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Sustainable production of porous chitosan microparticles by energy-efficient membrane emulsification
Publication . Mondal, Suchintan; Tavares, Márcia T.; Brazinha, Carla; DQ - Departamento de Química; LAQV@REQUIMTE; Elsevier
In drug delivery, it is common to use porous particles as carrier media, instead of dense particles, due to their high specific surface area and available entrapment volume, which allows a higher amount of drug to be encapsulated and then released. Chitosan microparticles are extensively used in drug delivery, but porous chitosan microparticles are scarcely reported. In this work, the preparation of porous chitosan microparticles using membrane emulsification is addressed, a technology that involves mild operating conditions and less energy consumption than traditional methods (such as ultrasound), and with higher control of the particle size. The dense structure is obtained by a water-in-oil emulsion. The porous structure is obtained by a gas-in-water-in-oil G/W/O double emulsion, where argon bubbles get entrapped in an aqueous chitosan solution that is further emulsified in a paraffin/petroleum ether mixture. Porous chitosan particles were obtained with sizes of 7.7 ± 1.6 μm, which was comparable with dense chitosan particles (6.2 ± 2.3 μm). The pore structure was optimized by varying the argon flow rate, being optimized at 0.24 L h−1. The impact of drug loading by adsorption or encapsulation, and of the drug release behaviour when using porous and dense particles were assessed, using the protein bovine serum albumin (BSA) as a model drug. The results showed that by encapsulating BSA the loading efficiency was above 95 % for both types of particles, with the release being slightly slower for the dense particles. As for the adsorbed BSA, the loading efficiency was significantly higher for porous particles – 70 % - against the 40 % for dense particles. Porous chitosan particles were successfully obtained using the membrane emulsification technology and showed that these carriers are advantageous regarding drug loading and release.
Sustainable production of nanoemulsions by membrane-assisted nanoemulsification using novel aroma-based hydrophobic deep eutectic solvents for enhanced antifungal activities
Publication . Mondal, S.; Syed, U. T.; Pinto, E.; Leonardo, I. C.; Romero, P.; Gaspar, F. B.; Crespo, M. T. Barreto; Sebastian, V.; Crespo, J. G.; Brazinha, C.; DQ - Departamento de Química; LAQV@REQUIMTE; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); Elsevier
Hydrophobic deep eutectic solvents (DESs), a recent class of green solvents, offer 100% atom economy, low cost, potential biodegradability, negligible toxicity and promising bioactivities. In this work, novel aroma-based therapeutic hydrophobic DESs were prepared and dispersed in aqueous media as nanoemulsions to potentiate biomedical applications, where polar media is encountered. A reusable microengineered stainless-steel isoporous membrane was fabricated by laser drilling technique. Three hydrophobic DESs, namely DES A (menthol and vanillin), DES B (menthol and raspberry ketone), and DES C (thymol and raspberry ketone) were prepared and emulsified in aqueous media by sustainable membrane emulsification technique. The optimised nanoemulsion (DES C-in-water) exhibited a monomodal size distribution with Zavg (size average) of 147 nm and polydispersity index of 0.22. From the application perspective, the formulated DES-in-water nanoemulsions and their constituents were evaluated for their antibacterial properties against Escherichia coli and Staphylococcus aureus. Additionally, antifungal properties of the DES-based emulsions were reported for the first time by testing them against four fungal strains, Aspergillus fumigatus, Candida albicans, Candida krusei, and Trichophyton mentagrophytes. The nanoemulsions were found to be exhibit antimicrobial effect and lesser quantities of individual compounds were needed in nanoemulsified state to show similar effects. Different 1D and 2D NMR techniques were successfully used to investigate the structural orientation and the inter and intramolecular interactions in the DES and emulsion systems, which revealed a probable cause for higher antimicrobial activity of DES C-based emulsions compared to its peers. Lastly, a synergistic effect of the components in nanoemulsions led to enhanced antimicrobial activities.
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Fundação para a Ciência e a Tecnologia
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OE
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SFRH/BD/146967/2019