Logo do repositório

Percorrer por autor "Oliveira, Bárbara Miqueletti de"

A mostrar 1 - 1 de 1
  • Multifunctional lignin-based pickering emulsions for cosmetic applications
    Publication . Oliveira, Bárbara Miqueletti de; Barreiro, M.F.; Santamaria-Echart, Arantzazu; Silva, Lucimara Lopes da
    Lignin is one of the most abundant polymers on Earth, and currently, around 95% of the extracted lignin is used to generate energy in industries. Lignin has remarkable properties that add high value as a raw material for developing new products. The main properties explored include antioxidant capacity, UV protection, and stabilization of oil-water interfaces, i.e., as Pickering emulsion stabilizers. These properties present the potential to formulate pharmaceutical and cosmetic products in high demand for environmentally eco-friendly products containing natural ingredients. Plant extracts mostly contain bioactive compounds, such as polyphenols and flavonoids (i.e., quercetin and ferulic acid), which can potentiate the bioactivity of lignin-based formulations. In this context, this work aimed to develop colloidal lignin-quercetin particles (CLQPs) to stabilize Pickering emulsions for cosmetic applications. For this, different conditions of the particle production process were studied, including the use of new lignin types, the solvent and antisolvent used, and the addition of purification steps. The optimized CLQPs consisted of using LIGNOVA Pure™ as the lignin type solubilized in 80% acetone aqueous solution (v/v) with a final concentration of 20%, pH 8 buffer as the antisolvent, and precipitation using the classic method. The optimum percentage of quercetin in the composition of the particles was 50% (w/w) relative to lignin (Q_50), which showed a median particle size of 462 ± 1 nm, an oil-water contact angle of 91.6 ± 0.1°, and a zeta potential of - 52.8 ± 2.7 mV. The optimized particles were used to stabilize Pickering emulsions (EQ_50), which showed the best oil-water ratio as 60/40, the smallest of the tested ratios, showing average droplet sizes of 26 ± 1 μm. The optimized emulsion was used to encapsulate ferulic acid (EQ_50F), which showed a yellowish-brown color, an emulsified layer of approximately 90%, an antioxidant activity (IC50) of 0.16 ± 0.35 mg/mL, a non-Newtonian shear-thinning fluid and gel-like behavior based on rheology tests, and a high stability during the 30 days period of storage. Therefore, the association of lignin and flavonoids is a promising strategy for formulating new bio-based cosmetics by combining the best properties of both components.
    2024Dissertação de mestrado Acesso restrito Ver mais