Lower Droplet Size Research Articles

Removal of xylenol orange from its aqueous solution using SDS self-microemulsifying systems: optimization by Box–Behnken statistical design

The aim of present study was to develop and evaluate sodium dodecyl sulfate (SDS) self-microemulsifying systems (SMES) for the removal of an anionic dye xylenol orange (XO) from its bulk aqueous media via liquid-liquid adsorption. The composition of SDS SMES was optimized by Box-Behnken statistical design for the maximum removal of XO from its aqueous solution. Various SDS formulations were prepared by spontaneous emulsification method and characterized for thermodynamic stability, self-microemulsification efficiency, droplet size, and viscosity. Adsorption studies were conducted at 8, 16, and 24 h by mixing small amounts of SDS formulations with relatively large amounts of bulk aqueous solution of XO. Droplet size and viscosity of SDS formulations were significantly influenced by oil phase concentration (triacetin), while surfactant concentration had little impact on droplet size and viscosity. However, the percentage of removal of XO was influenced by triacetin concentration, surfactant concentration, and adsorption time. Based on lowest droplet size (35.97 nm), lowest viscosity (29.62 cp), and highest percentage of removal efficiency (89.77 %), formulation F14, containing 2 % w/w of triacetin and 40 % w/w of surfactant mixture (20 % w/w of SDS and 20 % w/w of polyethylene glycol 400), was selected as an optimized formulation for the removal of XO from its bulk aqueous media after 16 h. These results indicated that SDS SMES could be suitable alternates of solid-liquid adsorption for the removal of toxic dyes such as XO from its aqueous solution through liquid-liquid adsorption.

Enhanced Antibacterial Effects of Clove Essential Oil by Nanoemulsion

The aim of present study was to develop and evaluate nanoemulsion formulations of clove essential oil (CEO) for its antibacterial effects in comparison with pure CEO and standard amikacin antibiotic (positive control). Different nanoemulsions of CEO were developed by aqueous phase titration method via construction of pseudo-ternary phase diagrams and investigated for thermodynamic stability and self-nanoemulsification tests. Selected formulations (F1-F5) were characterized for droplet size distribution, viscosity, zeta potential, transmittance and surface morphology. Based on lowest droplet size (29.1 nm), lowest PI (0.026), lowest viscosity (34.6 cp), optimal zeta potential (-31.4 mV), highest transmittance (99.4 %) and lowest concentration of Triacetin (8 % w/w), CEO nanoemulsion F1 (containing 1 % w/w of CEO, 8 % w/w of Triacetin, 15 % w/w of Tween-80, 15 % w/w of Labrasol and 61 % w/w of water) was subjected to antibacterial studies in comparison with pure oil and standard amikacin. The antibacterial effects of F1 were found to be superior over pure oil against all bacterial strains investigated. However, the antibacterial effects of F1 were highly comparable with standard amikacin against all bacterial strains. The minimum inhibitory concentrations (MICs) of F1 were observed in the range of 0.075-0.300 % w/w as compared to pure oil (MICs 0.130-0.500 % w/w) and standard amikacin (MICs 2-16 μg/ml). These results indicated the potential of nanoemulsions for enhancing the therapeutic efficacy of natural bioactive ingredients such as CEO.

Impact of Mixed Nonionic Surfactants on Self-Nanoemulsification Efficiency of Sefsol-218 in Glibenclamide Nanoemulsion

The aim of present study was to evaluate the impact of various combinations of nonionic surfactants on selfnanoemulsification efficiency of Sefsol-218 in glibenclamide nanoemulsion. Surfactants Labrasol, HCO-60, Tween-80, Cremophor-EL and Gelucire-44/14 along with cosurfactants Transcutol-HP, isopropyl alcohol and ethanol were investigated for this purpose. Formulations were prepared by spontaneous emulsification method and subjected for thermodynamic stability and self-nanoemulsification test. Only those formulations which were found to be stable at various stress conditions of thermodynamic stability and selfnanoemulsification tests were further characterized in terms of droplet size, viscosity, refractive index and % transmittance. Formulations prepared with Labrasol or Gelucire-44/14 were found to be suitable for self-emulsifying drug delivery system only whereas those prepared using HCO-60, Tween-80 and Cremophor-EL were found to be suitable for self-nanoemulsifying drug delivery system or selfmicroemulsifying drug delivery system. Based on lowest droplet size (39.1 nm), optimal values of polydispersity index (0.292) & refractive index (1.332), lowest viscosity (34.3 cp) and highest % transmittance (99.6), formulation S23 (Sefsol-218/Cremophor- EL/ethanol/water) was optimized as best formulation for self-nanoemulsifying drug delivery system of glibenclamide. These results indicated that Cremophor-EL could be the best surfactant in terms of self-nanoemulsification.

Eugenol-loaded antimicrobial nanoemulsion preserves fruit juice against, microbial spoilage

Oil-in-water nanoemulsion was formulated using sesame oil, non-ionic surfactant (Tween20/Tween80) and water by ultrasound cavitation method. Development of nanoemulsion was optimized for process parameters such as surfactant type, surfactant concentration and emulsification time to obtain lower droplet diameter with greater stability. Increase in surfactant concentration and emulsification time resulted in nanoemulsion with minimized droplet diameter. Tween80 was more effective in reducing droplet size when compared to that of Tween20. Selected formulation with optimized process parameter (with oil-surfactant mixing ratio of 1:3 v/v and Tween80 as surfactant) was used for delivery of eugenol. Eugenol-loaded nanoemulsion was formulated with droplet diameter of 13nm and was stable for more than 1 month. Sesame oil blended eugenol-loaded nanoemulsion demonstrated lower droplet size and higher stability than only-eugenol (without sesame oil) nanoemulsion. Eugenol-loaded nanoemulsion S3E3 exhibited antibacterial activity against Staphylococcus aureus. Inactivation kinetics of S. aureus showed time and concentration killing of bacteria upon treatment with S3E3 nanoemulsion. Fluorescence microscopy results demonstrated that S3E3 nanoemulsion treatment resulted in alteration of membrane permeability. In situ assessment of S3E3 in orange juice exhibited a significant reduction in the native bacteria population.

Skin permeation of d-limonene-based nanoemulsions as a transdermal carrier prepared by ultrasonic emulsification

Nanoemulsions can be used for transporting pharmaceutical phytochemicals in skin-care products because of their stability and rapid permeation properties. However, droplet size may be a critical factor aiding permeation through skin and transdermal delivery efficiency. We prepared d-limonene nanoemulsions with various droplet sizes by ultrasonic emulsification using mixed surfactants of sorbitane trioleate and polyoxyethylene (20) oleyl ether under different hydrophilic–lipophilic balance (HLB) values. Droplet size decreased with increasing HLB value. With HLB 12, the droplet size was 23nm, and the encapsulated ratio peaked at 92.3%. Transmission electron microscopy revealed spherical droplets and the gray parts were d-limonene precipitation incorporated in spherical droplets of the emulsion system. Franz diffusion cell was used to evaluate the permeation of d-limonene nanoemulsion through rat abdominal skin; the permeation rate depended on droplet size. The emulsion with the lowest droplet size (54nm) achieved the maximum permeation rate. The concentration of d-limonene in the skin was 40.11μL/cm2 at the end of 360min. Histopathology revealed no distinct voids or empty spaces in the epidermal region of permeated rat skin, so the d-limonene nanoemulsion may be a safe carrier for transdermal drug delivery.

Transdermal delivery of diclofenac using water-in-oil microemulsion: formulation and mechanistic approach of drug skin permeation

The objective of the present investigation was to enhance skin permeation of diclofenac using water-in-oil microemulsion and to elucidate its skin permeation mechanism. The w/o microemulsion formulations were selected based on constructed pseudoternary phase diagrams depending on water solubilization capacity and thermodynamic stability. These formulations were also subjected to physical characterization based on droplet size, viscosity, pH and conductivity. Permeation of diclofenac across rat skin using side-by-side permeation cells from selected w/o microemulsion formulations were evaluated and compared with control formulations. The selected w/o microemulsion formulations were thermodynamically stable, and incorporation of diclofenac sodium into microemulsion did not affect the phase behavior of system. All microemulsion formulations had very low viscosity (11–17 cps) and droplet size range of 30–160 nm. Microemulsion formulations exhibited statistically significant increase in diclofenac permeation compared to oily solution, aqueous solution and oil–Smix solution. Higher skin permeation of diclofenac was observed with low Smix concentration and smaller droplet size. Increase in diclofenac loading in aqueous phase decreased the partition of diclofenac. Diclofenac from the oil phase of microemulsion could directly partition into skin, while diclofenac from the aqueous droplets was carried through skin by carrier effect.

Impact of various nonionic surfactants on self-nanoemulsification efficiency of two grades of Capryol (Capryol-90 and Capryol-PGMC)

The aim of present study was to investigate the impact of various combinations of nonionic surfactants on self-nanoemulsification efficiency of two grades of Capryol (Capryol-90 and Capryol-PGMC) in glibenclamide nanoemulsion. Labrasol, Gelucire-44/14, HCO-60, Tween-80 and Cremophor-EL were selected as surfactants and Transcutol-HP, isopropyl alcohol and ethanol were selected as cosurfactants. Various formulations (C1–C30) were prepared by spontaneous emulsification method and subjected to thermodynamic stability and self-nanoemulsification efficiency test. All these formulations were further characterized for droplet size distribution, viscosity, refractive index and % transmittance. Formulations prepared with Labrasol and Gelucire-44/14 were found to be suitable for self-emulsifying drug delivery system only whereas those prepared using Tween-80, HCO-60 and Cremophor-EL were found to be suitable for self-emulsifying or self-nanoemulsifying or self-microemulsifying drug delivery system of glibenclamide with respect to Capryol-90 or Capryol-PGMC. Based on visual assessment, thermodynamic stability, lowest droplet size (27.4nm), optimal values of polydispersity index (0.153) & refractive index (1.333), lowest viscosity (12.7cP) and highest % transmittance (99.6), formulation C30 (Capryol-PGMC/Cremophor-EL/ethanol/water) was optimized as best combination for self-nanoemulsifying drug delivery system of glibenclamide. These results indicated that Cremophor-EL could be the best surfactant in terms of self-nanoemulsification.

Synthesis of Porous Emulsion-Templated Monoliths Using a Low-Energy Emulsification Batch Mixer

Emulsion-templated porous monoliths based on castor oil-in-black liquor emulsions have been prepared using a low-energy emulsification technique. Lignins from black liquor polymerize in the continuous phase of the high internal phase emulsion to obtain highly microcellular materials with interconnected open porous structures. A two-step emulsification operating mode was developed in order to increase the maximum value of the castor-oil dispersed volume fraction obtained with the one-step emulsification mode (limited to 53 % of the total emulsion volume due to the very high viscosities of the fluids). A rheological study of the black liquor and of the prepared Medium Internal Phase Emulsions, have been conducted. Depending on the emulsification operating mode used, the morphology of the porous monoliths will differ. A rather low mean droplet size (about 6 μm) is obtained with the one-step mode, the two-step technique leads to a broader void size distribution and a further increase of added castor oil (up to 69 %) do not favor the homogeneity of the material.

The influence of different stabilizers and salt addition on the stability of model emulsions containing olive or sesame oil

Stabilizers are widely used in low-fat emulsion production. However, food industry pays attention to ingredients, such as resistant starch (RS) that also present substantial benefits to human health. Low-fat model emulsions of either olive or sesame oil that also contained xanthan gum (XG), whey protein concentrate (WPC), and undigested (resistant) starch (RS) were produced and stored at 5°C. Salt was added in selected samples. A multiple light scattering technique was applied for investigating destabilization phenomena. Microscopic observations and droplet size measurements took place. Rheological properties performing a heating–cooling cycle experiment (5–25–5°C) were measured. Olive oil emulsions presented the greatest stability and the lowest droplet size. RS plays the role of solid particle stabilizer, mainly entrapped in the matrix of the continuous phase. By salt addition stability was significantly improved, whereas droplet size was decreased. Those samples had a more pronounced elastic character and significantly greater viscosity values than their counterparts without salt.

Novel Self-Nanoemulsifying Drug Delivery Systems (SNEDDS) for Oral Delivery of Cinnarizine: Design, Optimization, and In-Vitro Assessment

Due to its extreme lipophilicity, the oral delivery of cinnarizine (CN) encounters several problems such as poor aqueous solubility and pH-dependent dissolution, which result in low and erratic bioavailability. The current study aims to design self-nanoemulsifying drug delivery systems (SNEDDS) of CN that circumvent such obstacles. Equilibrium solubility of CN was determined in a range of anhydrous and diluted lipid-based formulations. Dynamic dispersion tests were carried out to investigate the efficiency of drug release and magnitude of precipitation that could occur upon aqueous dilution. Droplet sizes of selected formulations, upon (1:1,000) aqueous dilution, were presented. The optimal formulations were enrolled in subsequent dissolution studies. The results showed that increasing lipid chain length and surfactant lipophilicity raised the formulation solvent capacity, while adding co-solvents provoked a negative influence. The inclusion of mixed glycerides and/or hydrophilic surfactants improved the drug release efficiency. Generally, no significant precipitation was observed upon aqueous dilution of the formulations. Five formulations were optimal in terms of their superior self-emulsifying efficiency, drug solubility, dispersion characteristics, and lower droplet size. Furthermore, the optimal formulations showed superior dissolution profile compared to the marketed (Stugeron®) tablet. Most importantly, they could resist the intensive precipitation observed with the marketed tablet upon shifting from acidic to alkaline media. However, SNEDDS containing medium-chain mixed glycerides showed the highest drug release rate and provide great potential to enhance the oral CN delivery. Accordingly, the lipid portion seems to be the most vital component in designing CN self-nanoemulsifying systems.

Emulsion Fuels Production between Diesel and Bio-Oil Middle Fraction from Molecular Distillation

In this paper, emulsification study on bio-oil middle fraction and diesel was carried out. Mechanical and ultrasound emulsification technologies were used to prepare emulsion fuels between bio-oil middle fraction and diesel with different hydrophile and lipophile balance (HLB) values. It was found that the stability curve of emulsions had two peaks corresponding to the HLB values of 4.3 and 6, respectively. Comparable to the mechanical emulsions, the ultrasound emulsions had longer stable time. The stable time for ultrasound emulsions at the HLB values of 4.3 and 6 were 215 minutes and 143 minutes, respectively. Then the effects of surface tension and droplet size distribution on the stability of emulsions were investigated. It was found that the emulsion fuels with lower surface tension and smaller droplet size had longer stable time.

Influence of soy protein's structural modifications on their microencapsulation properties: α-Tocopherol microparticle preparation

Enzymatic and chemical modifications of soy protein isolate (SPI) were studied in order to improve SPI properties for their use as wall material for α-tocopherol microencapsulation by spray-drying. The structural modifications of SPI by enzymatic hydrolysis and/or N-acylation were carried out in aqueous media without any use of organic solvent neither surfactant. Emulsions from aqueous solutions of native or modified SPI and hydrophobic α-tocopherol, were prepared and spray-dried to produce α-tocopherol microparticles. The effect of protein modifications and the influence of the core/shell ratio on both emulsion and microparticle properties were characterized. The obtained results demonstrated that oil-in-water emulsions prepared with modified proteins had lower droplet size (0.5–0.9μm) and viscosity (3.6–14.8mPa⋅s) compared to those prepared with native proteins (1.1μm and 15.0mPa⋅s respectively). Efficiency of oil retention decreased after protein hydrolysis from 79.7 to 38.9%, but the grafting of hydrophobic chain by acylation improved efficiency of α-tocopherol retention up to 94.8%. Moreover, higher emulsion viscosity, particle size and process efficiency were observed with the increase of α-tocopherol amount.

The Studies of Phase Equilibria and Efficiency Assessment for Self-Emulsifying Lipid-Based Formulations

The study was designed to build up a database for the evaluation of the self-emulsifying lipid formulations performance. A standard assessment method was constructed to evaluate the self-emulsifying efficiency of the formulations based on five parameters including excipients miscibility, spontaneity, dispersibility, homogeneity, and physical appearance. Equilibrium phase studies were conducted to investigate the phase changes of the anhydrous formulation in response to aqueous dilution. Droplet size studies were carried out to assess the influence of lipid and surfactant portions on the resulted droplet size upon aqueous dilution. Formulations containing mixed glycerides showed enhanced self-emulsification with both lipophilic and hydrophilic surfactants. Increasing the polarity of the lipid portion in the formulation leaded to progressive water solubilization capacity. In addition, formulations containing medium chain mixed glycerides and hydrophilic surfactants showed lower droplet size compared with their long chain and lipophilic counterparts. The inclusion of mixed glycerides in the lipid formulations enormously enhances the formulation efficiency.

Development and validation of HPLC method for simultaneous estimation of piperine and guggulsterones in compound Unani formulation (tablets) and a nanoreservoir system

An attempt has been made to develop and validate a simultaneous HPLC method for novel approach of drug release via oil-in-water (o/w) nanoemulsion formulation and Habb-e-Khardal Unani tablet containing piperine and guggul sterones E and Z as main ingredients. Nanoemulsion was prepared by titration method using sefsol-218 as an oily phase, cremophor-EL as a surfactant, transcutol as a co-surfactant and distilled water as an aqueous phase. The formulation was optimized on the basis of thermodynamic stability and dispersibilty test. The nanoformulation was evaluated for particle size, surface morphology, electrical conductivity and viscosity determination. The in vitro dissolution was carried out by dialysis bag method. Drugs were quantified using an HPLC method developed in-house with a C(18) column as stationary phase and acetonitrile and water as mobile phase at λ(max) of 240 nm. The optimized formulation showed higher drug release, lower droplet size and less viscosity as compared with the conventional Habb-e-Khardal Unani tablet. The present study illustrated the potential of nanoemulsion dosage form in improving biopharmaceutic performance of piperine and guggul sterone. The HPLC method was also found to be quite sufficient for the routine quality control of formulations containing piperine and guggul sterone E and Z as ingredients and also for in vitro drug release studies.

Crystallisation behaviour of palm oil nanoemulsions carrying vitamin E

Four emulsions were prepared using high pressure homogenisation at 300 or 1200 bar and aqueous phases containing 4.5 wt% whey proteins in mixture with 20 wt% palm oil (PO), alone (E300 and E1200), or in which 20 wt% PO was replaced by vitamin (EV300, EV1200). Thermal behaviour of bulk fat and emulsions in the absence or presence of vitamin, as monitored by differential scanning calorimetry (DSC), indicated that fat crystallisation in supercooled melt was delayed in bulk fat in the presence of vitamin and more delayed in emulsions with lower droplet sizes and containing vitamin. These results were supported by (i) isothermal DSC experiments where exothermic peaks occurred at higher holding times and (ii) dynamic DSC experiments which showed lower melting reactions in emulsions with lower droplet sizes and containing vitamin. Synchrotron X-ray scattering measurements performed simultaneously at small and wide angles on fat samples stored at 4 °C for 12 h showed co-existence of 2L and 3L longitudinal stacking in bulk fat without vitamin, and only 2L organisation of TAGs in the presence of vitamin. Trends in the proportions of α,β′, β lateral packing in lipid droplets were also observed to be more affected by the presence of vitamin rather than their size, indicating a higher rate of α → β′ → β polymorphic transformations in the presence of vitamin. Combining data obtained from DSC and X-Ray signals showed that lipid droplets with lower solid fat content, of which a higher proportion of β polymporphs, were those presenting lower size and lower ability for vitamin protection against chemical degradation, which is of great interest for formulation of lipid nanoparticles as bioactive matrix carriers.

Design and Development of Oral Oil-in-Water Nanoemulsion Formulation Bearing Atorvastatin: In Vitro Assessment

The objective of the present investigation was to design a thermodynamically stable and dilutable nanoemulsion formulation of AT-Ca with minimum surfactant concentration that could improve its solubility as well as its oral bioavailability. The composition of optimized nanoemulsion formulation was Sefsol 218 and oleic acid (1:1) 10% w/w, as an oil phase, Tween-20 (19% w/w) as a surfactant, Carbitol (19% w/w) as a cosurfactant and distilled water (52% w/w) as an aqueous phase, containing 10 mg of AT. The optimized formulation showed higher% drug release (99.34%), lower droplet size (42.8 ± 0.42 nm) with low polydispersity index (0.237 ± 0.012), less viscosity (27.51 ± 1.01 cP) and infinite dilution capability. In vitro drug release from the nanoemulsion formulations was highly significant (p < 0.01) as compared to drug suspension.

Metal transfer characteristics of rotating arc narrow gap horizontal GMAW

The metal transfer process in rotating arc narrow gap horizontal welding is successfully observed by the high speed photography system. Because of the difference of the arc length induced by the molten pool surface shape in the rotating arc horizontal welding, the metal transfer has certain change regularity. In the weld width direction, the transfer frequency in the area of near both sidewalls is larger than that in the centre of the groove. In a rotating period, the transfer frequency in the downward motion process is larger than that in the upward motion process. The rotating arc process can improve the metal transfer. The results indicated that the centrifugal force induced by the arc rotating has great effect on the globular transfer mode which has lower transfer frequency and larger droplet size. Regarding the spray transfer mode, it has limited effect.

Rheology and droplet size distribution of emulsions stabilized by crayfish flour

Highly concentrated oil-in-water (o/w) emulsions stabilized by crayfish flour at high pH were characterized by means of linear dynamic viscoelasticity and droplet size distribution (DSD) analysis. Power consumption and temperature were recorded as a function of emulsification time at different agitation speeds. The emulsions studied followed a gel-like behavior, characterized by G′ being about one order of magnitude higher than G″ within the experimental frequency range. This behavior was characteristic of highly concentrated emulsions with a well-developed plateau region. Increase in both energy input and crayfish flour concentration yielded higher values of linear viscoelasticity functions and lower droplet size, which suggested an enhancement of the elastic network and an increase in emulsion stability. The evolution of plateau modulus and Sauter diameter was studied at different concentrations of crayfish flour (0.25–6.25 wt%) over storage time at 5 °C. The microstructure of these emulsions was characterized by using confocal laser scanning microscopy (CLSM).

FLAMMABILITY OF AEROSOLS GENERATED BY A ROTARY ATOMIZER

Flammability of aerosols of hydrocarbon liquids was studied using a spinning disk atomizer, which simulates accidental aerosolization of a fuel from an aircraft. We determined the critical droplet sizes and fuel flow rates (or mass flux) needed to create an aerosol mixture that forms a stable flame upon ignition. At lower droplet sizes or higher flow rates than the critical values the aerosol mixtures were flammable. The critical flow rate increases with the droplet size for JP5 and are lower by a factor of 3 to 5 for heptane. The flammability diagram enables a quantitative comparison of different liquids in aerosol form. This is significantly different from the thermodynamic behavior of a liquid pool, which is dictated by the flash point or vapor pressure.

An investigation into the characteristics and drug release properties of multiple W/O/W emulsion systems containing low concentration of lipophilic polymeric emulsifier

Multiple W/O/W emulsions with high content of inner phase (Φ1 = Φ2 = 0.8) were prepared using relatively low concentrations of lipophilic polymeric primary emulsifier, PEG 30-dipolyhydroxystearate, and diclofenac diethylamine (DDA) as a model drug. The investigated formulations were characterized and their stability over the time was evaluated by dynamic and oscillatory rheological measurements, microscopic analysis and in vitro drug release study. In vitro release profiles of the selected model drug were evaluated in terms of the effective diffusion coefficients and flux of the released drug. The multiple emulsion samples exhibited good stability during the ageing time. Concentration of the lipophilic primary emulsifier markedly affected rheological behaviour as well as the droplet size and in vitro drug release kinetics of the investigated systems. The multiple emulsion systems with highest concentration (2.4%, w/w) of the primary emulsifier had the lowest droplet size and the highest apparent viscosity and highest elastic characteristics. Drug release data indicated predominately diffusional drug release mechanism with sustained and prolonged drug release accomplished with 2.4% (w/w) of lipophilic emulsifier employed.