Fractal-in-a-Sphere: Confined Self-Assembly of Fractal Silica Nanoparticles

Fractal objects such as snowflakes and trees are ubiquitous in nature. However, fractal nanoparticles with uniform morphology and controllable structures are difficult to make. Herein, using a fractal-in-a-sphere strategy, we report the confined self-assembly of fractal silica nanoparticles with tunable fractal generations and uniform sizes. One advantage of controllable fractal generations has been demonstrated in enzyme delivery for parasite oocyst control. The fractal silica nanoparticles exhibited better oocysticidal performance compared with nanoparticles of other structures due to combined effects of enhanced adhesion, penetration across the oocyst wall, and high local enzyme concentrations. This study paves the way for the fabrication of fractal silica nanoparticles with fine structures and versatile applications.