J.-P. Douliez, A. Perro, J.-P. Chapel, B. Goudeau and L. Béven
A template-free all-aqueous bulk preparation of robust hollow capsules having a gelatin shell from all-in-water double emulsions is reported. The hot (>40 °C) quaternary system water/polyethylene glycol (PEG)/gelatin/ alginate is shown to spontaneously form PEG-in-gelatin-in-PEG double water emulsion droplets having a multinuclear core. These droplets are stable upon cooling below the temperature at which gelatin gelled. In contrast, above the melting temperature of gelatin, multinuclear double emulsion droplets controllably evolve into stable mononuclear yolk (aqueous PEG)- shell (gelatin) capsules dispersed in the aqueous PEG continuous phase. It is demonstrated that the gelatin shell can accommodate negatively charged latex beads and be re-enforced by glutaraldehyde or silica. These capsules are also shown to encapsulate payloads, suggesting possible applications in microencapsulation, drug delivery, and synthetic biology.