Oil encapsulation in core-shell alginate capsules generated using droplets millifluidic

PONCELET DENIS; M. PEREDA; RENARD DENIS

Congreso; 3er International EPNOE Junior Scientists Meeting; 2018

Oils are widely applied in the formulation of foods, pharmaceutical and cosmetic products; however,they are often volatile, labile and sensitive to environmental factors such as heat, light, water andoxygen [1]. An efficient strategy to decrease their sensitivity towards environmental conditionsconsists of its encapsulation in inert polymer matrix (alginate) using gelation/emulsification technique[2-4]. Specifically, the inverse gelation approach consists in adding drops of calcium chloride/oilemulsions into an alginate bath [5-7], leading to core-shell capsules with a high oil loading. Based onprevious results of our group [8], the droplets millifluidic device, where a dispersed phase isintroduced through a capillary or needle into the co-flowing continuous phase, allows the easyproduction of highly controlled and uniform microcapsules from W/O emulsions. The objective of thepresent work is, therefore, to take advantages of the new droplets millifluidic/inverse gelation basedprocess to produce core-shell alginate milli-capsules and to analyze the effect of varying the gelationtime on the final properties of the obtained capsules. Alginate was selected as the microcapsules shellgiven the non-toxic biocompatible and biodegradable properties of the gel easily formed once it reactswith divalent cations like Ca2+. It was first found as expected that alginate membrane thicknessincreased with gelation time in the collecting bath. Surprisingly, it was found that alginate membranethickness was inversely related to its mechanical properties, i.e. the thicker membrane, the lowersurface Young modulus. Surface Young?s modulus ranged from 61 to 26 N/m at gelation times of 3and 45 minutes respectively. Oil loading was quite high with 80wt% for dry capsules whatever theconditions used.