Whey Protein/Polysaccharide-Stabilized Oil Powders for Topical Application—Release and Transdermal Delivery of Salicylic Acid from Oil Powders Compared to Redispersed Powders

Oil-in-water (o/w) emulsions are commonly converted into solid-like powders in order to improve their physical and chemical stabilities. The aim of this study was to investigate whether whey protein/polysaccharide-stabilized o/w emulsions could be converted into stable oil powders by means of freeze-drying. Moreover, during this study, the effects of pH and polymer type on release and trans(dermal) delivery of salicylic acid, a model drug, from these oil powders were investigated and compared to those of the respective template emulsions and redispersed oil powders. Physical characterization of the various formulations was performed, such as droplet size analysis and oil leakage, and relationships drawn with regards to release and trans(dermal) delivery. The experimental outcomes revealed that the oil powders could be redispersed in water without changing the release characteristics of salicylic acid. pH and polymer type affected the release of salicylic acid from the oil powders, template emulsions, and redispersed powders similarly. Contrary, the transdermal delivery from the oil powders and from their respective redispersed oil powders was differently affected by pH and polymer type. It was hypothesized that the release had been influenced by the electrostatic interactions between salicylic acid and emulsifiers, whereas the transdermal performance could have been determined by the particle or aggregate sizes of the formulations.KEY WORDS: carrageenan, chitosan, oil powders, release, salicylic acid, topical delivery, whey proteins     

Stability of the oil-in-water type triacylglycerol emulsions

Lipid emulsions with saturated triacylglycerols (TAGs) with 4 to 10 carbons in each acyl chain were prepared to study how the oil component alters the stability of the lipid emulsions when phosphatidylcholines were used as emulsifiers. The average droplet size of the emulsions became smaller as the chain length of the TAG increased. For a given oil, emulsion with smaller droplets was formed with an emulsifier having higher HLB value. The influence of HLB values on the droplet size was biggest for the tributyrin (C4) emulsions. For the tricaprylin (C8) emulsions, droplet size was identical at given emulsifier concentrations regardless of HLB values. The HLB value and the concentration of the emulsifiers also affect the droplet size of the emulsions. The emulsions with smaller average droplet size were more stable than with bigger size for 20 days. The oil and water (o/w) interfacial tension is inversely proportional to the initial droplet size of the emulsion.     

Development of Lapachol Topical Formulation: Anti-inflammatory Study of a Selected Formulation

This study aimed at developing a topical formulation of lapachol, a compound isolated from various Bignoniaceae species and at evaluating its topical anti-inflammatory activity. The influence of the pharmaceutical form and different types of emulsifiers was evaluated by in-vitro release studies. The formulations showing the highest release rate were selected and assessed trough skin permeation and retention experiments. It was observed that the gel formulation provided significantly higher permeation and retained amount (3.9-fold) of lapachol as compared to the gel-cream formulation. Antinociceptive and antiedematogenic activities of the most promising formulation were also evaluated. Lapachol gel reduced the increase in hind-paw volume induced by carrageenan injection and reduced nociception produced by acetic acid (0.8% in water, i.p.) when used topically. These results suggest that topical delivery of lapachol from gel formulations may be an effective medication for both dermal and subdermal injuries.     

The Influence of Emulsion Droplet Interactions on the Structural,Material and Functional Properties of a Model Mozzarella Cheese

We present findings on the influence of interfacial layer composition on the colloidal interactions and associated structural and material properties of oil-in-protein gel emulsions, as applied to a model Mozzarella cheese analogue. Model cheese samples were produced through thermal mixing of pre-prepared oil-in-water emulsions with a renneted casein gel. Sodium caseinate and Tween 20 were used as the emulsifiers. Microstructural analysis showed sodium caseinate stabilised droplets to be homogeneously dispersed within the cheese structure, whilst droplets stabilised by Tween 20 were phase concentrated into localised fat domains within the continuous protein network. Particle size measurements determined that, on chilled storage, the droplets in these localised regions underwent extensive partial coalescence, whilst the homogenously distributed caseinate droplets showed little change in droplet size. Small deformation rheology (4 to 80 °C) determined the sodium caseinate emulsion as providing a reinforcing effect on the protein network across the entire temperature range, while the Tween 20 emulsion was observed to mechanically strengthen the cheese structure at only at temperatures for which the fat phase was solid whilst serving to weaken the structure on transitioning to a molten state. Differences in droplet structure and stability were determined as influencing cheese melt and flow characteristics. During melting, no oiling-off observed for cheese samples comprising sodium caseinate stabilised droplets, compared to Tween 20 stabilised emulsions where extensive oiling-off was observed. Findings corroborate the hypothesis that caseinate coated droplets behave as active fillers within the protein network, whilst the Tween 20 stabilised emulsion are non-interactive.     

Stability of emulsions stabilised by two physiological surfactants: L-alpha-phosphatidylcholine and sodium taurocholate

The emulsion phase formed within the stomach and duodenum during digestion of a fatty meal has been modelled using two physiological surfactants, the phospholipid L-alpha-phosphatidylcholine (PC) and the bile salt sodium taurocholate (NaT). Upon dilution of the phospholipid stabilised emulsions with a solution of NaT the bile salt became incorporated into the oil/water interface imparting a negative charge to the droplet surface. The magnitude of the droplet microelectrophoretic mobility for the mixed PC and NaT system was 47% of that found for emulsion droplets stabilised by NaT alone. But the electrostatic repulsion between droplets was not sufficient to account for the observed improvement in emulsion stability to coalescence. It is suggested that a residual liquid crystalline phospholipid interface is present imparting a significant steric component to the stabilisation of the emulsions droplets.     

In Situ Enzymatic Synthesis of Polar Lipid Emulsifiers in the Preparation and Stabilisation of Aerated Food Emulsions

We report on the direct incorporation of a lipase derived from Rhizomucor miehei, into aeratable food emulsion formulations, with the objective of enzymatically generating polar lipid fractions during processing, and which are able to demonstrate equivalent functionality to chemically synthesised monoglycerides. Findings showed that the lipolysis of palm oil-in-water emulsions produced a combination of predominantly oleic monoglyceride and palmitic fatty acid fractions. The extent of hydrolysis was able to be controlled through concentration of enzyme, reaction time, and reaction temperature. Hydrolysis was terminated via inactivation of the enzyme through high heat treatment of emulsions. Emulsion properties, notably stability under shear, were seen to be highly dependent on the extent of lipolysis. When applied to model whipping and ice cream formulations, lipolytic generation of polar lipids was shown to promote both partial coalescence and fat globule adsorption to bubble surfaces, generating structures equivalent to those produced by use of commercial emulsifiers. Product properties, such as physical stability and material properties showed variation according to the extent of lipolysis. Our results demonstrated that enzymatic lipolysis of emulsions under controlled conditions could be optimised to deliver requisite droplet functionality for the structuring and stabilisation of aerated food emulsions. Findings are of significance, not only when considering the potential for replacement of chemically derived emulsifiers in such formulations, but also from the perspective that this approach can readily be incorporated into existing manufacturing process operations.     

Factors Affecting Foamed Emulsions Prepared with an Extract from <Emphasis Type="Italic">Quillaja saponaria</Emphasis> Molina: Oil Droplet Size,pH and Presence of Beta-Lactoglobulin

Oil is well-known to act as antifoam and to destabilize foam lamellae by bridging between two adjacent foam bubbles. It was hypothesized that an optimal oil droplet size exists with respect to the stability of a foamed emulsions, where the oil droplets are sufficiently small to postpone bridging and the amount of free surfactant is sufficient to stabilize the oil/water-interface and the air/water-interface. Emulsions with 0.3% Quillaja saponin and a median oil drop-let size between 0.2 and 2.0 μm were prepared under varying homogenization conditions and characterized in a dynamic foam analyzer. Results confirmed the above mentioned hypothesis. Stability of the foamed emulsions considerably increased with increasing pH, which was attributed to electrostatic repulsion between oil droplets and the effect on the balance between disjoining pressure and capillary pressure. In a binary system containing proteins and saponins, stability of foamed emulsions can be further increased when emulsifiers are added sequentially. When the emulsion is stabilized by β-LG and QS is added after emulsification stability of the foamed emulsion is distinctly higher compared to systems, where QS and β-LG are added prior to emulsification. Future studies should deepen our understanding of these complex dispersed systems by investigating the molecular interactions including other proteins and additional food constituents.     

Microemulsion for topical delivery of fenoprofen calcium: in vitro and in vivo evaluation

The aim of this study was to investigate microemulsion (ME) based topical delivery system for fenoprofen calcium (FPCa) to eliminate its oral gastrointestinal adverse effects. ME was prepared by the water titration method using oleic acid as oil phase, tween 80 as a surfactant and propylene glycol as a cosurfactant. Oleic acid was selected as oil phase due to its good solubilizing capacity. ME existence region was determined using pseudo-ternary phase diagrams for preparing different formulations. Six different formulations were selected with various values of oil (25–68%), water (2–3%), and the mixture of surfactant and cosurfactant (1:1) (24–67%). The selected ME formulae were characterized for optical birefringence, transmission electron microscopy (TEM), pH, % transmittance, electronic conductivity, drug content, droplet size, rheological properties and stability evaluation. In vitro release study of FPCa from ME s through the synthetic membrane and hairless rat skin were evaluated. The optimized formula ME5 consisting of 5% w/w FPCa, 60% w/w oleic acid as oil phase, 3% w/w aqueous phase, and 32% w/w of surfactant phase containing Tween 80 and propylene glycol (1:?1) showed the highest transdermal flux and highest skin permeation rate. Finally, the % inhibition of carrageenan-induced rat paw edema of the optimized formula ME5 was highly significant (p?0.001) as compared to plain gel of FPCa. In conclusion, ME is a promising technique for topical delivery of FPCa.     

Legume Protein Isolates for Stable Acidic Emulsions Prepared by Premix Membrane Emulsification

Proteins originating from dry legumes are not that much used in food formulations, yet, they are interesting components from a sustainability point of view, and could have interesting functional properties, e.g. for emulsion preparation. Therefore, this work focuses on the potential of the water soluble part of pea, chickpea and lentil protein isolates under acidic emulsions (pH 3.0) using a novel mild technique: premix membrane emulsification. Pea proteins (PP) and chickpea proteins (CP) lower the interfacial tension in the same way as whey protein isolate (WPI), which suggests that they could facilitate emulsion droplet formation similarly as WPI, while lentil proteins (LP) are slightly less effective. It is possible to make oil-in-water (O/W) emulsions with an average droplet diameter (d _4,3 ) of ~5 μm after 5 cycles in the premix system. The droplet size distribution of the emulsions remained constant during one day of storage, indicating that legume proteins are able to form and kinetically stabilize O/W emulsions. CP and PP exhibited emulsifying properties comparable to those of WPI, whereas LP is slightly less efficient, therewith indicating the great potential and that pea and chickpea protein isolates hold as emulsifiers in acidic food formulations.     

Temporal Aroma Release Profile of Solid and Liquid Droplet Emulsions

The release kinetics of four model aroma compounds from coarse (d ₃₂ = 1.0 μm) and fine (d ₃₂ = 0.25 μm) eicosane and hydrogenated palm stearin (HPS) emulsions prepared with either solid or liquid lipid droplets were measured using a model mouth instrument. For both lipids, the release of aroma compounds from emulsions with solid droplets was higher than from emulsions with liquid droplets. This difference was greater for less polar aroma compounds. The release from solid eicosane droplets increased with particle size but no such effect was observed for HPS emulsions, however, the release from solid eicosane was higher than solid HPS. The initial aroma release profile of the solid droplet emulsion matches that of a similar liquid oil emulsion but requires much less added aroma. Meeting presentation: Presented at 98th AOCS Annual Meeting and Expo in Quebec City, Canada.     

Development of Microsponges for Topical Delivery of Mupirocin

The goal of the present study was to develop and evaluate microsponge-based topical delivery system of mupirocin for sustained release and enhanced drug deposition in the skin. Microsponges containing mupirocin were prepared by an emulsion solvent diffusion method. The effect of formulation and process variables such as internal phase volume and stirring speed on the physical characteristics of microsponges were examined on optimized drug/polymer ratio by 3² factorial design. The optimized microsponges were incorporated into an emulgel base. In vitro drug release, ex vivo drug deposition, and in vivo antibacterial activity of mupirocin-loaded formulations were studied. Developed microsponges were spherical and porous, and there was no interaction between drug and polymer molecules. Emulgels containing microsponges showed desired physical properties. Drug release through cellulose dialysis membrane showed diffusion-controlled release pattern and drug deposition studies using rat abdominal skin exhibited significant retention of active in skin from microsponge-based formulations by 24 h. The optimized formulations were stable and nonirritant to skin as demonstrated by Draize patch test. Microsponges-based emulgel formulations showed prolonged efficacy in mouse surgical wound model infected with S. aureus. Mupirocin was stable in topical emulgel formulations and showed enhanced retention in the skin indicating better potential of the delivery system for treatment of primary and secondary skin infections, such as impetigo, eczema, and atopic dermatitis.     

Encapsulation of Lipophilic Bioactive Molecules by Microchannel Emulsification

Currently, much effort is being invested in novel formulations of bioactive molecules, such as emulsions, for pharmaceutical, food, and cosmetic applications. Therefore, methods to produce emulsions with controlled-size droplets of uniform size distribution have been developed. On this concern, a microfluidic device called the microchannel (MC) was used in this work for emulsification. This is a novel method for producing monodispersed emulsion droplets with very narrow droplet size distribution and low energy input, due to the spontaneous droplet generation basically driven by the interfacial tension, unlike other conventional emulsification processes. This technology provides the formulation of oil-in-water (O/W) emulsions containing lipophilic active molecules with increased bioavailability, which may be readily absorbed by the human body. MC emulsification enables the preparation of highly monodispersed O/W emulsions, which may be applied as enhancer on active molecules delivery systems, as well as in foodstuff. In this study, formulations of O/W emulsions loaded with bioactive molecules, such as β-carotene and γ-oryzanol, were prepared by the MC emulsification process. Refined soybean oil containing the dissolved lipophilic molecule and either sugar ester or gelatin solution (1 wt.%) were used as the dispersed and continuous phases, respectively. The emulsification process conducted using the asymmetric straight-through MC plate enabled the production of monodispersed O/W emulsions, resulting in β-carotene-loaded O/W emulsions with average droplet size (d _av) of 27.6 μm and coefficient of variation (CV) of 2.3% and γ-oryzanol-loaded droplets with d _av of 28.8 μm and CV of 3.8%. The highly monodisperse β-carotene-loaded droplets were physically stable throughout the storage period observed, resulting in droplets with d _av 28.2 μm and CV of 2.9% after 4 months storage in darkness at 5 °C. Single micrometer-sized monodisperse emulsions loaded with β-carotene were successfully formulated using the grooved MC emulsification, resulting in droplets with d _av of 9.1 μm and CV of 6.2%. This work was funded by The Ministry of Agriculture, Forestry and Fisheries of Japan, through the Food Nanotechnology Project, and the Japan Society for the Promotion of Science.     

Influence of Interfacial Composition on in Vitro Digestibility of Emulsified Lipids: Potential Mechanism for Chitosan's Ability to Inhibit Fat Digestion

The objective of this study was to investigate the influence of interfacial composition and electrical charge on the in vitro digestion of emulsified fats by pancreatic lipase. An electrostatic layer-by-layer deposition technique was used to prepare corn oil-in-water emulsions (3 wt% oil) that contained droplets coated by (1) lecithin, (2) lecithin–chitosan, or (3) lecithin–chitosan–pectin. Pancreatic lipase (1.6 mg mL⁻¹) and/or bile extract (5.0 mg mL⁻¹) were added to each emulsion, and the particle charge, droplet aggregation, and free fatty acids released were measured. In the presence of bile extract, the amount of fatty acids released per unit amount of emulsion was much lower in the emulsions containing droplets coated by lecithin–chitosan (38 ± 16 μmol mL⁻¹) than those containing droplets coated by lecithin (250 ± 70 μmol mL⁻¹) or lecithin–chitosan–pectin (274 ± 80 μmol mL⁻¹). In addition, there was much more extensive droplet aggregation in the lecithin–chitosan emulsion than in the other two emulsions. We postulated that lipase activity was reduced in the lecithin–chitosan emulsion as a result of the formation of a relatively thick cationic layer around each droplet, as well as the formation of large flocs, which restricted the access of the pancreatic lipase to the lipids within the droplets. Our results also suggest that droplets initially coated by a lecithin–chitosan–pectin layer did not inhibit lipase activity, which may have been because the chitosan–pectin desorbed from the droplet surfaces thereby allowing the enzyme to reach the lipids; however, further work is needed to establish this. This information could be used to create food emulsions with low caloric level, or to optimize diets for individuals with lipid digestion problems.     

Emulsifier Dependent <Emphasis Type="Italic">in vitro</Emphasis> Digestion and Bioaccessibility of β-Carotene Loaded in Oil-in-Water Emulsions

This study was performed to examine the effect of emulsifiers used to coat emulsion droplets containing β-carotene on the behavior of lipid digestion and bioaccessibility. Different emulsifiers (whey protein isolate, soy protein isolate, sodium caseinate, Tween 20, and soy lecithin) were used to prepare emulsions with similar sized droplets (200–400 nm). Protein-stabilized emulsions showed a similar behavior of digestion, and morphological change in the simulated gastrointestinal conditions. Soy lecithin-stabilized emulsions showed the lowest rate and extent of lipid digestion probably due to the low emulsifying capability of soy lecithin, showing coalesced droplets occurring after exposure to the gastric phase. Tween 20-stabilized emulsions had a lower rate and extent of lipid digestion than that of protein-stabilized emulsions, even though Tween 20-stabilized emulsions had a more stable structure to resistant to aggregation in gastric phase. Even though the difference in the digestion rate and extent, β-carotene bioaccessibility was not significantly different among emulsions stabilized by different emulsifiers at p?<?0.05.     

Transdermal Delivery of an Anti-Cancer Drug via W/O Emulsions Based on Alkyl Polyglycosides and Lecithin: Design,Characterization, and <Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of the Possible Irritation Potential in Rats

The purpose of this work was to develop w/o emulsions that could be safely used to promote transdermal delivery of 5-fluorouracil (5-FU). Two pseudo-ternary phase diagrams comprising oleoyl-macrogol glycerides, water, and a surfactant/co-surfactant (S/CoS) mixture of lecithin, ethanol, and either coco glucoside or decyl glucoside were investigated for their potential to develop promising 5-FU emulsions. Six systems were selected and subjected to thermodynamic stability tests; heat–cool cycles, centrifugation, and finally freeze–thaw cycles. All systems passed the challenges and were characterized for transmission electron microscopy, droplet size, rheological behavior, pH, and transdermal permeation through newly born mice skin in Franz diffusion cells. The systems had spherical droplets ranging in diameter from 1.81 to 2.97 μm, pH values ranging from 7.50 to 8.49 and possessed Newtonian flow. A significant (P < 0.05) increase in 5-FU permeability parameters as steady-state flux, permeability coefficient was achieved with formula B5 comprising water (5% w/w), S/CoS mixture of lecithin/ethanol/decyl glucoside (14.67:12.15:18.18% w/w, respectively) and oleoyl-macrogol glycerides (50% w/w). When applied to shaved rat skin, this system was well tolerated with only moderate skin irritation that was recovered within 12 h. Indeed, minor histopathologic changes were observed after 5-day treatment. Further studies should be carried out, in the future, to investigate the potentiality of this promising system to promote transdermal delivery of 5-FU through human skin.     

Effect of Gum Arabic,Gum Ghatti and Sugar Beet Pectin as Interfacial Layer on Lipid Digestibility in Oil-in-Water Emulsions

The impact of gum arabic (GA), ghatti gum (GG), and sugar beet pectin (SBP) on the digestion rate of emulsified lipids is investigated in vitro under model duodenal digestion condition. The aim was to understand the role of the interfacial layer surrounding the lipid droplets on lipid hydrolysis in order to control lipid digestion. The emulsifier concentration required to provide the same emulsion droplet size decreased in the order: GA > GG > SBP, demonstrating the best emulsifying activity of SBP. The rate and extent of free fatty acid release during lipid digestion did not differ significantly among the three types of gums in emulsions with D[2,3] < 2 μm. However, considerable difference was observed in emulsions with D[2,3] > 2 μm, and the digestive rate decreased in the order: GA > SBP > GG. The difference in digestion rate was attributed to the stability of the emulsified lipid droplets in the stimulated intestinal juice and the resistance of interfacial layer against displacement by bile salts. The difference of resisting against displacement by bile salts for the interfacial layers was detected with bile salts concentration of 0.025 mg/mL, and all of the pre-adsorbed emulsifiers could be completely displaced from interface by bile salts at 5 mg/mL. Emulsions with SBP were susceptible to Ca²⁺ and Na⁺ in simulated intestinal juice, resulting in the flocculation and coalescence of emulsion droplets. A reduction of the surface area of lipids would contribute to a slow digestion. Emulsion stabilized by GG was very effective at retarding lipolysis mainly due to the affinity of linked protein moieties of GG and its hydrophobic binding with bile salts. The knowledge gained in the study has important implications in designing proper emulsion-based systems for controlling lipid digestibility at specific sites within the gastrointestinal tract.     

Formulation of Microemulsion Systems for Dermal Delivery of Silymarin

Silymarin is a standardized extract from Silybum marianum seeds, known for its many skin benefits such as antioxidant, anti-inflammatory, and immunomodulatory properties. In this study, the potential of several microemulsion formulations for dermal delivery of silymarin was evaluated. The pseudo-ternary phase diagrams were constructed for the various microemulsion formulations which were prepared using glyceryl monooleate, oleic acid, ethyl oleate, or isopropyl myristate as the oily phase; a mixture of Tween 20®, Labrasol®, or Span 20® with HCO-40® (1:1 ratio) as surfactants; and Transcutol® as a cosurfactant. Oil-in-water microemulsions were selected to incorporate 2% w/w silymarin. After six heating–cooling cycles, physical appearances of all microemulsions were unchanged and no drug precipitation occurred. Chemical stability studies showed that microemulsion containing Labrasol® and isopropyl myristate stored at 40°C for 6 months showed the highest silybin remaining among others. The silybin remainings depended on the type of surfactant and were sequenced in the order of: Labrasol® > Tween 20® > Span 20®. In vitro release studies showed prolonged release for microemulsions when compared to silymarin solution. All release profiles showed the best fits with Higuchi kinetics. Non-occlusive in vitro skin permeation studies showed absence of transdermal delivery of silybin. The percentages of silybin in skin extracts were not significantly different among the different formulations (p > 0.05). Nevertheless, some silybin was detected in the receiver fluid when performing occlusive experiments. Microemulsions containing Labrasol® also were found to enhance silymarin solubility. Other drug delivery systems with occlusive effect could be further developed for dermal delivery of silymarin.Key words: dermal delivery, microemulsion, silybin, silymarin     

Evaluation of Electrostatic Interaction between Lysolecithin and Chitosan in Two-Layer Tuna Oil Emulsions by Nuclear Magnetic Resonance (NMR) Spectroscopy

The main objective of this work was to investigate the electrostatic interaction between lysolecithin and chitosan in two-layer tuna oil-in-water emulsions using nuclear magnetic resonance (NMR) spectroscopy. The influence of chitosan concentration on the stability and properties of these emulsions was also evaluated. The 5 wt% tuna oil one-layer emulsion (lysolecithin-stabilized oil droplets without chitosan) and two-layer emulsions (lysolecithin-chitosan stabilized oil droplets) containing 5 wt% tuna oil, 1 wt% lysolecithin and various chitosan concentrations (0.025–0.40 wt%) were prepared. The one-dimensional (1D) ³¹P and ¹H NMR spectra of emulsions were then recorded at 25 °C. The results showed that addition of chitosan affected the stability and properties of lysolecithin-stabilized one-layer emulsions. The ³¹P NMR peak of the choline head group on lysolecithin molecules disappeared when chitosan was added at concentrations above neutralization concentration (> 0.05 wt%). The ¹H NMR peak intensity monitoring free amino groups (?NH ₃ ⁺) of chitosan showed a strong positive linear relationship to the chitosan concentration with a high correlation coefficient (R² ≈ 0.99). This ¹H NMR peak in emulsions could not be detected for chitosan in emulsions lower than saturation concentration (< 0.15 wt%). These phenomena indicate an electrostatic interaction between lysolecithin and chitosan at droplet surface in emulsion and were consistent with the results from zeta-potential measurements. The T ₂* relaxation time of the choline head group (N-(CH ₃)₃) signal of lysolecithin also confirmed that lysolecithin-chitosan electrostatic interaction occurs at the surface of oil droplets in two-layer emulsions. The results suggest that NMR spectroscopy can be used as an alternative method for monitoring the electrostatic interaction between surfactant and oppositely charged electrolytes or biopolymers in two-layer emulsions.     

Changes in Colloidal Properties of Oil in Water Emulsions Stabilized with Sodium Caseinate Observed by Acoustic and Electroacoustic Spectroscopy

Sodium caseinate is a commonly used emulsifier in foods, as it adsorbs on the surface of oil droplets and stabilizes them via electrostatic and steric stabilization, forming a polyelectrolyte layer at the interface. Since the protein interface is affected by varying environmental conditions such as pH, ionic strength, concentration of unadsorbed polymers, these emulsions are prone to a variety of destabilization mechanisms. The objective of the present work was to observe the destabilization of sodium caseinate stabilized oil in water emulsions using electroacoustic spectroscopy. This technique can be utilized for the characterization of concentrated colloidal systems in situ, without dilution. The electroacoustic and ultrasonic properties of soy oil in water emulsions were determined for sodium caseinate stabilized emulsions under conditions known to cause destabilization. Ultrasonic attenuation and electrophoretic mobility (ζ-potential) could clearly follow the changes occurring in the emulsion droplets, under minimal sample disruption. This is critical for these systems in a very fragile, metastable state. The emulsions were stable to the addition of high methoxyl pectin (HMP) up to 0.1% HMP. Addition of free sodium caseinate induced depletion flocculation, causing a decrease in the attenuation and electrophoretic mobility measured. The presence of HMP limited depletion interactions. Acidification of the emulsion droplets resulted in a clear sol–gel transition, as shown by a steep increase in the particle size and a decrease in attenuation. Again, destabilization was limited by HMP addition. It was concluded that ultrasonics and electroacoustics are suitable techniques to understand the details of the destabilization processes occurring to food emulsions, measured in situ.     

Topical Cream-Based Dosage Forms of the Macrocyclic Drug Delivery Vehicle Cucurbit[6]uril

The macrocycle family of molecules called cucurbit[n]urils are potential drug delivery vehicles as they are able to form host-guest complexes with many different classes of drugs. This study aimed to examine the utility of Cucurbit[6]uril (CB[6]) in topical cream-based formulations for either localised treatment or for transdermal delivery. Cucurbit[6]uril was formulated into both buffered cream aqueous- and oily cream-based dosage forms. The solid state interaction of CB[6] with other excipients was studied by differential scanning calorimetry and the macrocycle''s transdermal permeability was determined using rat skin. Significant solid state interactions were observed between CB[6] and the other dosage form excipients. At concentrations up to 32% w/w the buffered aqueous cream maintained its normal consistency and could be effectively applied to skin, but the oily cream was too stiff and is not suitable as a dosage form. Cucurbit[6]uril does not permeate through skin; as such, the results imply that cucurbituril-based topical creams may potentially only have applications for localised skin treatment and not for transdermal drug delivery.