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Killing cancer cells with metals and light

Thursday 21 March 2019
Niels Bohrweg 2
2333 CA Leiden
De Sitter room


Can't attend the lecture? View the live stream this evening or afterwards!

Making tumours disappear by shining a light on them? This could be the future. By adding light-sensitive molecule groups to cancer medicines, their cancer-destructing effect can be switched on in specific areas of the body. The severe side-effects of chemotherapy would belong to the past.

In this lecture, chemist Sylvestre Bonnet will show how chemotherapeutics can be turned into body-friendly medicines, destroying only tumor cells by shining visible light on them. This could be the solution for inoperable tumours around the nerves or brain, or in the biliary tract.

Light-sensitive particles

Photoactivated chemotherapeutic (PACT) compounds are metal complexes: molecules that consist of a positively charged metal ion and one or more electron-rich organic molecules. Metal compounds are often very toxic and can therefore be used to combat cancer. However, these metal ions are not selective and destroy not only tumor cells, but also healthy tissue.

To tackle this problem, a light-sensitive protective molecule group is added to the metal complex. In the presence of blue, green, or red light, this groups detaches itself, making the metal toxic again. By only illuminating the tumour, the harmful effects of the metal complex are limited to the tumour. This is in essence chemotherapy and radiotherapy combined, but without the side-effects.

New approach for chemists

Research into PACTs has always focused on finding suitable chemical compounds and  assessing their photochemistry. To develop medicines that will benefit cancer patients, chemists must radically change their research approach. Switching from conducting traditional chemical research to thinking like pharmacologists and oncologists. How can this paradigm shift be accomplished?

Sylvestre Bonnet

About Sylvestre Bonnet

Sylvestre Bonnet obtained his PhD degree on molecular machines at the University of Strasbourg, France in 2007. He then moved to The Netherlands as a postdoctoral fellow. After a year at Utrecht University where he obtained a Veni grant, he came to Leiden University. In 2012 he received a Vidi grant, followed by an ERC Starting Grant in 2013, and recently a Vici grant in 2019. Since three years he is an associate professor at the Leiden Institute for Chemistry. His expertise lies at the intersection of bioinorganic chemistry, photochemistry, cancer science, and liposome technologies. His current research interests are light-activated anticancer metallodrugs, photocatalysis, and liposome technologies.


In Febrary 2019 Sylvestre Bonnet received a Vici grant of 1,5 millions euros for his research. Read more about this is in Vici for Sylvestre Bonnet: new light on cancer therapy.


For almost 150 years, the Natuurwetenschappelijk Gezelschap Leiden has been organising high-quality scienctific lectures with renowned scientists at Leiden University. Each year at least one of these lectures is in English. Alumni, (former) employees and all other parties interested in the natural sciences are very welcome to attend.


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