Microencapsulation of hydrophobic liquids in closed all-silica colloidosomes

A facile approach for the microencapsulation of hydrophobic liquids in closed solid all-silica colloidosomes is reported. The method is based on the formation of oil-in-water emulsions stabilized by silica nanoparticles and subsequent gluing of the particles at the water/oil interface by a silica precursor polymer-hyperbranched polyethoxysiloxane. By this means different oils are successfully enclosed in hence formed all-silica colloidosomes with almost 100% efficiency. Via a systematical study it is demonstrated that this process is a delicate interplay between the emulsion stability, oil polarity, and sol-gel reaction kinetics. This approach allows fabricating microcapsules of hydrophobic liquid substances in a mechanically stable, chemically inert, and biocompatible matrix, silica, with high encapsulation capacity and a controlled release profile.