Novel biocompatible microgels for functional food, obtained in water-in-water emulsions.

Abstract

The aim of this study is to prepare microgels obtained from water-in-water (W/W) emulsions, which could be used as a drug delivery vehicle of different active ingredients. Microgels are colloidal dispersions of cross-linked gel particles with the ability to swell in response to a change of physicochemical parameters (pH, temperature, ionic strength, etc.). In the last few years, microgels have been investigated due to their biocompatibility, their high water content and their use of biocompatible polymers such as proteins and polysaccharides. Moreover, their controlled drug release at the target site improves the drug efficacy and reduces side effects. The (W/W) emulsions have been formed by a dispersion of an aqueous phase into another aqueous solution. Two mutually immiscible hydrophilic polymers have been used. As other emulsions, (W/W) emulsions are no thermodynamically stable. In the present work, the phase behaviour of the system Carboxymethylcellulose (CMC) – Bovine serum albumin (BSA) mixtures has been was studied at two different pH conditions: neutral and basic. At neutral pH, coacervates were formed and it was not possible to obtain emulsions. However, at basic pH, an immiscibility region with coexistence of the aqueous phases was detected. The respective phase diagram could be drawn and water-in-water (W/W) emulsions were prepared. The emulsion droplets were relatively stable and could be examined under the optical microscope. They presented instability by coalescence, which was reduced by decreasing pH. Emulsions behaviour, which were composed of CMC droplets neutralized with acid, was studied. CMC gels have been cross-linked with Fe3+ ions, and capsules and beads, made of cross-linked CMC, have been obtained.