Oceans, lakes, and rivers are full of them: microplastics can now be found in almost all bodies of water. Researchers at Leibniz University Hannover (LUH) have now developed a novel material that can potentially absorb and break down microplastic particles in water independently—without any external control. The results were recently published in the renowned journal Nature Communications.
The impact of microplastics on the environment and organisms is considered one of the most pressing environmental issues of our time. These tiny plastic particles can cause inflammation and oxidative stress in living organisms. Previous methods for removing these particles have often relied on stationary filter systems, which are costly and energy-intensive to operate.
A research team led by Prof. Dr. Sebastian Polarz at the Institute of Inorganic Chemistry (ACI) at LUH has now developed an intelligent material that opens up new avenues in environmental remediation: a hydrogel that acts like a self-regulating shuttle, absorbing microplastic particles, transporting them to the water surface, and breaking them down there under the influence of light—in a repeatable, autonomous cycle.
A floating device with brains
The basic principle is simple. The hydrogel is added to the contaminated water, sinks to the bottom, collects the microplastic particles there, and rises back up to the water surface like a shuttle. There, the plastic particles are broken down, partly by the action of the sun. “Ideally, only water and CO₂ would remain,” says Dr. Dennis Kollofrath from ACI, lead author of the study. So far, the gel is still a prototype, but initial laboratory tests are promising.
The newly developed shuttle gel combines a thermoresponsive polymer, porous organosilicate particles, and a photocatalyst. At low temperatures at the bottom of the water, the polymer swells and absorbs microplastics and glucose, which is present in low concentrations in water. An embedded enzyme converts the glucose into oxygen, which is stored in the pores and gives the gel buoyancy. When enough gas is formed, it rises to the surface. “It works a bit like an underwater hot air balloon,” explains Kollofrath. At the surface, the hydrogel heats up, shrinks, and releases the gas bubbles—the buoyancy disappears and the gel sinks. At the same time, the photocatalyst produces reactive oxygen species (ROS) under the influence of light, which break down the microplastics. Through this self-regulating cycle of rising and sinking, the gel continuously cleans the water.
A flexible tool for environmental technology
“Our system combines several functions in a single material: an autonomous drive system and the absorption and targeted decomposition of pollutants – all without external control,” explains Kollofrath. The current study examined the decomposition of polystyrene as a representative example. The high adaptability of the concept is particularly noteworthy: in principle, the nanoparticles used can be modified in such a way that other pollutants—such as polyethylene or PET—can also be removed in a targeted manner.
The article was recently published in Nature Communications:
Kollofrath, D.; Kuhlmann, F.; Requardt, S.; Krysiak, Y.; Polarz, S. A Self-Regulating Shuttle for Autonomous Seek and Destroy of Microplastics from Wastewater. Nat Commun 2025, 16 (1), 6707. DOI: https://doi.org/10.1038/s41467-025-61899-4
Note to editors:
For further information, please contact Dr. Dennis Kollofrath, Institute of Inorganic Chemistry at Leibniz University Hannover, by phone at +49 511 762 1316 or by email at dennis.kollofrath@aca.uni-hannover.de.
