MCT oil and surfactant were removed from the submicron beads
for SEM analyses. Even without a surfactant present the alginate
submicron beads could be re-suspended in hexane after centrifugation.
This confirms that the submicron beads must be in a gelled
state and CaCl2 nanoparticles migrate to the emulsion droplet
interface, where they dissolve into the aqueous alginate phase and
cause gelation (if the submicron beads would still be in a liquid
state the alginate submicron beads would coalesce in the absence
of a surfactant, especially during centrifugation, and no separate
alginate submicron beads would be observed with SEM). Auger
Electron Spectroscopy was also used to determine if the elements
calcium and chlorine were present in the submicron beads. Typical
results from Auger Electron Spectroscopy are listed in Figs. 4 and 5.