New sensor detects blue-green algae toxins in Swiss lakes

New sensor detects blue-green algae toxins in Swiss lakes Keystone-SDA

A new sensor, developed by researchers at the Swiss Federal Institute of Technology in Lausanne (EPFL), detects harmful cyanobacterial toxins molecule by molecule, the university announced on Monday.

As soon as water temperatures rise in summer, blue-green algae often spread rapidly in bodies of water. They release dangerous toxins – known as microcystins – which pose a risk to bathers, dogs and the drinking water supply.

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As there are over 300 different variants of these toxins, water quality monitors have previously faced a dilemma: while rapid tests provide quick results on site, they are largely unable to distinguish between the individual toxin variants. Laboratory analyses, on the other hand, are highly precise but require specialised equipment weighing several tonnes, trained staff and a waiting time of days to weeks.

A portable measuring device as the goal

This is where the development by the research teams led by Matteo Dal Peraro and Tamar Kohn, presented in the specialist journal ACS Nano, comes in. At the heart of the sensor is a so-called nanopore – a tiny channel made of the protein aerolysin, which is just one nanometre wide at its narrowest point.

When an electric voltage is applied, charged particles flow evenly through the pore. If a single toxin molecule passes through the channel, it blocks it for a fraction of a second. As each of the different toxins slows the flow of current to a different extent depending on its size and structure, a characteristic electrical fingerprint is created.

In the laboratory, the team was able to distinguish seven closely related microcystin variants beyond doubt using this method. According to the researchers, the system is already effective at concentrations 40 times below the WHO guideline value for drinking water.

At present, the water samples still need to be manually filtered and prepared before measurement. However, the researchers’ long-term goal is to develop a portable measuring device that can be used directly on the shore or on a boat.

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Translated from German, reviewed by an English Department journalist.