Because of their minuscule size, nanoplastics—bits of plastic smaller than 1 µm—are much harder to capture from water than their bigger microplastic siblings. Researchers in Germany have now created a temperature-responsive gel that captures the tiny plastic fragments and releases them on demand with a temperature switch (Cell Rep. Phys. Sci. 2026, DOI: 10.1016/j.xcrp.2026.103257).
The gel, fashioned on the chemistry of jellyfish mucus, could be used to purify drinking or agricultural water or to treat industrial wastewater. “This is a helpful tool to capture nanoplastics from drinking water and then release them to analyze what type of plastic is in there,” says Marie Weinhart, a polymers and biomaterials expert at Leibniz University Hannover who led the study.
Microplastics are large enough to extract from water by using membrane filters or density separation, but those methods don’t work on nanoplastics. Chemist Martin Pumera at the Central European Institute of Technology, Brno University of Technology recently reported tiny magnetic machines—made of iron-based metal-organic frameworks that trap nanoplastics (Environ. Sci. Nano, 2026. DOI: 10.1039/D5EN00665A).
But Weinhart and colleagues created a passive filtration system inspired by jellyfish mucus. The high-molecular-weight mucin proteins that form mucus are amphiphilic: they have hydrophobic and hydrophilic parts, which cross-link to form 3D networks. Nanoplastics, which are hydrophobic, are attracted to the network components via electrostatic and hydrophobic forces, and the pores of the 3D network are just the right size to trap the plastic bits.
Time-lapse photographs show how a new heat-responsive gel (left) traps nanoplastic particles and settles at the bottom of the vials in 90 min (right). Credit:
Cell Rep. Phys. Sci.
To avoid using natural jellyfish mucus, which can vary in composition and has ethical implications, the researchers created a synthetic version. They stitched together hydrophilic oligo(ethylene glycol) acrylate monomers with other hydrophobic acrylate monomers to make a large amphiphilic copolymer. This copolymer self-assembles into spherical micelles with hydrophobic cores and hydrophilic shells.
In laboratory tests, the researchers added the material to water containing polystyrene nanoparticles. When they heated the water, the polymer gelled and collected 68–100% of the particles within 90 min and then settled as a clump on the bottom of its container for easy removal. Cooling the gel weakens the interactions between the polymer and the nanoplastics. A quick run in a centrifuge releases the nanoplastics for analysis or destruction, cleaning up the gel for reuse.
Weinhart says the team is planning to make the material using biobased polymers. She envisions these materials being used as surface coatings for pipes in wastewater treatment plants. “Industrial wastewater comes already at higher temperature, which is perfect for us.” The coating could trap nanoplastics, and then a quick cooling cycle “would allow easy regeneration of the coating material,” she says.
Pumera says that although his team’s magnetic machines might offer more precise microplastic and nanoplastic capture than the gel, they require magnetic removal; the gel is easier to extract. “For me, the highlight is that it’s completely a physical method, basically a temperature-controlled system. So you don’t need to add any chemical or anything to capture nanoplastics.”
Prachi Patel is a senior editor and physical sciences reporter at C&EN based in Pittsburgh.
2026 American Chemical Society
