New method for assessing the toxicological effects of nanoparticles on algae


The steady increase in industrial applications and the associated release of artificially produced nanomaterials into the environment requires methods for assessing the effect of nanomaterials on ecosystems. Olivier Martin and his team have developed an optical biosensor to measure the environmental influences of nanomaterials on living organisms.

Background (completed research project)

Studies have shown that artificially produced nanomaterials may have a toxic effect on bacteria, algae and cells of higher organisms and thus entail risks for humans and the environment. New methods are needed to adequately examine these risks. In this project, Olivier Martin and his team developed a biosensor that can measure the effect of nanomaterials on aquatic micro-organisms. If a substance is toxic to an organism or a cell, it triggers a stress response in the cells and the cell will be damaged over time. Under stress, the cells excrete specific substances, known as reactive oxygen compounds (ROC), which can be measured. One such ROC compound is hydrogen peroxide. Olivier Martin and his research team grew the green algae Chlamydomonas reinhardtii in different concentrations of TiO2 and CuO nanoparticles and analysed the amount of hydrogen peroxide produced by the algae. This was done using a protein (cytochrome c) that reacts with hydrogen peroxide by changing its colour. The greater the amount of hydrogen peroxide measured in this fashion, the greater the stress triggered in the algae by the nanomaterials.


The results showed that nanomaterials can trigger a stress response in aquatic micro-organisms. The reaction of the green algae was highly dependent on the type of nanomaterials and their concentration. The conditions under which the organisms were exposed to the nanomaterials also played an important role. It became evident that environmental conditions, which are usually ignored, such as luminosity, also play a role. Overall, the researchers found that nanomaterials only cause stress reactions in green algae in very high concentrations. No toxic effects were measured at concentrations that are currently realistic in the environment.


The biosensor established in this project offers a very sensitive tool for measuring the environmental impact of nanomaterials on living organisms under different conditions and for comparing the results. As the measurement is performed on living green algae, it is possible to track the stress response over a long period of time or observe whether the green algae are also able to recover from the toxic effect over time. The biosensor, which has meanwhile been patented, is a decisive step towards a reliable determination of environmental risks caused by nanomaterials.

Original title

Non-invasive continuous monitoring of the interaction between nanoparticles and aquatic microorganisms

Project leader(s)

  • Prof. Olivier Martin


  • Prof. Paul Bowen
  • Prof. Vera Slaveykova-Starcheva



Further information on this content


Prof. Olivier Martin Laboratoire de nanophotonique et métrologie
1015 Lausanne +41 21 693 26 08