Conversion of Pollen Particles into Three-Dimensional Ceramic Replicas Tailored for Multimodal Adhesion

We report the first syntheses of three-dimensional (3D) nanocrystalline all-oxide replicas of pollen microparticles tailored for multimodal (bioenabled and synthetic) adhesion via use of a scalable, highly conformal surface sol-gel (SSG) coating process. High-fidelity replication allowed the pollen-shaped oxide microparticles to be utilized for adhesion via tailorable short-range (similar to 10 nm) van der Waals (VDW) attraction, with the magnitude of such VDW-based adhesion influenced by the nanoscale topography of surface features retained by the replicas. Conversion of the pollen into ferrimagnetic (Fe3O4) microparticle replicas allowed the use of magnetic attraction at short and long ranges (up to similar to 1 mm). By selecting pollen particles with particular surface features and by SSG-enabled conversion of such pollen into 3D nanocrystalline replicas composed of an appropriate type and amount of magnetic oxide, adhesive microparticles with tunable short- and long-range attractive forces can be generated.