Universiteit Leiden

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Speed gun for molecules

Detecting molecules with temperature instead of chemical reactions: that’s what scientists from the Leiden Institute of Physics want to do. They are developing a sensor that utilizes special nanoparticles to keep track of certain molecules. In this way, they can for example see how well new drugs do they’re job. Martin Baaske received a Marie Sklodowska Curie grant to start the project.


The new method focuses on plasmonic nanosensors. These are nanosized metal particles that change frequency when molecules get close to them. They are important tools in the field of biochemical sensing, to detect specific molecules of interest. Ideally, they can be used to check if and how well newly developed drugs interact with the target molecule they are aimed on in the body. Baaske will use the Marie-Curie grant to develop a new probing technique, using warmth instead of chemical reactions.

Tuning fork

Baaske explains how the traditional method works: ‘just like a tuning fork, these metal particles exhibit a resonance frequency. This frequency can be probed with visible or near infrared light. The resonance frequency changes if the molecules of interest get close or bind to the metal particle. This allows researchers to detect them.’


However, the frequency shifts alone are in most cases not sufficient enough to discriminate between different molecules. Researchers address this problem by covering the metal particles with chemical agents that only catch molecules of interest. This step is called surface functionalization and is very cost intensive. Moreover, the target molecules are often not released by the agents after binding. Therefore, the individual nanoparticles become useless once every agent has caught a molecule.

For this reason, Baaske and his team now aim to develop a new sensor that utilizes plasmonic nanoparticles to detect freely moving molecules, thus avoiding the detrimental effects and costs associated with the traditional method.

Speed gun

The new sensor will measure the temperature driven movement , so the kinetic properties, rather than the chemical properties of molecules in order to identify them. Normally the concentration of all molecules in solution is constant everywhere. If there is a temperature gradient  it will alter the concentration of molecules. Some molecules like the heat and will accumulate more around the heat source, while others will flee this region. Once heated, their diffusive speed will thus change. Exactly those changes Baaske is going to measure. ‘Essentially our sensor will act like a very small and very fast speed gun for molecules’, Baaske adds.

The Marie Skolodowska Curie actions (MSCA) are an initiative of the European Commission. The MSCA provides scholarships to make it more attractive for researchers to work in Europe. The scholarships are suitable for researchers who want to work abroad. Individual researchers, researchers at knowledge institutions or companies can apply for a scholarship. Organisations and companies that want to hire a researcher from abroad can also apply for a scholarship. An amount of € 5.6 billion has been made available for the period 2013-2020.

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