Artificial Neptune balls: Superadhesive biomimetic networks for broad-size microplastics capture and removal

The cleanup of persistent microplastics (MPs) from aquifers requires the capture and removal of a broad range of MP sizes and shapes. Conventional methods such as filtration and centrifugation are inefficient in removing such a broad range of particle sizes. We designed a class of biomimetic cleaners inspired by natural systems-including "Sargassum rafts" that trap MPs within their branched thalli and "Neptune balls" formed from seagrass. The cleaners are in the form of porous meshes and balls made of biopolymers such as alginate and chitosan. The biopolymers are reprocessed morphologically into soft dendritic colloids (SDCs). The SDCs are consolidated in a honeycomb-like internal network surrounded by a hierarchically fibrillar outer layer. This mesh architecture enables adsorption of nano- and microscale particles via van der Waals and electrostatic interactions while physically trapping millimeter-scale particles into the net openings. Similar cleaners from architected sustainable materials could serve as scalable systems for efficient removal of diverse MPs from aquatic environments.