Development and characterization of encapsulation systems for the protection and controlled release of active agents

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Pickering emulsions stabilized with chitosan/collagen peptides nanoparticles as green topical delivery vehicles for cannabidiol (CBD)

Publication . Sharkawy, Asma; Silva, Ana Margarida; Rodrigues, Francisca; Barreiro, M.F.; Rodrigues, Alírio

Pickering emulsions (PEs) are attracting increasing attention in the areas of food, cosmetic and pharmaceutical applications owing to their surfactant-free and eco-friendly nature. Herein, PEs stabilized by chitosan/collagen peptides (CH/CP) nanoparticles were assessed as green surfactant-free vehicles for the topical delivery of cannabidiol (CBD), a highly lipophilic unstable drug that is finding an increasing appeal in the cosmetic market. The influence of the oil phase volume fraction (φ) and the oil type on the emulsion properties, stability, rheological properties, as well as on the ex-vivo skin absorption of CBD was evaluated. The PE prepared with olive oil (φ = 0.6) exhibited elastic gel-like properties and demonstrated long-term stability after 5 months of storage, with a CBD content of 99.45% of the initially added amount. The skin absorption studies showed that CBD was retained in high amounts in the stratum corneum, while the CBD skin permeation was extremely low, indicating that the produced formulations are suitable as topical delivery vehicles. ATR-FTIR examination of the treated skin samples confirmed that the produced PEs were able to overcome the stratum corneum barrier. These findings suggest that the PEs stabilized with CH/CP nanoparticles provide an effective surfactant-free alternative for the topical delivery of CBD.

2021Journal article

Open access

Pickering emulsions stabilized with chitosan/gum arabic particles: effect of chitosan degree of deacetylation on the physicochemical properties and cannabidiol (CBD) topical delivery

Publication . Sharkawy, Asma; Barreiro, M.F.; Rodrigues, Alírio

Pickering emulsions (PEs) have recently gained increasing attention as green carriers of bioactive agents due to their surfactant-free and eco-friendly nature. Herein, the effect of the degree of deacetylation (DDA) of chitosan on the properties of chitosan/gum Arabic (CH/GA) particles and PEs was investigated. CH/GA particles with a DDA of 96% (high DDA) and 78% (low DDA) were prepared. The contact angle of water drop for the CH/GA particles prepared with high and low DDA chitosan was 84.2 and 77.5 , respectively. The dynamic interfacial tension of the particles has shown lower values with high DDA chitosan. The high DDA PE formulation exhibited higher stability after two months of storage than its counterpart prepared with low DDA chitosan. The mean emulsion droplet size was 15.6 ± 4.3 mm and 21.1 ± 2.6 mm for PEs prepared with high and low DDA chitosan, respectively. Both PE formulations demonstrated shear thinning and elastic gel-like properties. The amount of cannabidiol absorbed by the stratum corneum, viable epidermis and dermis was significantly higher in both PE formulations than the permeated amount, but no significant difference was observed between the amounts absorbed from both formulations.

2022Journal article

Open access

Chitosan-based Pickering emulsions and their applications: A review

Publication . Sharkawy, Asma; Barreiro, M.F.; Rodrigues, Alírio

Pickering emulsions, which are emulsions stabilized by solid particles, have gained increased research interest owing to their eco-friendliness and high stability. Among a wide range of solid particles, chitosan particles and chitosan-based particles have become attractive candidates as Pickering stabilizers due to their biodegradable, biocompatible and nontoxic properties. This review aims to provide an insight into the recent advances in the production and physicochemical properties of these systems. Moreover, this paper highlights the research progress in employing chitosan-based Pickering emulsions in different application areas, such as food and cosmetic applications, and environmental research. Chitosan-based Pickering emulsions have opened new avenues for the designing and production of innovative materials. The review also sheds light on the novel materials that are synthesized from these Pickering emulsion systems. Future research directions and opportunities on these promising Pickering systems are also addressed.

2020Journal article

Restricted access

New Pickering emulsions stabilized with chitosan/collagen peptides nanoparticles: Synthesis, characterization and tracking of the nanoparticles after skin application

Publication . Sharkawy, Asma; Barreiro, M.F.; Rodrigues, Alírio

Pickering emulsions based on biopolymeric particles are gaining increasing research recognition in numerous applications due to their biocompatibility and eco-friendliness. In this work, chitosan/collagen peptides nanoparticles were applied to stabilize Pickering emulsions for potential cosmetic applications. The nanoparticles had a contact angle of 78.02° ± 2.04°, reflecting their hydrophilic nature. Their average size and zeta potential were 32.27 nm and +59.7 mV, respectively. Confocal laser scanning microscopy (CLSM) showed that the nanoparticles become well-adsorbed at the oil-water interface. The emulsions displayed shear-thinning viscosity and gel-like texture. Their average droplet size ranged between 7.63 μm and 15.72 μm. CLSM skin tracking of the nanoparticles, after ex vivo skin application of the Pickering emulsions, revealed the ability of the emulsion droplets to penetrate the stratum corneum and deposit in deeper skin layers. The penetration degree depends on the concentration of the nanoparticles in the emulsion and on the contact time with the skin. These results provide new insights into the fate of the nanoparticles used to stabilize Pickering emulsions following their skin application.

2021Journal article

Open access

Enhancing trans-resveratrol topical delivery and photostability through entrapment in chitosan/gum Arabic Pickering emulsions

Publication . Sharkawy, Asma; Casimiro, Filipa M.; Barreiro, M.F.; Rodrigues, Alírio

The surfactant-free nature and higher stability of Pickering emulsions make them preferable solutions over conventional emulsions for skin applications. In this work, Pickering emulsions stabilized by chitosan/gum Arabic (CH/GA) nanoparticles were tested as vehicles for trans-resveratrol topical delivery. Skin absorption was examined ex vivo using Franz diffusion cells and porcine skin. Pickering emulsions allowed higher cutaneous retention and lower permeation of resveratrol, in comparison with a control solution based on a 20% v/v ethanol. The total amount of resveratrol retained in the skin, 24 h after the application, was 11.60% and 10.82% of the applied dose for the tested Pickering emulsion-based formulations prepared with 0.5% and 1.5%w/v CH/GA nanoparticles, respectively. In contrast, resveratrol skin retention from the control solution was only 2.86%. Confocal laser scanning microscopy revealed enhanced skin deposition of Nile Red to deeper layers from the Pickering emulsionbased formulations. Moreover, Pickering emulsions led to trans-resveratrol photostability increase, as measured after exposure to UV for 4 h. These results show that the CH/GA Pickering emulsions are promising solutions for the topical delivery of trans-resveratrol and have the potential to be used as green cosmetic products.

2020Journal article

Open access