Formulation of Pickering emulsions for the development of surfactant‐free sunscreen creams

Abstract

Objective Pickering emulsions are increasingly used in the pharmaceutical and cosmetic fields, especially for topical applications, since these systems require solid particles as emulsifiers instead of surfactants which are known to cause skin irritation. The solid inorganic nanoparticles (TiO2 and ZnO) used as UV filters in sunscreen formulations may also stabilize emulsion droplets, so that the utility of surfactants may be questioned. Surfactant‐free sunscreen emulsions solely stabilized by such nanoparticles (NPs) have been studied. Methods The ability of these NPs to stabilize o/w emulsions containing a ‘model’ oil phase, the C12‐C15 alkylbenzoate, has been assessed. ZnO and hydrophilic silica‐coated TiO2 NPs widely used in sunscreen products were used together with their mixtures. The emulsification efficiency, the control of droplet size and the stability of o/w Pickering emulsions solely stabilized by NPs were investigated. A ZnO/TiO2 NPs mixture characterized by a theoretical SPF of 45 was finally used as unique emulsifiers to develop a surfactant‐free sunscreen emulsion. Results Stable Pickering emulsions containing 10 up to 60 wt% of C12‐C15 alkyl benzoate were formulated with 2 wt% ZnO in the aqueous phase. The droplet size was controlled by the solid NPs content with respect to oil and the emulsification process. Hydrophilic TiO2 NPs did not allow the stabilization of emulsions. The substitution of TiO2 for ZnO up to 60–70 wt% in a 20/80 o/w emulsion was successfully performed. Finally, a ZnO/TiO2 NP mixture was tested as unique emulsifier system for the formulation of a sunscreen cream. Despite a lower viscosity, the obtained Pickering emulsion was stable and exhibited a photoprotective effect similar to the corresponding surfactant‐based sunscreen cream with an in vitro SPF of about 45. Conclusion Surfactant‐free Pickering emulsions can be stabilized by the UV‐filter nanoparticles for the manufacture of sunscreen products.

Pickering emulsions stabilized with chitosan/collagen peptides nanoparticles as green topical delivery vehicles for cannabidiol (CBD)

“…The use of Pickering emulsions in dermal applications is finding increasing interest due to the consumers' demands and industry regulations to switch to green and safe formulations and to overcome the skin sensitization and irritation effects provoked by surfactants [14,[20][21][22]. Pickering emulsions stabilized with particles of biological origin have not been frequently reported for cosmetic applications.…”

The photocatalytic process in the treatment of polluted water

“…It is also corrosion resistant, low-cost, long-term, and environmentally friendly. (Goodeve 1937;Fujishima and Honda 1972;Awati et al 2003;Othman et al 2014) and organic pollutant photodegradation TiO 2 has been widely used in solar cells and solar harvesting (Lan et al 2013;Wold 1993;Bordes et al 2021;Hoffmann et al 1995) and is seen as a potential candidate (Chong et al 2010a;Goodeve 1937;Othman et al 2014;Roy et al 2011). Titanium dioxide (TiO 2 ) is often accessible in two forms: rutile and anatase, as seen in Fig.…”

Research of the market and economic state of enterprises in the cosmetics industry in the context of reforming the regulatory framework and harmonization in accordance with the requirements of the EU regulations

“…Scientists in different countries of the world are working on this issue. Specialists are engaged in improving the technology, introducing new formulation components, bioactive substances from natural raw materials of plant and animal origin [9][10][11], which improve the effectiveness of cosmetics and penetration of skin epidermis everywhere. However, in many cases, manufacturers introduce new components without proper legislative argumentation at the state level [12,13].…”