Microfluidic approach to produce emulsion-filled alginate microgels

Carrying lipophilic compounds protection within alginate microgels is a challenge, mainly due to the necessary oil-core matrix. Based on this demand, this study aimed to evaluate the use of glass microfluidic devices to produce emulsion-filled alginate microgels and understand the effect of process variables on microgels size and polydispersity. Firstly, stable and monodisperse size-distributed oil microdroplets were formed by preparing an oil-in-water (O/W) emulsion using high shear followed by ultrasound. The continuous aqueous phase was composed of Na-alginate, cellulose nanocrystals and ultrafine calcium carbonate. Sunflower oil composed the emulsion oil phase (10%, w/w). Secondly, oil-in-water-in-oil (O/W/O) emulsions were formed within microfluidics devices to obtain emulsion-filled hydrogel particles. The previously produced O/W emulsion was introduced as the dispersed phase into a continuous phase containing sunflower oil, PGPR and acetic acid. The aqueous phase was gelled by internal gelation, promoting the alginate network. Monodisperse particle size distribution was observed, with a coefficient of variation lower than 6% and mean size ranging from 259 to 526 μm. Microgels size was influenced by the viscosity of O/W emulsion and the phases flow rates. Our results show the potential of microfluidic processes for producing microgels and filled microgels to encapsulate lipophilic compounds. •Emulsion filled alginate microgels was formulated in microfluidic devices.•Phases' composition was studied before being used in microchannels.•O/W emulsion composed the dispersed phase, and sunflower oil, PGPR, and acetic acid the continuous phase.•Dispersed phase viscosity and both phase flow rates affected the microgels size.•Higher Qc/Qd produced smaller alginate microgels size and emulsion filled alginate microgels particles.