In addition to that, the kinetic stability of the prepared nanoemulsions was also assessed under centrifuge and thermal stress conditions. The emulsion stability was found to be unaffected by these forces as the droplet size remained unchanged. The ultrasound prepared emulsion was found to be long term stable even after 3months of storage at ambient conditions without any visual evidence of creaming and phase separation and also remained kinetically stable. FTIR analysis of the emulsions at different sonication conditions was carried out to examine the possible impact of ultrasonically induced chemical effects on oil structure during emulsification and it was found that the oil molecular structure was unaffected by ultrasonication process. The present work illustrates the formation and stability of mustard oil in water nanoemulsion using ultrasound cavitation which may be useful in food and cosmetic based applications.

Colorimetry Technique as a Tool for Determining Release Kinetics and Mass Transfer Parameters of Anthocyanins Encapsulated in W1/O/W2 Double Emulsions

Anthocyanin extract (AE) was encapsulated in W1/O/W2 double emulsions and colorimetry technique using the CIE L*a*b* system was used to determine the release kinetics. Parameters a* and b* better correlated the variations in color of emulsions due to the release of AE into the external phase. Chroma value (C*) was used for tracking these color variations and to determine the release kinetics. The emulsions showed high stability, droplet sizes didn’t change after 30 days of storage (D4,3=4.74±0.12 μm), and 2.7 % AE was released to the external phase after this time. The possible release mechanism of AE from the internal phase of the emulsion is diffusion controlled with good accordance to Fick’s first law (R2=0.9938) with a diffusion coefficient of 7.15×10−8 cm2/d.

The research about microscopic structure of emulsion membrane in O/W emulsion by NMR and its influence to emulsion stability

PURPOSE

This paper discussed the influence of microstructure of emulsion membrane on O/W emulsion stability.

METHODS

O/W emulsions were emulsified with equal dosage of egg yolk lecithin and increasing dosage of co-emulsifier (oleic acid or HS15). The average particle size and centrifugal stability constant of emulsion, as well as interfacial tension between oil and water phase were determined. The microstructure of emulsion membrane had been studied by (1)H/(13)C NMR, meanwhile the emulsion droplets were visually presented with TEM and IFM.

RESULTS

With increasing dosage of co-emulsifier, emulsions showed two stable states, under which the signal intensity of characteristic group (orient to lipophilic core) of egg yolk lecithin disappeared in NMR of emulsions, but that (orient to aqueous phase) of co-emulsifiers only had some reduction at the second stable state. At the two stable states, the emulsion membranes were neater in TEM and emulsion droplets were rounder in IFM. Furthermore, the average particle size of emulsions at the second stable state was bigger than that at the first stable state.

CONCLUSIONS

Egg yolk lecithin and co-emulsifier respectively arranged into monolayer and bilayer emulsion membrane at the two stable states. The microstructure of emulsion membrane was related to the stability of emulsion.

Formulation, Pharmacokinetic, and Efficacy Studies of Mannosylated Self-Emulsifying Solid Dispersions of Noscapine

Purpose

To formulate hydroxypropyl methylcellulose-stabilized self-emulsifying solid dispersible carriers of noscapine to enhance oral bioavailability.

Methods

Formulation of noscapine (Nos) self-emulsifying solid dispersible microparticles (SESDs) was afforded by emulsification using an optimized formula of Labrafil M1944, Tween-80, and Labrasol followed by spray-drying with hydroxypropyl methylcellulose (HPMC), with and without mannosamine (Mann-Nos_SESDs and Nos_SESDs respectively); self-microemulsifying liquid dispersions (SMEDDs) with and without mannosamine (Mann-Nos_SMEDDs and Nos_SMEDDs respectively) were also prepared. SMEDDs and SESDs were characterized for size, polydispersity, surface charge, entrapment efficiency, in vitro permeability, in vitro release kinetics, and oral pharmacokinetics in Sprague-Dawley rats (10 mg/kg p.o). The antitumor efficacy of Mann-Nos_SESDs on the basis of chemosensitization to cisplatin (2.0 mg/kg, IV) was investigated in a chemorefractory lung tumor Nu/Nu mouse model up to a maximal oral dose of 300 mg/kg.

Results

The oil/surfactant/co-surfactant mixture of Labrafil M1944, Tween-80, and Labrasol optimized at weight ratios of 62.8:9.30:27.90% produced stable self-microemulsifying dispersions (SMEDDs) at a SMEDD to water ratio of 1–3:7–9 parts by weight. SMEDDs had hydrodynamic diameters between 231 and 246 nm; surface charges ranged from -16.50 to -18.7 mV; and entrapment efficiencies were between 32 and 35%. SESDs ranged in size between 5.84 and 6.60 μm with surface charges from -10.62 to -12.40 mV and entrapment efficiencies of 30.96±4.66 and 32.05±3.72% (Nos_SESDs and Mann-Nos_SESDs respectively). Mann-Nos_SESDs exhibited saturating uptake across Caco-2 monolayers (P_app = 4.94±0.18 × 10⁻⁶ cm/s), with controlled release of 50% of Nos in 6 hr at pH 6.8 following Higuchi kinetics. Mann-Nos_ SESDs was 40% more bioavailable compared to Nos_SESDs; and was effective in sensitizing H1650 SP cells to Cisplatin in vitro and in an orthotopic lung tumor model of H1650 SP origin.

Conclusions

Mannosylated noscapine self-emulsifying solid dispersions (Mann-Nos_SESDs) are bioavailable and potentiate the antineoplastic effect of cisplatin-based chemotherapy in cisplatin-resistant NSCLC.

Nanoparticles as drug carriers: current issues with in vitro testing

Incorporation of nanotechnology in the field of drug delivery has created exciting opportunities for the purposeful design of nanocarriers with potentials such as targeted delivery or controlled release of the incorporated cargo, improvement of bioavailability and reduction of therapeutic side-effects. Prior to in vivo administration, nanocarriers should undergo a set of in vitro evaluation procedures to ensure their stability, safety, conformity and ability to fulfill the desired mission. In this paper, current issues with in vitro evaluation techniques used for nanocarrier characterization (assessment of particle size, surface charge, drug release and toxicity) will be discussed. Furthermore, sufficiency of in vitro evaluation procedures for the prediction of in vivo scenarios and the necessary considerations to improve the correlation between the two settings will be debated.

Rosmarinus officinalis L. extract and some of its active ingredients as potential emulsion stabilizers: a new approach to the formation of multiple (W/O/W) emulsion

Nowadays, novel topical formulations loaded with natural functional actives are under intense investigations. Therefore, the aim of our study was to evaluate how the rosemary extract and some of its active ingredients [rosmarinic acid (RA), ursolic acid (UA) and oleanolic acid (OA)] affect technological characteristics of multiple emulsion. Formulation has been prepared by adding investigated solutions (10%) in water/oil/water (W/O/W) multiple emulsion consisting of different lipophilic phases: olive oil and liquid paraffin, with 0.5% emulsifying agent (complex of sodium polyacrylate and polysorbate 20) under constant stirring with mechanical stirrer at room temperature. The emulsion parameters were evaluated using centrifugation test, freeze-thaw cycle test, microscopical and texture analyses. Rosemary's triterpenic saponins UA and OA showed the highest emulsion stabilizing properties: they decreased CI from 3.26% to 10.23% (p < 0.05). According to obtained interfacial tension data, the effect of rosemary active ingredients is not surfactant-like. Even though emulsifier itself at low concentration intends to form directly the multiple emulsion, the obtained results indicate that rosemary extract containing active ingredients does not only serve as functional cosmetic agent due to a number of biological activities, but also offer potential advantages as a stabilizer and an enhancer of W/O/W emulsions formation for dermopharmaceutical and cosmetic preparations.

Topical microemulsion containing Punica granatum extract: its control over skin erythema and melanin in healthy Asian subjects

INTRODUCTION

Punica granatum is apotent source of polyphenolic compounds with strong free radicals scavenging activity. The skin lightening effects of Punica granatum are assumed due to ellagic acid which acts by chelating copper at the active site of tyrosinase.

AIM

To explore a topical microemulsion (O/W) of pomegranate (Punica granatum) extract for its control on skin erythema and melanin.

MATERIAL AND METHODS

Microemulsions were formulated using a polysorbate surfactant (Tween 80(®)) along with cosurfactant (propylene glycol) and were characterized regarding their stability. The placebo microemulsion (without extract) and the active microemulsion (containing Punica extract) were applied in a split face fashion by the volunteers (n = 11) for a period of 12 weeks. Skin erythema and melanin were measured at baseline and after every 15 days to determine any effect produced by these formulations.

RESULTS

Active formulation showed a significant impact on skin erythema and melanin (p < 0.05).

CONCLUSIONS

This study reveals that a suitable topical formulation like microemulsion could employ the Punica granatum extract for conditions where elevated skin melanin and erythema have significantly prone skin physiology.