Whey protein/polysaccharide-stabilized emulsions: Effect of polymer type and pH on release and topical delivery of salicylic acid

Effect of pH on the soybean whey protein-gum arabic emulsion delivery systems for curcumin: Emulsifying, stability, and digestive properties

A novel curcumin (CUR) delivery system was developed using soybean whey protein (SWP)-based emulsions, enhanced by pH-adjustment and gum arabic (GA) modification. Modulating electrostatic interactions between SWP and GA at oil/water interface, pH provides favorable charging conditions for stable distribution between droplets. GA facilitated the SWP form a stable interfacial layer that significantly enhanced the emulsifying properties and CUR encapsulation efficiency of the system at pH 6.0, which were 90.15 ± 0.67%, 870.53 ± 3.22 m2/g and 2157.62 ± 115.31%, respectively. Duncan's test revealed significant improvements in thermal, UV, oxidative, and storage stabilities of CUR (P < 0.05). At pH 6.0, GA effectively protected CUR by inhibiting SWP degradation during gastric digestion and promoting the release of CUR by decreasing steric hindrance with oil droplets during intestinal digestion, achieving the highest CUR bioaccessibility (69.12% ± 0.28%) based on Duncan's test. The SWP-GA-CUR emulsion delivery system would be a novel carrier for nutrients.

Recent insights into Nanoemulsions: Their preparation, properties and applications

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

Safety Assessment of Bovine Milk Proteins and Protein Derivatives as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of 16 bovine milk proteins and protein-derived ingredients, which function mainly as skin and hair conditioning agents in personal care products. The Panel reviewed relevant data provided in this safety assessment, and concluded that these ingredients are safe in the present practices of use and concentration.

In Vitro Skin Delivery of Griseofulvin by Layer-by-Layer Nanocoated Emulsions Stabilized by Whey Protein and Polysaccharides

Griseofulvin is a poorly water-soluble drug administered orally to treat topical fungal infections of the skin and hair. However, oral administration leads to poor and unpredictable drug pharmacokinetics. Additionally, griseofulvin is unstable in the presence of light. A layer-by-layer (LbL) nanocoating approach was employed to curb these shortcomings by stabilizing emulsions, lyophilized emulsions, and reconstituted emulsions with a layer each of whey protein, and either hyaluronic acid, amylopectin, or alginic acid, which captured the drug. The coating materials are biological, environmentally benign, and plentiful. Photostability studies indicated that the LbL particles afforded 6 h of protection of the topical application. In vitro absorption studies showed that griseofulvin concentrated preferentially in the stratum corneum, with virtually no transdermal delivery. Therefore, LbL-nanocoated emulsions, lyophilized particles, and reconstituted lyophilized emulsions can produce a viable topical delivery system to treat superficial fungal infections.

Topical delivery of salicylates

Salicylates have a long history of use for pain relief. Salicylic acid and methyl salicylate are among the widely used topical salicylates namely for keratolytic and anti-inflammatory actions, respectively. The current review summarises both passive and active strategies, including emerging technologies employed to enhance skin permeation of these two salicylate compounds. The formulation design of topical salicylic acid targets the drug retention in and on the skin based on the different indications including keratolytic, antibacterial and photoprotective actions, while the investigations of topical delivery strategies for methyl salicylate are limited. The pharmacokinetics and metabolisms of both salicylate compounds are discussed. The current overview and future perspectives of the topical delivery strategies are also highlighted for translational considerations of formulation designs.

Dye-Loaded Nanoemulsions: Biomimetic Fluorescent Nanocarriers for Bioimaging and Nanomedicine

Lipid nanoemulsions (NEs), owing to their controllable size (20 to 500 nm), stability and biocompatibility, are now frequently used in various fields, such as food, cosmetics, pharmaceuticals, drug delivery, and even as nanoreactors for chemical synthesis. Moreover, being composed of components generally recognized as safe (GRAS), they can be considered as "green" nanoparticles that mimic closely lipoproteins and intracellular lipid droplets. Therefore, they attracted attention as carriers of drugs and fluorescent dyes for both bioimaging and studying the fate of nanoemulsions in cells and small animals. In this review, the composition of dye-loaded NEs, methods for their preparation, and emerging biological applications are described. The design of bright fluorescent NEs with high dye loading and minimal aggregation-caused quenching (ACQ) is focused on. Common issues including dye leakage and NEs stability are discussed, highlighting advanced techniques for their characterization, such as Förster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS). Attempts to functionalize NEs surface are also discussed. Thereafter, biological applications for bioimaging and single-particle tracking in cells and small animals as well as biomedical applications for photodynamic therapy are described. Finally, challenges and future perspectives of fluorescent NEs are discussed.

Chitosan reduces vitamin D bioaccessibility in food emulsions by binding to mixed micelles

Consumption of sufficiently high quantities of dietary fibers has been linked to a range of health benefits. Recent research, however, has shown that some dietary fibers interfere with lipid digestion, which may reduce the bioavailability of oil-soluble vitamins and nutraceuticals. For this reason, we examined the impact of a cationic polysaccharide (chitosan) on the bioaccessibility of vitamin D using the standardized INFOGEST in vitro digestion model. The vitamin D was encapsulated within an emulsion-based delivery system that contained whey protein-coated corn oil droplets. Our results showed that chitosan promoted severe droplet flocculation in the small intestine and reduced the amount of free fatty acids detected using a pH-stat method. However, a back-titration of the digested sample showed that the lipids were fully digested at all chitosan levels used (0.1-0.5%), suggesting that chitosan may have bound some of the free fatty acids released during lipid digestion. The presence of the chitosan decreased the bioaccessibility of vitamin D by about 37%, but this effect did not depend strongly on chitosan concentration (0.1-0.5%). It was hypothesized that chitosan bound to the vitamin-loaded mixed micelles and promoted their precipitation. The knowledge gained in this study might provide useful insights in designing emulsion-based delivery systems with high vitamin bioaccessibility.

Milk fat nanoemulsions stabilized by dairy proteins

Droplet size, polydispersity, physical and polymorphic stability of milk fat nanoemulsions produced by hot high-pressure homogenization and stabilized by whey protein isolate (WPI pH 4.0 or 7.0) or sodium caseinate (NaCas pH 7.0) were evaluated for 60 days of storage at 25 °C. Smaller droplets were observed for the NaCas pH 7.0 nanoemulsion, which also showed a lower polydispersity index, resulting in a stable emulsified system for 60 days. On the other hand, the nanoemulsion with bigger droplet size (WPI pH 4.0) showed reduced stability, probably due to the pH near the isoelectric point of the whey proteins. The nanostructured milk fat exhibited the same melting behavior as the bulk milk fat, with a balance between liquid and crystallized fat, and crystals in polymorphic form β'. This could be an advantage concerning the application of the system for delivery of bioactive compounds and improvement of the sensory properties of fat-based food. In summary, nanoemulsions stabilized by NaCas (pH 7.0) showed higher kinetic stability over the storage time, which from a technological application point of view is a very important factor in the food industry.

The Effect of Eugenol and Chitosan Concentration on the Encapsulation of Eugenol Using Whey Protein–Maltodextrin Conjugates

Eugenol has many functional properties for food and pharmaceutical purposes, especially as an antimicrobial agent. However, its use is constrained by its volatility and shelf life because it is easily degraded due to temperature, oxidation, and light. Research on encapsulation technology using biopolymers is still required to obtain the appropriate formulation in a eugenol delivery system. The aims of this research were to develop a new formulation of protein and polysaccharides in eugenol encapsulation and to determine the effect of eugenol and chitosan concentration on the characteristics of the emulsions and spray-dried powder produced. In this study, eugenol was encapsulated in whey protein–maltodextrin conjugates and chitosan through the double layer encapsulation method. The emulsions which were prepared with 2.0% eugenol were relatively more stable than those of 1.0% eugenol based on the polydispersity index and zeta potential values. Spray-dried powder which was prepared using an emulsion of 2.0% w/w eugenol and 0.33% w/w chitosan had the highest eugenol loading. The presence of chitosan resulted in more stable emulsions based on their zeta potential values, improved thermal stability of eugenol, increased eugenol loading to become twice as much as the loading obtained without chitosan, and modified release profile of eugenol from the spray-dried powders.

Nanoemulsions for "Nose-to-Brain" Drug Delivery

The blood–brain barrier (BBB) plays a fundamental role in protecting the brain from toxic substances and therefore also controls and restricts the entry of therapeutic agents. The nasal administration of drugs using the nose-to-brain pathway allows direct drug targeting into the brain, avoiding the first-pass effect and bypassing the BBB. Through the nasal route, the drug can access the brain directly along the trigeminal and olfactory nerves, which are located in the upper part of the nasal cavity. Nanoemulsions are formulations belonging to the field of nanomedicine. They consist of emulsions (commonly oil in water) stabilized by one or more surfactants—and eventually co-surfactants—delivered in droplets of small dimensions (sizes of 100–300 nm or less) with a high surface area. A mucoadhesive polymer such as chitosan can be added to the formulation to impair rapid nasal clearance. Nanoemulsions represent promising formulations to deliver drugs directly into the brain through the intranasal route. Therefore, they can be used as a possible alternative to oral administration, avoiding problems such as low solubility in water, poor bioavailability, enzymatic degradation and slow onset of action. This review focuses the present situation in literature regarding the use of nanoemulsions for nose-to-brain targeting, with particular attention to recent publications. Nasal nanoemulsions appear to be effective, non-invasive and safe drug delivery systems to achieve brain targeting for the treatment of neurological diseases.

Nanoemulsion: Concepts, development and applications in drug delivery

Nanoemulsions are biphasic dispersion of two immiscible liquids: either water in oil (W/O) or oil in water (O/W) droplets stabilized by an amphiphilic surfactant. These come across as ultrafine dispersions whose differential drug loading; viscoelastic as well as visual properties can cater to a wide range of functionalities including drug delivery. However there is still relatively narrow insight regarding development, manufacturing, fabrication and manipulation of nanoemulsions which primarily stems from the fact that conventional aspects of emulsion formation and stabilization only partially apply to nanoemulsions. This general deficiency sets up the premise for current review. We attempt to explore varying intricacies, excipients, manufacturing techniques and their underlying principles, production conditions, structural dynamics, prevalent destabilization mechanisms, and drug delivery applications of nanoemulsions to spike interest of those contemplating a foray in this field.

Methods to simulate rubbing of topical formulation for in vitro skin permeation studies

Rubbing a topical formulation on skin is generally assumed to enhance drug penetration. The aim of this study was to demonstrate different techniques such as using glass rod, rheometer, and gloved finger for rubbing a 2% salicylic acid gel on skin and investigate their effect on in vitro permeation of salicylic acid through dermatomed porcine ear skin. The studies included evaluation of the gel's rheological properties, gel distribution on skin surface, in vitro permeability, drug distribution in skin, skin extraction recovery, and mass balance. Rubbing with a gloved finger resulted in a uniform gel layer with a thickness of 49.61±15.33μm on the skin surface. No significant difference between the different test groups was observed in terms of the cumulative amount of drug that permeated in 24h (p>0.05). Drug levels in stratum corneum, epidermis, and dermis were also analyzed. Rubbing with gloved finger delivered significantly higher amount of drug into the skin layers as compared to other test groups (p<0.05). Amount of drug extracted from skin was reliably correlated to the actual drug levels in skin (R²=0.99). Considering drug amounts in different compartments, mass balance ranged from 75.86±2.90% to 80.44±2.99%.

Nanoparticle-Templated Formation and Growth Mechanism of Curved Protein Polymer Fibrils

We investigated the growth of biosynthetic protein polymers with templated curvature on pluronic nanospheres. The protein has a central silk-like block containing glutamic residues (S(E)) and collagen-like end-blocks (C). The S(E) blocks stack into filaments when their charge is removed (pH <5). Indeed, at low pH curved and circular fibers are formed at the surface of the nanospheres, which keep their shape after removal of the pluronics. The data reveal the mechanism of the templated fibril-growth: The growth of protein assemblies is nucleated in solution; small protein fibrils adsorb on the nanospheres, presumably due to hydrogen bond formation between the silk-like blocks and the pluronic PEO blocks. The surface of the pluronic particles templates further growth. At relatively low protein/pluronic weight ratios, only a fraction of the nanospheres bears protein fibers, pointing to a limiting amount of nuclei in solution. Because the nanospheres capture fibrils at an early stage of growth, they can be used to separate growth and nucleation rates in protein fibril formation. Moreover, the nanoparticle-templated growth of stable curved fibers opens ways to build proteinaceous nanocapsules from designed protein polymers.

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.