Whey Protein/Polysaccharide-Stabilized Emulsions: Effect of Polymer Type and pH on Release and Topical Delivery of Salicylic Acid

Abstract

Abstract. Emulsions are widely used as topical formulations in the pharmaceutical and cosmetic industries. They are thermodynamically unstable and require emulsifiers for stabilization. Studies have indicated that emulsifiers could affect topical delivery of actives, and this study was therefore designed to investigate the effects of different polymers, applied as emulsifiers, as well as the effects of pH on the release and topical delivery of the active. O/w emulsions were prepared by the layer-by-layer technique, with whey protein forming the first layer around the oil droplets, while either chitosan or carrageenan was subsequently adsorbed to the protein at the interface. Additionally, the emulsions were prepared at three different pH values to introduce different charges to the polymers. The active ingredient, salicylic acid, was incorporated into the oil phase of the emulsions. Physical characterization of the resulting formulations, i.e., droplet size, zeta potential, stability, and turbidity in the water phase, was performed. Release studies were conducted, after which skin absorption studies were performed on the five most stable emulsions, by using Franz type diffusion cells and utilizing human, abdominal skin membranes. It was found that an increase in emulsion droplet charge could negatively affect the release of salicylic acid from these formulations. Contrary, positively charged emulsion droplets were found to enhance dermal and transdermal delivery of salicylic acid from emulsions. It was hypothesized that electrostatic complex formation between the emulsifier and salicylic acid could affect its release, whereas electrostatic interaction between the emulsion droplets and skin could influence dermal/transdermal delivery of the active.

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

“…The transdermal delivery results of salicylic acid from the redispersed oil powders were also similar to that obtained by Combrinck et al (14). With regards to the effect of pH, the degree of ionization of salicylic acid could have affected the transdermal delivery thereof, with a decrease in permeation with increasing ionization of salicylic acid, according to the pH partition hypothesis.…”

“…The release data obtained for the template emulsions and redispersed powders were similar to that obtained by Combrinck et al (14). It was therefore concluded that electrostatical interactions between the salicylic acid and the emulsifiers of the emulsion droplets had affected the release of salicylic acid from these formulations.…”

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

“…[31] Other similar nonionic surfactants were also employed: Tween 20, 40, 60, and 80 (polyoxyethylene sorbitan monolaurate), [66][67][68] Span 20, 40, 60, and 80 (sorbitan monolaurate) [69,70] and Kolliphor HS-15 (polyoxyethylene-660-hydroxystearate) (see examples in Figure 1B). [71] In addition, common surfactants of different chemical nature can be also used for NEs preparation: poloxamers (also known as Pluronics), [72] amphiphilic proteins like casein, [73,74] lactoglobulin, [75] polysaccharides (e.g., gums, starch derivatives), [76] and PEG containing block copolymers. [77] Ionic surfactants have also been used for preparation of NEs, like for instance, sodium dodecyl sulfate and docusate sodium salt (AOT).…”

Glycation of soy protein isolate with two ketoses: d‐Allulose and fructose

“…Protein concentration, pH, temperature and ionic strength had an effect on the emulsification activity of the proteins (Combrinck et al ., 2014). In addition, glycation of proteins is also known to affect their emulsification activity, and in this study, emulsification properties are also determined (Table 5).…”