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Projeto de investigação
Co-encapsulation of natural colorants for color and bioactivity modulation
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Developing High-Coloring Natural Systems Using Double Emulsions with Daucus carota L. Extract to Meet High-Performance Requirements
Publication . Teixeira, Liandra Gracher; Silva, Samara Cristina; Colucci, Giovana; Santamaria-Echart, Arantzazu; Peres, António M.; Dias, Madalena M.; Barreiro, M.F.
Daucus carota L. extract is attracting interest as a natural colorant alternative. However, the presence of anthocyanins (ACNs), which are sensitive to pH changes, limits its application. To tackle this issue, water-in-oil-in-water (W1/O/W2) double emulsions are emerging as innovative solutions. Nevertheless, the problem of reaching robust colorant systems for industrial use still needs to be overcome. One important target is to reach a high coloring power, minimizing its impact on the final product. In this context, the effect of colorant concentration and the volume of the primary emulsion, two routes to increase the colorant power, on color attributes and stability, an important feature to reach a marketable product, was studied. The optimal experimental design was conducted to two optimal solutions, whether through heightened colorant concentration or primary emulsion volume: a 41/59 (W1/O)/W2 ratio with 11 wt.% colorant, and a 48/52 (W1/O)/W2 ratio with 6 wt.% colorant, respectively. A subsequent assessment of color and physical emulsion stability over 30 days pointed out the solution with the lower colorant concentration (6 wt.%) as the one with better performance (L*: 44.11 ± 0.03, a*: 25.79 ± 0.01, D4;3: 9.62 ± 0.1 μm, and CI: 14.55 ± 0.99%), also minimizing the permeability of the colorant to the outer aqueous phase. Overall, these optimized emulsions offer versatile coloring solutions suitable for various industrial applications, such as food matrices and functional cosmetics.
Optimisation of stability and colouring power of double emulsion systems loaded with Daucus carota L.
Publication . Teixeira, Liandra Gracher; Silva, Samara Cristina; Colucci, Giovana; Santamaria-Echart, Arantzazu; Peres, António M.; Dias, Madalena M.; Barreiro, Filomena
Anthocyanins (ACNs) are water-soluble bioactive flavonoids found in flowers, roots, leaves, seeds, and stalks. ACNs cover a wide palette of colours, from blue and purple through orange to red1,2. They are used in the food industry (food colourant with E163 code), namely in fruit juice concentrates, nectars, jellies, yoghurts, marmalades, potato chips, ice creams, and soft drinks, replacing the synthetic Red 40 colourants. They also have diversified pharmaceutical and cosmetic uses due to their colouring and antioxidant attributes. However, their instability due to pH, light, and temperature is a major concern. This study used a double water-in-oil-in-water (W1/O/W2) emulsion technique to prevent rapid colour loss and colour variability with pH of a commercial black carrot extract (Fig. 1). A Central Composite Rotatable Design (CCRD) 22 was used to examine the effects of colourant concentration (wt%) and emulsion ratio ((W1/O)/W2) on stability
parameters (droplet size (D4,3), creaming index (CI), and colourimetric values (L*, a*). The main objective was to find an optimised formulation in terms of colourant potential and emulsion stability. Measurements were taken at 1, 7, 15, and 30 days. The optimal experimental design revealed two optimal solutions: 1) 48/52 (W1/O)/W2 ratio with 6 wt.% colorant, and 2) 41/59 (W1/O)/W2 ratio with 11 wt.% colourant. These formulations showed lower creaming index and droplet sizes with higher colourant potential. After accounting for the effect of time, the optimal condition was 6 wt% colourant concentration and 48/52 v/v (W1/O)/W2 emulsion ratio. A stable colour was maintained after 30 days (L*: 44.11±0.03, a*: 25.79±0.01, D4;3: 9.62 ± 0.1 µm, and CI: 14.55±0.99%). These findings are promising and might be applicable to produce novel colourants to be applied in several industries, such as food and cosmetics.
Timolol maleate-loaded double Pickering emulsion for the treatment of glaucoma: development, characterization, and ocular biocompatibility
Publication . Teixeira, Aniely dos Reis; Teixeira, Liandra Gracher; Schreiner, Tatiana B.; Santamaria-Echart, Arantzazu; Xavier, Viviane Flores; Silva, Gisele Rodrigues da; Barreiro, Filomena
Glaucoma is a leading cause of irreversible blindness, associated with high intraocular pressure. Topical beta-adrenergic antagonists, such as timolol maleate (TM), are first-line therapies but often have limited effectiveness due to rapid precorneal clearance and low ocular absorption. To address these limitations, a TM-loaded water-in-oil-in-water (W/O/W) double Pickering emulsion (TM-loaded DPE) was developed to enhance corneal retention, sustain drug release, and enhance ocular bioavailability. The TM-loaded DPE consisted of a primary W/O emulsion prepared from TM solution and mineral oil, stabilized by soy lecithin, combined with an external aqueous phase containing chitosan-Hydroxypropyl methylcellulose (chitosan-HPMC) particles as Pickering stabilizers, to form a W/O/W emulsion. Chitosan-HPMC particles had a size of 1.02 ± 0.16 μm, a zeta potential of 36.20 ± 2.41 mV, and a contact angle of 78.47 ± 1.80°, making them suitable Pickering stabilizers. The TM encapsulation efficiency in the TM-loaded DPE was 96%, indicating the high loading capacity of the developed system. Confocal laser scanning microscopy revealed a mononuclear droplet morphology, and the system exhibited excellent macroscopic physical stability under refrigerated conditions (4 °C, 12 months), as corroborated by the creaming index test, despite slight signs of coalescence observed in microscopic analysis. Rheological testing confirmed a non-Newtonian and shear-thinning behavior. The formulation achieved approximately 84% TM release over 48 h, indicating sustained release. The Hen egg test chorioallantoic membrane (HET-CAM) assay indicated no irritation potential, confirming its safety. Overall, these results highlight TM-loaded DPE as a promising drug delivery system for glaucoma treatment, offering improved drug retention and enhanced ocular bioavailability.
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Fundação para a Ciência e a Tecnologia
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2020.08803.BD