Preparation of Multicore Colloidosomes: Nanoparticle-Assembled Capsules with Adjustable Size, Internal Structure, and Functionalities for Oil Encapsulation

Colloidosomes, also known as Pickering emulsion capsules, have attracted considerable attention for encapsulation of both hydrophilic and hydrophobic actives. However, current preparation methods are limited to single core structures and require modified/engineered nanoparticles for forming the capsules. Here, a simple, safe, and highly versatile approach for producing multicore colloidosomes from non-modified nanoparticles is reported. Multi-oil core silica colloidosomes are prepared at room temperature via salt-driven assembly of cheap hydrophilic nanoparticles dispersed within a double (O/W/O) emulsion template. The internal structure and overall diameter of the final capsules can be adjusted by altering the primary and secondary emulsification conditions. With this approach, 7 to 35 µm diameter capsules containing 0.9 to 4.2 µm diameter multiple oil cores are produced. Nanoparticles such as Fe3O4, TiO2 and ZnO can easily be incorporated within the structure, conferring magnetic and photocatalytic properties to the capsules, enabling degradation of Rhodamine B under UV-light irradiation as well as magnetic capture. These capsules can also be used to entrain hydrophobic dye (Nile red), with ultrasound rupturing serving as a facile method for accessing the internal core environments. This work offers a promising approach for producing tunable multifunctional microcapsules for oil encapsulation.