Impact of process parameters in the generation of novel aspirin nanoemulsions--comparative studies between ultrasound cavitation and microfluidizer

Study of curcumin antioxidant activities in robust oil–water nanoemulsions

Symbolic representation of increased interactions from oil to CLFs, indicatedviaenhancedρandu.

Kinetics of the Change in Droplet Size during Nanoemulsion Formation

The evolution of droplet size during nanoemulsion formation is critical for the rational design of nanoemulsions in areas such as drug delivery and materials synthesis. In this article, we discuss the relative importance of various time scales involved in nanoemulsion formation and propose a population balance model for droplet breakup that takes into account the droplet's internal viscosity. The proposed model gives a qualitative agreement between average droplet size and polydispersity data for nanoemulsions prepared by high-pressure homogenization and ultrasonication. On the basis of these modeling results, we propose a correlation to obtain a parity plot for the droplet size data. We show that our model and correlation also work well with data from the existing literature. The proposed model and correlation can be used to guide future population balance studies and experimental preparation of nanoemulsions.

Statistical Analysis of Optimal Ultrasound Emulsification Parameters in Thistle-Oil Nanoemulsions

Thistle oil (INCI: Silybum marianum seed oil) is known as an anti-oxidant, moisturizing and skin regenerating cosmetic raw material. Nanoemulsions are a new form of cosmetic product showing very good user properties (ease of spreading over the skin with no greasy feeling). Moreover, due to their structure, they can also transport both hydrophilic and hydrophobic active substances to the skin. The aim of this work was the preparation and characterization of nanoemulsions, based on thistle oil. The non-ionic surfactants polysorbate 80 (PEG-20 sorbitan monooleate), decyl glucoside, and a polyglyceryl-4 ester blend were applied to stabilize the nanosystems. All formulations were obtained by a high energy method, using an ultrasonic device (Labsonic U, an ultrasound homogenizer). Variations in the emulsification parameters were tested, including surfactants concentration, pre-emulsification time, ultrasound power and sonication time. On the basis of statistical analysis (experimental design, cluster analysis, classification and regression trees) the best emulsification process parameters were determined. In order to verify the results of statistical analysis, once more an experimental study was conducted. The results obtained confirmed that statistical analysis can be a useful method in determining the conditions for obtaining stable nanoemulsions with desired properties. Formulations obtained with the use of Silybum marianum seed oil were characterized by long-term stability, a low polydispersity index, low viscosity and an average droplet size less than 200 nm.

Optimization of ultrasound induced emulsification on the formulation of palm-olein based nanoemulsions for the incorporation of antioxidant β-D-glucan polysaccharides

Polysaccharides of β-D-glucan configuration have well-known antioxidant activity against reactive free radicals generated from the oxidation of metabolic processes. In this study, β-D-glucan-polysaccharides extracted from Ganoderma lucidum were incorporated in palm olein based nanoemulsions which act as carrier systems to enhance the delivery and bioactivity of these polysaccharides and could be potentially useful for skin care applications. Initially response surface statistical design (Central Composite Design--CCD) was subjected to optimize the formulation variables of oil-in-water (O/W) nanoemulsions induced by ultrasound. The optimal formulation variables as predicted by CCD resulted in considerably improving the physical characteristics of ultrasonically formulated nanoemulsions by minimizing their droplet size, polydispersity index and viscosity. Moreover, the β-D-glucan-loaded nanoemulsions exhibited good stability over 90 days under different storage conditions (4 °C and 25 °C). The studies using palm olein based β-D-glucan-loaded nanoemulsion generated using ultrasound confirm higher antioxidant activity as compared to free β-D-glucan.

Ultrasonic emulsification of parenteral valproic acid-loaded nanoemulsion with response surface methodology and evaluation of its stability

Response surface methodology (RSM) was used to optimize the formulation of a nanoemulsion for central delivery following parenteral administration. A mixture of medium-chain triglyceride (MCT) and safflower seed oil (SSO) was determined as a sole phase from the emulsification properties. Similarly, a natural surfactant (lecithin) and non-ionic surfactant (Tween 80) (ratio 1:2) were used in the formulation. A central composite design (CCD) with three-factor at five-levels was used to optimize the processing method of high energy ultrasonicator. Effects of pre-sonication ultrasonic intensity (A), sonication time (B), and temperature (C) were studied on the preparation of nanoemulsion loaded with valproic acid. Influence of the aforementioned specifically the effects of the ultrasonic processing parameters on droplet size and polydispersity index were investigated. From the analysis, it was found that the interaction between ultrasonic intensity and sonication time was the most influential factor on the droplet size of nanoemulsion formulated. Ultrasonic intensity (A) significantly affects the polydispersity index value. With this optimization method, a favorable droplet size of a nanoemulsion with reasonable polydispersity index was able to be formulated within a short sonication time. A valproic acid loaded nanoemulsion can be obtained with 60% power intensity for 15 min at 60 °C. Droplet size of 43.21±0.11 nm with polydispersity index of 0.211 were produced. The drug content was then increased to 1.5%. Stability study of nanoemulsion containing 1.5% of valproic acid had a good stability as there are no significant changes in physicochemical aspects such as droplet size and polydispersity index. With the characteristisation study of pH, viscosity, transmission electron microscope (TEM) and stability assessment study the formulated nanoemulsion has the potential to penetrate blood-brain barrier in the treatment of epilepsy.

Controlling and predicting droplet size of nanoemulsions: scaling relations with experimental validation

Nanoemulsions possess powerful nano-scale properties that make them attractive for diverse applications such as drug delivery, food supplements, nanoparticle synthesis and pharmaceutical formulation. However, there is little knowledge in nanoemulsion literature about controlling and predicting droplet size. In this article, we propose a scaling relation to predict the dependence of nanoemulsion droplet size with physical properties such as viscosity of the droplet phase and continuous phase, and process parameters such as input power density. We validate our proposed scaling with a wide range of droplet size data from nanoemulsions prepared with high pressure homogenization and ultrasonication. Our proposed scaling also compares favorably with experimental data from literature. The scaling relation can serve as a guiding principle for rational design of nanoemulsions.

Nanoemulsion as a topical delivery system of antipsoriatic drugs

Nanoemulsion as a potential enhancer for the treatment of psoriasis.

Production of Nanoemulsions from Palm-Based Tocotrienol Rich Fraction by Microfluidization

In the present study, tocotrienol rich fraction (TRF) nanoemulsions were produced as an alternative approach to improve solubility and absorption of tocotrienols. In the present study, droplet size obtained after 10 cycles of homogenization with increasing pressure was found to decrease from 120 to 65.1 nm. Nanoemulsions stabilized with Tween series alone or emulsifier blend Brij 35:Span 80 (0.6:0.4 w/w) homogenized at 25,000 psi and 10 cycles, produced droplet size less than 100 nm and a narrow size distribution with a polydispersity index (PDI) value lower than 0.2. However blend of Tween series with Span 80 produced nanoemulsions with droplet size larger than 200 nm. This work has also demonstrated the amount of tocols losses in TRF nanoemulsion stabilized Tweens alone or emulsifier blend Brij 35:Span 80 (0.6:0.4 w/w) ranged between 3%-25%. This can be attributed to the interfacial film formed surrounding the droplets exhibited different level of oxidative stability against heat and free radicals created during high pressure emulsification.

Nanoemulsions as an effective medium for encapsulation and stabilization of cholesterol/β-cyclodextrin inclusion complex

BACKGROUND

Inclusion complex formation between β-cyclodextrin (β-CD) and suitable guest molecules such as cholesterol (Ch) has regularly been exploited to design self-assembled structures. In the present study an effective nanoemulsion medium (lecithin/Tween 80/ethyl oleate/water) was selected for solubilizing and stabilizing Ch and Ch/β-CD inclusion complex. Phase solubility, spectroscopic, thermodynamic, Z-average diameter and morphological analyses were conducted.

RESULTS

Phase solubility data analysis demonstrated an increase in Ch solubility at low β-CD concentrations (0.01-0.35 mmol L(-1) ). Transmission electron microscopy and Z-average diameter data indicated the spherical nature of the droplets and confirmed the formation of nanoemulsions with an average size of less than 50 nm. The negative value of ΔG obtained during analysis further indicated that the binding was spontaneous in nature.

CONCLUSION

Primarily, this research demonstrates the use of nanoemulsions as a medium in food matrices, instead of water, for hosting Ch in β-CD.

Preparation of betulinic acid nanoemulsions stabilized by ω-3 enriched phosphatidylcholine

Bioactive compounds such as ω-3 fatty acids and terpenes, have been associated with beneficial health effects; however, their solubility in the gastrointestinal tract and its bioavailability in the body are low. Nanoemulsions offer a viable alternative to disperse lipophilic compounds and improve their dissolution, permeation, absorption and bioavailability. Enzyme modified phosphatidylcholine (PC) with ω-3 fatty acids was used as emulsifier to stabilize oil-in-water nanoemulsions generated using ultrasound device. These systems were used as carriers of betulinic acid, which has reported anti-carcinogenic activity. Phospholipase-catalyzed modification of PC allowed the incorporation of 50 mol% of ω-3 fatty acids. Formation variables such as oil type and ultrasound amplitude had effects on nanoemulsion characteristics. Incorporation of betulinic acid affected globule size; however, betulinic acid nanoemulsions below 200 nm could be prepared. The conditions under which betulinic acid nanoemulsions were obtained using the modified phosphatidylcholine with the smaller globule size (91 nm) were 10% PC, 25% glycerol, medium chain oil and 30% amplitude for 12 min in the sonicator. Storage temperature had an effect on the stability of the nanoemulsions, at 5°C we observed the smallest growth in globule size. The use of olive oil decreased the globule size growth during storage of the nanoemulsion stabilized with modified phosphatidylcholine, although globule size obtained was greater than 200 nm. Medium pH had a significant effect on the nanoemulsions; alkaline pH values improved storage stability. These results provide useful information for using this type of carrier system on the formulation of products in the pharmaceutical or food industry.

Ultrasound assisted synthesis of PANI/ZnMoO4 nanocomposite for simultaneous improvement in anticorrosion, physico-chemical properties and its application in gas sensing

Ultrasound assisted in-situ semi-batch emulsion polymerization has been used for the preparation of polyaniline (PANI) and PANI/ZnMoO4 nanocomposite with different loading of ZnMoO4 (ZM) nanoparticles. ZM nanoparticles were functionalized using Myristic acid (MA) for better compatibility with PANI. The cavitational effects induced due to ultrasonic irradiations have been shown significant enhancement in the dispersion of functionalized ZM nanoparticles into the PANI during ultrasound assisted in-situ emulsion polymerization process. TEM images of PANI/ZM nanocomposite particles give the direct evidence of fine dispersion and encapsulation of MA treated ZM nanoparticles in PANI matrix. The presence of ZM nanoparticles in PANI/ZM nanocomposite shows significant improvement in the mechanical (cross-cut adhesion), thermal, anticorrosion and sensing properties of PANI/ZM nanocomposite/alkyd coatings over PANI/alkyd and neat alkyd resin coating. Fine and uniform dispersion of ZM nanoparticles in PANI matrix using this novel synthesis method (PANI (p-type)/ZM (n-type) hetero-junction) improves LPG sensing ability and minimizes response time to sense LPG significantly compared with neat PANI.

Nanoengineered drug delivery systems for enhancing antibiotic therapy

Formulation scientists are recognizing nanoengineered drug delivery systems as an effective strategy to overcome limitations associated with antibiotic drug therapy. Antibiotics encapsulated into nanodelivery systems will contribute to improved management of patients with various infectious diseases and to overcoming the serious global burden of antibiotic resistance. An extensive review of several antibiotic-loaded nanocarriers that have been formulated to target drugs to infectious sites, achieve controlled drug release profiles, and address formulation challenges, such as low-drug entrapment efficiencies, poor solubility and stability is presented in this paper. The physicochemical properties and the in vitro/in vivo performances of various antibiotic-loaded delivery systems, such as polymeric nanoparticles, micelles, dendrimers, liposomes, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles, nanohybirds, nanofibers/scaffolds, nanosheets, nanoplexes, and nanotubes/horn/rods and nanoemulsions, are highlighted and evaluated. Future studies that will be essential to optimize formulation and commercialization of these antibiotic-loaded nanosystems are also identified. The review presented emphasizes the significant formulation progress achieved and potential that novel nanoengineered antibiotic drug delivery systems have for enhancing the treatment of patients with a range of infections.

Cavitation technology - a greener processing technique for the generation of pharmaceutical nanoemulsions

Novel nanoemulsion-based drug delivery systems (DDS) have been proposed as alternative and effective approach for the delivery of various types of poorly water-soluble drugs in the last decade. This nanoformulation strategy significantly improves the cell uptake and bioavailability of numerous hydrophobic drugs by increasing their solubility and dissolution rate, maintaining drug concentration within the therapeutic range by controlling the drug release rate, and reducing systemic side effects by targeting to specific disease site, thus offering a better patient compliance. To date, cavitation technology has emerged to be an energy-efficient and promising technique to generate such nanoscale emulsions encapsulating a variety of highly potent pharmaceutical agents that are water-insoluble. The micro-turbulent implosions of cavitation bubbles tear-off primary giant oily emulsion droplets to nano-scale, spontaneously leading to the formation of highly uniform drug contained nanodroplets. A substantial body of recent literatures in the field of nanoemulsions suggests that cavitation is a facile, cost-reducing yet safer generation tool, remarkably highlighting its industrial commercial viability in the development of designing novel nanocarriers or enhancing the properties of existing pharmaceutical products. In this review, the fundamentals of nanoemulsion and the principles involved in their formation are presented. The underlying mechanisms in the generation of pharmaceutical nanoemulsion under acoustic field as well as the advantages of using cavitation compared to the conventional techniques are also highlighted. This review focuses on recent nanoemulsion-based DDS development and how cavitation through ultrasound and hydrodynamic means is useful to generate the pharmaceutical grade nanoemulsions including the complex double or submicron multiple emulsions.

The stimuli-response characters of hydrogels prepared using ultrasound

The present work was an attempt to investigate the parameters that can affect the process of hydrogel formation in the presence of ultrasound. These parameters were concentrations of the reactants, the reaction medium, and acoustic factors. The monomers were acrylic acid and acrylamide, and the cross-linker was methylene bis acrylamide. Pulsed power ultrasound was irradiated to the reaction mixture from the tip of a probe unit. The swelling behaviors of the obtained hydrogels were investigated in various buffer solutions, at different temperature values, and using different ionic salts. The results show that ultrasonic irradiation significantly reduces reaction time and increases efficiency. Additionally, increasing glycerol in the solution changes the viscosity of the reaction for the better and increases the reaction rate. However, ionic strength and pH were not significantly effective in this respect. Another major finding was that increasing ultrasonic power and pulse hastens the reaction. Cationic salts were effective in this order: Na+>Ca2+>Fe3+. The hydrogel was responsive to pH, temperature, and salts. These findings provide a better understanding of hydrogel synthesis and enable us to control the pertinent parameters.

Edible films from methylcellulose and nanoemulsions of clove bud (Syzygium aromaticum) and oregano (Origanum vulgare) essential oils as shelf life extenders for sliced bread

Consumers are increasingly demanding foods with lower synthetic preservatives. Plant essential oils are natural compounds with remarkable antimicrobial properties and may be incorporated as emulsions into water-soluble polymers to form antimicrobial films. Coarse emulsions (diameters of 1.3-1.9 μm) and nanoemulsions (diameters of 180-250 nm) of clove bud (Syzygium aromaticum) and oregano (Origanum vulgare) essential oils were produced through low-speed mixing and ultrasonication, respectively. Methylcellulose was added for film-forming purposes. Both essential oils reduced the rigidity and increased the extensibility of the methylcellulose films, effects that were even more pronounced for nanodroplets. Both essential oils lessened the counts of yeasts and molds in sliced bread during 15 days, and droplet size reduction provided a further improvement in antimicrobial properties. Due to increased bioavailability, less preservative content might be used and still deliver the same antimicrobial efficiency if encapsulated in smaller particles.

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

Background and aims

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

Methods

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

Results

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

Conclusion

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

Emulsification by high frequency ultrasound using piezoelectric transducer: formation and stability of emulsifier free emulsion

Emulsifier free emulsion was developed with a new patented technique for food and cosmetic applications. This emulsification process dispersed oil droplets in water without any emulsifier. Emulsions were prepared with different vegetable oil ratios 5%, 10% and 15% (v/v) using high frequency ultrasounds generated by piezoelectric ceramic transducer vibrating at 1.7 MHz. The emulsion was prepared with various emulsification times between 0 and 10h. Oil droplets size was measured by laser granulometry. The pH variation was monitored; electrophoretic mobility and conductivity variation were measured using Zêtasizer equipment during emulsification process. The results revealed that oil droplets average size decreased significantly (p<0.05) during the first 6h of emulsification process and that from 160 to 1 μm for emulsions with 5%, 10% and from 400 to 29 μm for emulsion with 15% of initial oil ratio. For all tested oil ratios, pH measurement showed significant decrease and negative electrophoretic mobility showed the accumulation of OH(-) at oil/water interface leading to droplets stability in the emulsion. The conductivity of emulsions showed a decrease of the ions quantity in solution, which indicated formation of positive charge layer around OH(-) structure. They constitute a double ionic layer around oil particles providing emulsion stability. This study showed a strong correlation between turbidity measurement and proportion of emulsified oil.

Improved glycation after ultrasonic pretreatment revealed by high-performance liquid chromatography-linear ion trap/Orbitrap high-resolution mass spectrometry

The glycation extent of bovine serum albumin (BSA) before and after ultrasonication was evaluated by MALDI-TOF and Orbitrap mass spectrometry. Ultrasonic pretreatment significantly improved the incorporation of galactose to BSA. Prior to ultrasonic pretreatment, only 12 sites (11 lysines and 1 arginine) were glycated, whereas the number of glycation sites was increased to 42, including 39 lysines and 3 arginines, after treatment. Average degree of substitution per peptide molecule of BSA (DSP) was used to evaluate the glycation level for each glycation site. The ultrasonic pretreatment significantly improved the DSP value of all glycation sites. The prevalently promoted glycation by ultrasonic pretreatment suggests that ultrasonication improves glycation through altering the structure of BSA throughout all three domains. An ultrahigh-resolution linear ion trap Orbitrap mass spectrometer facilitates unambiguous localization of glycation sites, allowing an in-depth analysis of the nature and extent of protein glycation at the molecular level. High-intensity ultrasonication can greatly improve protein glycation and, therefore, opens new routes to modify the functionality of proteins in a positive way.

Nanoemulsion-based oral delivery systems for lipophilic bioactive components: nutraceuticals and pharmaceuticals

Nanoemulsions have considerable potential for encapsulating, protecting and delivering lipophilic bioactive components via the oral route, such as pharmaceuticals (drugs) and nutraceuticals (food components with specific health benefits). These systems can be fabricated from generally recognized as safe ingredients using relatively simple processing operations, such as mixing and homogenization. Some of the potential advantages of nanoemulsions over conventional emulsions include higher bioaccessibility, higher physical stability and higher optical clarity. An overview of the current status of nanoemulsion fabrication, stability, properties and biological fate is given, with special emphasis on the suitability of nanoemulsions for the oral delivery of hydrophobic bioactive components, such as drugs and nutraceuticals.

Stability of nanosuspensions in drug delivery

Nanosuspensions are nanosized colloidal dispersion systems that are stabilized by surfactants and/or polymers. Because nanosizing results in the creation of new interfaces and in a positive Gibbs free energy change, nanosuspensions are thermodynamically unstable systems with a tendency toward agglomeration or crystal growth. Despite extensive research on nanosuspension technology, stability remains a limitation for pharmaceutical or industrial applications of nanosuspensions. Furthermore, the empirical relationship between stabilizer efficacy and nanosuspension stability has not been well characterized. This review focuses on the issue of nanosuspension stability in drug delivery to present the state of the art of nanosuspensions. Therefore, this review will discuss unstable suspensions, methods and guidelines for selecting and optimizing stabilizers, approaches for enhancing stability, and other factors that influence nanosuspension stability. This review could serve as a reference for the educated selection of a stabilizer for a specific drug candidate and the optimization of the operational parameters for nanosuspension formulation, rather than the currently practiced trial-and-error approach.

Nanoemulsified orlistat-embedded multi-unit pellet system (MUPS) with improved dissolution and pancreatic lipase inhibition

The present research work explores an innovative technological solution to constraints in efficient oral delivery of poorly water-soluble anti-obesity drug orlistat. Nanoemulsion of orlistat and its subsequent transformation into multi-unit pellet system (MUPS) for improved oral delivery was developed. Orlistat nanoemulsion was developed with capryol PGMC as an oil phase and cremophor RH40 as an emulsifier using high-pressure homogenization. Influence of critical processing parameters on globule size distribution, polydispersity index and physical stability of nanoemulsion was evaluated. The optimized nanoemulsion was transformed into MUPS using an extrusion spheronization technique. Optimized formulation was characterized at nanoemulsion as well as MUPS stage. DLS and nanoparticle tracking analysis studies of orlistat nanoemulsion exhibited unimodal size distribution with polydispersity value <0.1. Confocal laser scanning microscopy (CLSM) studies confirmed the presence of uniform spherical nanosized oil droplets of nanoemulsified orlistat. DSC and PXRD studies of MUPS confirmed amorphization of embedded nanoemulsified orlistat. In-vitro dissolution studies in surfactant-reduced media demonstrated remarkable improvement in dissolution compared to pure orlistat and marketed formulation (Xenical Capsules 120 mg, Hoffman-La Roche, Basle, Switzerland). Comparative in-vitro bovine porcine pancreatic lipase inhibition studies of pure orlistat, marketed product and developed MUPS showed 13.57- and 2.41-fold higher lipase inhibition with developed MUPS compared to pure orlistat and marketed products, respectively.