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 (∼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 (Fe 3 O 4 ) microparticle replicas allowed the use of magnetic attraction at short and long ranges (up 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.