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Percorrer por autor "Morais, Maria Clara de"

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  • Development of microparticles incorporating chondroitin sulphate for application as Pickering stabilisers for topical applications
    Publication . Morais, Maria Clara de; Barreiro, M.F.; Santamaria-Echart, Arantzazu; Düsman, Elisângela
    Pickering emulsions, stabilised by solid particles, have been gaining prominence as an alternative to traditional surfactants and stabilisers, giving products of greater stability and unique characteristics. In this study, chitosan-based particles incorporating chondroitin sulphate were developed to produce Pickering emulsions for topical applications, followed by characterising the stabilising particles and the emulsions. For particle dispersion, size and distribution (DLS (dynamic light scattering)), stability (zeta potential (ζ)), and wettability (contact angle (θ)) were characterised. The emulsions’ type, droplet size and distribution (DLS), stability (zeta potential and creaming index (CI)), colour, rheological properties, antioxidant activity, toxicity, cytoprotection and skin corrosion were assessed. In preliminary tests, relatively large and uniform particles were obtained, identifying the most promising formulations and the most compatible oil. The particles showed good stability, demonstrated by zeta potential values above 30 mV (ζ = 32.30 ± 1.64 mV), indicating good electrostatic repulsion and colloidal stability. In addition, they exhibited relative hydrophobicity, evidenced by a contact angle greater than 90° (θ = 97.10 ± 2.91°), characterising a moderately hydrophobic surface. Two emulsions were prepared: a base emulsion and another with the addition of vitamin E. Both were identified as O/W (oil/water) emulsions, characterised by the aqueous phase being continuous. These emulsions remained stable for 30 days, without phase separation, showing controlled droplet growth and pseudoplastic behaviour in the rheological tests, properties of a gel-like material in the amplitude and frequency analysis. In addition, the vitamin E emulsion showed high antioxidant activity throughout the study period. The emulsions had a light green colour characteristic of olive oil, with no toxicity or cytoprotective properties.
    2024Dissertação de mestrado Acesso aberto Ver mais