A Korea-born scientist in the United States developed a net that, inspired by seaweeds and seagrasses in the ocean, captures microplastics of all sizes. Nature has provided a way to eliminate microplastics, which have worn down not only ecosystems but also humans.
Orlin Velev, a professor in the Department of Chemical and Biomolecular Engineering at North Carolina, and a team led by researcher Hong Hye-rin said on the 5th (local time) that they "developed a net that captures microplastic particles of various sizes in fresh and seawater by mimicking how microplastics get entangled in seaweeds and seagrasses." The findings were published as the cover paper in the July 7 issue of the international journal Science Advances.
An estimated 8 million tons of plastic waste flow into the ocean each year worldwide. Microplastics are those that do not decompose but only shrink to 5 mm or less. They are found across the globe, from the deep sea to the Arctic and Antarctic and the high Alps, and they also appear in the food and water we consume and in everyday products. There are concerns that microplastics, when small enough, can pass through the blood-brain barrier (BBB) and even cause dementia and stroke.
◇ Inspired by sargassum rafts and seagrass leaf balls
Researcher Hong Hye-rin developed a mesh that can capture a wide range of plastic particles at once, from nanometers (nm; one-billionth of a meter) to millimeters (mm), inspired by how plastic waste and particles get entangled in sargassum rafts drifting at sea and Neptune balls found on beaches.
Sargassum, a brown alga, has air bladders that allow it to float on the sea like a massive raft. In the process, it tangles with and traps plastic waste and particles. Neptune balls are formed when leaves shed from the seagrass Posidonia oceanica are abraded by waves, leaving only tough fibers that clump into a ball. Because Posidonia derives from Poseidon, the sea god in Greek mythology, they are called Neptune balls using the Romanized form.
The team built the net structure from the natural polymers alginate and chitosan. Alginate comes from brown algae such as kelp or sea mustard, and chitosan comes from chitin, a glycoprotein complex found in crab shells and shrimp shells. A benefit is that the materials can recycle waste from seafood processing.
First, they created a soft, resinous, highly branched colloid from alginate. This material has microfibers stretching in all directions, giving it an enormous surface area, which makes contact with other substances easy. After freeze–thaw processing, the interior becomes dense and firm as the colloid compacts, while the surface exposes the branches. Finally, they coated the microbranch surfaces with positively charged chitosan. As a result, it bonds very strongly with surrounding materials, like the pads of a gecko's feet or a spider's silk.
The researchers confirmed with their natural-polymer net that they could capture microplastics of various sizes in seawater collected from an actual beach. Velev said, "Particles 1 mm and larger get caught in the net, and very small particles in the tens of nanometers can be captured by an adhesive mechanism." In effect, the net coated with a powerful adhesive is lowered into the ocean to catch all the microplastics.
◇ Concept for a robot vacuum that catches microplastics also proposed
The biomimetic net is expected to significantly aid microplastic removal, as nature does. Spanish scientists reported in 2021 that Neptune balls capture 1,500 plastic fragments per kilogram. The team at the time estimated that Neptune balls could capture 900 million plastic particles annually. Hong said the new work does not simply mimic nature, but rather reengineers it to boost performance.
Last year, Hong also developed a system that dives into the sea to seize plastic particles and then resurfaces. It uses the same material as this net but differs in being mobile. After capturing plastic particles, it rises with bubbles generated when magnesium meets water. Hong said, "If last year we proposed the concept of a robot vacuum that captures microplastics, this time we increased commercialization potential further by using a net that mimics natural structures."
For a microplastic-catching net to be commercialized, it must be verified that it can be used stably over long periods in the ocean or rivers. It also needs to be confirmed whether it can capture particles even when microorganisms proliferate on microplastic surfaces to form a film called a biofilm. Another task is to develop a mass-production process to secure economic viability. Hong said, "If follow-up research proceeds, we can expand its applications beyond environmental cleanup to various fields such as industrial wastewater treatment and water treatment."
First author Hong graduated from Sungkyunkwan University and earned a master's degree at the same graduate school. Hong went to study at North Carolina in 2020 and received a doctorate in May. Kim Byung-gon, a doctoral researcher from Kyungpook National University, was also listed as a co-author on the paper.
References
Science Advances (2026), DOI: https://doi.org/10.1126/sciadv.aeg0819
Advanced Functional Materials (2025), DOI: https://doi.org/10.1002/adfm.202423494
Scientific Reports (2021), DOI: https://doi.org/10.1038/s41598-020-79370-3