Water-in-water emulsions for obtaining enzyme-loaded microgels and encapsulated emulsions
- Autores: Yoran Beldendrün
- Directores de la Tesis: Jordi Esquena Moret (dir. tes.), María José García Celma (tut. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Andrea Pascucci (presid.), Elvira Escribano Ferrer (secret.), Carlos Rodríguez Abreu (voc.)
- Programa de doctorado: Programa de Doctorado en Investigación, Desarrollo y Control de Medicamentos por la Universidad de Barcelona
- Materias:
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- Resumen
Encapsulation of enzymes into protective matrices is of interest in drug delivery or industrial processes, to control the release of the enzyme or protect it from harsh environments. We are studying the encapsulation of lactase (β-Gal) into drug delivery vehicles, templated by water-in-water (W/W) emulsions.
In the first system, the sodium carboxymethylcellulose (NaCMC) / bovine serum albumin (BSA) mixtures, phase behavior was analyzed and emulsions were formed. Ca2+ crosslinked selectively NaCMC, while the trivalent ions Fe3+ and Al3+ crosslinked both polymers, thus also the entire emulsion. By dropping the emulsion into the trivalent crosslinker solutions, encapsulated emulsions could be obtained, which consist of BSA gel beads that contain encapsulated NaCMC emulsion droplets. Freeze-drying of those beads lead to particles with pores, whose size corresponded to that of the emulsion droplets. Bead size was minimized by using the electrospraying technique. Stability of those encapsulated emulsions and incorporation of enzymes into them was studied.
In the second system, the gelatin/maltodextrin mixtures, phase behavior was analysed in detail. Microgels were formed from the gelatin-in-maltodextrin emulsions by cooling and crosslinking the gelatin droplets with genipin. Those microgels could also be kept in a dry form, obtained by freeze-drying the suspension. Responsiveness and stability of microgels under various physicochemical conditions was studied. Next, various immobilisation methods of the enzyme β-Gal were tested, to achieve highest encapsulation yield and activity recovery. Enzymes remained active over at least one month inside the microgels and enzyme-leakage decreased at higher crosslinking rates. Of interest is the fact that the enzyme remained active after a complete cycle of freeze-drying and rehydration of enzyme-loaded microgel particles.
The crosslinked gelatin microgels were not able to preserve enzyme activity under simulated gastric fluid temperature and pH conditions. It was shown however that they have protective effect on enzyme activity at pH 5.8 and 37 °C. These can be considered as preliminary results for their possible use in e.g. industrial production of lactose-hydrolyzed milk, which has similar pH and temperature conditions.
