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Nanoparticles: shapeshifters that pass along the food chain and end up in the brain

Nanomaterials can pass much further along the food chain than was previously thought. The particles can change shape and size in each organism, enabling them to pass on to the next one in the chain. Researchers from the Institute of Environmental Sciences discovered this accidentally when using a novel method they had developed to detect nanoparticles in organisms. The research was published in Nature Communication on 9 Feb 2021.

Nanotechnology is all around us: from the chips in our computers and solar panels on our roofs, to the paint on our walls and sunscreen or moisturiser we use every day. And its use is only set to increase. Nanomaterials are (artificial) materials consisting of particles with a diameter between 1 and 100 nanometers – that is 0.0000001 to 0.00001 centimeters. These materials can easily end up in the natural world, and yet their effect on humans, animals and the environment is unknown.

New detection method

Nanomaterials are hard to regulate. This is because they are difficult to measure, Fazel A. Monikh from the Institute of Environmental Sciences explains. ‘With other chemicals you can use their mass to measure their amount in the environment or an organism. But for nanoparticles, we need to take both their physical and chemical makeup into account, so measuring their mass alone is not enough.’ Monikh and his team of international colleagues therefore developed a new method to find and trace nanomaterials in organisms.

Nanoparticles change shape

When Monikh used the new method to follow nanoparticles through a food chain – from algae to zooplankton to fish – he made a surprising discovery. The nanoparticles accumulated on the surface of the algae, and consequently entered the zooplankton in large quantities, where they then changed shape and size. And when fish ate the zooplankton, the same happened again. This enabled the nanoparticles to spread through the body in a very different way than their original shape had indicated. And in the fish, the particles accumulate in the brain, and at a higher concentration than in other tissues.

Far along the food chain

A worrying discovery, says Monikh. ‘This means that nanomaterials can pass much further along the food chain than we had previously thought.' It also makes nanomaterials even more difficult to regulate, but the new method that Monikh and his colleagues developed could open new horizons. ‘If we gain a better understanding of how these materials behave, we can also look at how to make them safe to use. And that is essential to the nanotechnology revolution.’

The research article ‘Particle number-based trophic transfer of gold nanomaterials in an aquatic food chain’ was published on 9 February in Nature Communications.

Photo above: zooplankton
Text: Marieke Epping

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