Spontaneous Fusion of Core-Shell Nanocapsules with Oil Cores and Oppositely Charged Polysaccharide Shells

Polymer nanocapsules with hydrophobic cores are promising candidates for nanoreactors to carry out (bio)chemical reactions mimicking the performance of natural cellular systems. Their architecture allows reagents to be encapsulated in the cores enabling reactions to proceed in confined environments in a controlled, and efficient manner. Polysaccharide-shell oil-core nanocapsules are proposed here as facile mergeable nanoreactors. Spontaneous fusion of oppositely charged polysaccharide capsules is demonstrated for the first time. Such capsules are formed and easily loaded with reagents by nanoemulsification of an aqueous solution of hydrophobically modified polysaccharides (chitosan, hyaluronate) and oleic acid with dissolved desired hydrophobic compounds. Efficient fusion of the formed nanocapsules dispersed in an aqueous medium at optimized conditions (pH, ionic strength) is followed using fluorescence microscopy by labeling both their cores and shells with fluorescent dyes. As a proof of concept, a model fluorogenic synthesis is also realized by fusing the capsules containing separated reagents and the catalyst. The nanocapsules and fusion process developed here establish a platform for realization of versatile reactions in a confined environment including model studies on biologically relevant processes taking place in natural systems.