Published on 29 July 2019
Research

A professor-researcher at the Physical Chemistry Laboratory (LCP - CNRS/Université Paris-Sud), Cécile Sicard-Roselli studies metallic nanoparticles and proteins under radiolysis conditions for anti-cancer therapeutic purposes. With her team, she recently succeeded in measuring and quantifying for the first time several reactive species formed after irradiation of gold nanoparticles.

Within the Physical Chemistry Laboratory (LCP - CNRS/Université Paris-Sud), Cécile Sicard-Roselli tries to unravel the mysteries of the mechanisms of action of metallic nanoparticles. Since 2006, the use of gold nanoparticles exposed to X-rays has shown their therapeutic potential by leading to the disappearance of tumours grafted on mice. Subsequently, many scientific studies have shown very different results, sometimes in contradiction with physical predictions. The research of Cécile Sicard-Roselli's team is part of this context: "We wanted to rationalize all these results. Our team has chosen to start from the physical phenomenon to understand how it works. We will then be able to use nanoparticles to their full potential."

To understand this phenomenon, the team quantified the chemical species responsible for the degradation of tumor cells. The radiolysis of water by electrons emitted by gold nanoparticles after irradiation (X-rays or gamma rays) is a well-established phenomenon. These electrons lead to the formation of highly reactive species (mainly OH radicals), which induce the destruction of different parts of the tumor cell and lead to tumor regression.

Until recently, very few research groups had attempted to measure the amount of electrons created by nanoparticles and the radicals that result from their action. The objective of the work of Cécile Sicard-Roselli's team was to capture reactive species (electrons and radicals) and to quantify them precisely. The team conducted numerous experiments to evaluate the production of electrons and OH radicals separately. The influence of nanoparticle concentration on the production of reactive species was also studied: "The result of these experiments is that the nanoparticle/water interface may be a privileged area for radical formation."

Through this work, Cécile Sicard-Roselli's team succeeded for the first time in measuring and quantifying several reactive species formed after irradiation of gold nanoparticles. Studies in collaboration with other teams of LCP lab are underway to model these new results. Other analyses are also being carried out on nanoparticles based on other elements, such as silver, bismuth or even diamonds. The results will provide a better understanding of how nanoparticles work in order to use them optimally in the treatment of tumours.

Manon Gilles, Emilie Brun, Cécile Sicard-Roselli. Quantification of hydroxyl radicals and solvated electrons produced by irradiated gold nanoparticles suggests a crucial role of interfacial water. Journal of Colloid and Interface Science. Volume 525, 1 September 2018, Pages 31-38.

 

Cécile Sicard-Rosseli ©Vincent Krieger

Cécile Sicard-Rosseli studied at the Faculty of Sciences in Orsay and then completed her doctorate in a CEA-Saclay laboratory on spectroscopy techniques applied to protein metal sites. After a three-year postdoctoral fellowship between industry and academia, she joined the Physical Chemistry Laboratory of Orsay as a lecturer to study the oxidative stress of proteins. Since 2005, she has been involved in activities on the use of metal nanoparticles for therapeutic applications.