Expanding the Particle Range for Biocatalytically Active Pickering Emulsions with Silicone Coatings

Pickering emulsions (PEs) are a particularly promising class of reaction systems for biocatalysis, typically in a water-in-oil (w/o) configuration, with a continuous organic phase and a dispersed aqueous phase containing the biocatalyst. However, only a few micro- and nanoparticles possess the intrinsic hydrophobicity necessary to stabilize such a w/o PE, which limits the application prospects. Here, silicone coatings are applied to prepare micro particles for w/o PE stabilization for the first time. The study demonstrates compatibility with available inorganic and organic materials, and the effects of silicone coatings with overall hydrophilic, amphiphilic, or hydrophobic properties on the particle size, PE formation, and the stability of the PE. Furthermore, a lipase-catalyzed transesterification in PE obtained with silicone-coated particles is performed, and the possibility to place the catalyst not only in the dispersed phase of the PE, but also on the stabilizing particles prior to coating is demonstrated. The results indicate silicone coatings as a straightforward, versatile, and tunable method for the preparation of particles with suitable properties for both the stabilization of BioPE and the immobilization of active biocatalysts.