Preparation of ellipsoid-shaped supraparticles with modular compositions and investigation of shape-dependent cell-uptake

Hybrid colloidal supraparticles often show a superior performance in catalysis, optics and biomedicine thanks to the synergistic effect of the ensemble of their single nanoparticle building blocks. Despite the emerging importance of shape-dependent properties of nanostructures, the synthesis of supraparticles is generally limited to a spherical shape. Here, a broadly applicable method is presented for the fabrication of ellipsoid supraparticles from one or several types of inorganic nanoparticles in various compositions. The method is highly versatile and modular, allowing free choice of hydrophobic nanoparticles to combine desired properties in the resulting supraparticles. A representative series of ellipsoid-shaped supraparticles is fabricated and their morphology, hybrid structure and composition as well as their functional properties are investigated. All employed nanoparticle types are successfully incorporated resulting in ellipsoid-shaped supraparticles with largely homogeneous intra-and interparticular distribution of the different nanoparticle building blocks. A biological assessment of iron oxide ellipsoid supraparticles reveals no safety issues but a pronounced lower cellular uptake compared to spherical ones. This distinct shape-property relationship illustrates the importance of the supraparticle shape as a parameter for the rational design of nanosystems for biomedical applications.