Browsing by Author "Lopes, Nayra Piscoso Saes"
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- Development of functional emulsions based on humic acids for cosmetic applicationPublication . Lopes, Nayra Piscoso Saes; Barreiro, Filomena; Santamaria-Echart , Arantzazu; Sipoli , Caroline Casagrande; Junior, Bogdan DemczukThe cosmetics market continues to grow, especially dermocosmetics, which combine aesthetic and therapeutic care. This growth is driving the development of more effective and sustainable formulations, such as Pickering emulsions, which utilize solid particles instead of synthetic surfactants. These latter are responsible for causing environmental impacts and adverse effects on the skin, including irritation and allergies. Humic acid, a natural active ingredient with antioxidant, anti-inflammatory, and photoprotective properties, is an innovative alternative for this type of system. In this context, this work aims to study Pickering emulsions stabilized with humic acid nanoparticles for the development of a dermocosmetic product. Different conditions for producing the particles were analyzed, including the solvent and anti-solvent used, concentration, and pH. The optimized nanoparticles were obtained by acid precipitation, using 0.5 M sodium hydroxide to solubilize the humic acid (final concentration of 10 g/L) and 0.5 M citric acid as the precipitating agent. The optimized particles were used to formulate Pickering emulsions, with an oil volume percentage of 65% showing the best results. The humic acid particles had an average particle size of 73.9 ± 9.7 nm and a three-phase contact angle (particles-water-sweet almond oil) of 65 ± 3.5º, revealing a hydrophilic character. The optimized emulsion consisted of round-shaped droplets with an average size of 44.2 ± 0.3 μm, resulting in an emulsified layer of over 95%, which indicated high stability after 30 days of storage. In addition, the emulsion exhibited a brown color, 14.8% inhibition of antioxidant activity, and, according to rheological analysis, a pseudoplastic, non-Newtonian fluid behavior with gel-like characteristics. It had a smooth texture to the touch, was easy to spread, and had low tackiness. These results demonstrate not only the feasibility of using humic acid particles as stabilizers in Pickering emulsions but also highlight their multifunctional potential for cosmetic applications. This is an unprecedented approach in the field of dermocosmetics, with scientific and technological relevance. Overall, this study presents an innovative, ecological, and effective alternative to the use of synthetic surfactants, offering new perspectives for the development of sustainable cosmetic products based on physical stabilization technologies utilizing nanoparticles.