BDTD - Biblioteca Digital de Teses e Dissertações
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Doctoral Thesis Desenvolvimento tecnológico de nanoemulsão de óleo de linhaça contendo avobenzona e tris-bifenil triazina: validação analítica, fotoestabilidade, fotoproteção in vitro e segurança cutânea ex vivo(Universidade Federal do Rio Grande do Norte, 2025-08-01) Miranda, Júlio Abreu; Egito, Eryvaldo Sócrates Tabosa do; http://lattes.cnpq.br/6907806915889763; https://orcid.org/0000-0003-0783-7447; http://lattes.cnpq.br/0126922350258900; Freitas, Rodrigo Pegado de Abreu; http://lattes.cnpq.br/3462462933163509; Verissimo, Lourena Mafra; https://orcid.org/0000-0002-9289-0455; http://lattes.cnpq.br/9173400981540256; Rosseto, Hélen Cássia; http://lattes.cnpq.br/7417144807480582; Soares, Daniel Cristian Ferreira; http://lattes.cnpq.br/0451950971908426Ultraviolet (UV) radiation is a major risk factor for various skin damages, including skin cancer, making sunscreens a key preventive strategy. In this context, the development of effective and safe sunscreen formulations remains a constant challenge in the cosmetic field. Therefore, this study aimed to develop, characterize, and evaluate in vitro a linseed oil-based nanoemulsion containing the UV filters avobenzone (AVO) and tris-bifenil triazine (TBPT), with a focus on improving AVO photostability, photoprotective efficacy, and skin safety. Initially, an HPLC method was developed and validated for the simultaneous quantification of AVO and TBPT, following the ICH guidelines and employing a Box-Behnken design. A nanoemulsion was then formulated, produced and optimized (NEUVMIXopt), containing 10% of linseed oil, 10% surfactant mixture (Kolliphor® RH 40:Span® 80 8,7:1,3), 1% AVO, 8% TBPT, 1% vitamin E, 0.2% potassium sorbate, 0.5% xanthan gum, and purified water to 100%. This formulation was characterized by transmission electron microscopy and dynamic light scattering, showing spherical morphology, clear distinction between TBPT particles and oil droplets, mean diameter of 147.48 ± 0.58 nm, polydispersity index of 0.23 ± 0.02, zeta potential of -25.09 ± 0.40 mV, and pH of 6.52 ± 0.10, indicating colloidal stability and suitability for topical application. Photostability assays demonstrated a significant increase in AVO half-life, from 39.24 minutes in linseed oil solution to 138.16 minutes in NEUVMIXopt. Furthermore, photoprotective efficacy studies using diffuse reflectance spectrophotometry showed that the developed formulation provided UV protection for all skin phototypes, with SPF values of 21.67 ± 6.67, a UVA/UVB ratio of 0.88 ± 0.01, and a critical wavelength of 381.67 ± 0.43 nm. Skin safety studies using porcine ear skin revealed that the formulation had no transdermal permeation potential, favoring local deposition of UV filters in the outer skin layers. Finally, histological analysis of the treated pig skin showed no morphological changes, indicating the absence of irritant potential. Altogether, these results reinforce the potential of combining nanotechnology with natural oils as a promising strategy for developing more effective and safer sunscreen products.Master Thesis Desenvolvimento de nanoemulsão fotoprotetora à base de óleo de linhaça (Linum usitatissimum L.) e de filtros ultravioleta avobenzona e tris-biphenyl triazine (nano)(Universidade Federal do Rio Grande do Norte, 2022-08-24) Miranda, Júlio Abreu; Egito, Eryvaldo Socrates Tabosa do; Machado, Lucas Amaral; https://orcid.org/0000-0002-8996-189X; http://lattes.cnpq.br/1374781426040441; http://lattes.cnpq.br/6907806915889763; https://orcid.org/0000-0003-0783-7447; http://lattes.cnpq.br/0126922350258900; Oliveira, Ana Katherine da Silveira Gonçalves de; https://orcid.org/0000-0002-8351-5119; http://lattes.cnpq.br/3436756337251449; Damasceno, Gabriel Azevedo de BritoSkin damage caused by solar radiation, such as skin cancer, is known to be reduced by the use of sunscreens. Current efforts on the development of photoprotective formulations are focused on the improvement of those on the market. Accordingly, natural products, e.g., linseed oil, have been used on the development of new sunscreens once they can increase formulations’ photoprotective effect and provide them with additional characteristics, as antioxidant potential. Among different formulations, nanoemulsions are promising systems for this application due to their kinetic stability and possibility of uniform distribution of ultraviolet filters on the skin. The aim of this study was to develop a photoprotective linseed oil-based nanoemulsion with avobenzone and tris-biphenyl triazine (nano) as ultraviolet filters, which in association provide a broad spectrum of ultraviolet protection. The developed nanoemulsion was obtained using 9.9 % of linseed oil, 10 % of surfactants, 0.1 % of avobenzone, 8 % of tris-biphenyl triazine (nano) and 72 % of water. The physicochemical characterization of the nanoemulsion revealed average droplet size of 132.5 ± 8.3 nm, polydispersity index of 0.23 ± 0.03, zeta potential of -23.99 ± 1.28 mv, pH value of 6.77 ± 0.08, electrical conductivity of 1001.33 ± 3.06 µS/cm and in vitro solar protection factor (SPF) of 21. Further, the total content of ultraviolet filters remained stable over time, suggesting a preliminary SPF stability. The results of this study showed that the linseed oil-based nanoemulsion was kinetically stable and that the oil increased the photoprotective effect of the ultraviolet filters mixture, presenting itself as a promising candidate in the sunscreen development field.