The original finding of the group is that combining platinum nanoparticles of 3 nm diameter and fast carbon ion irradiation (hadrontherapy) constitutes an efficient method to induce strong biological damage. It has been demonstrated in particular that the addition of nanoparticles to DNA amplifies by a factor of two the number of breaks in the helix and, more importantly, enhances the complexity and thus the lethality of the damage.
The sensitization effect has been ascribed to ionization processes in the metal, which are initiated by incoming ions and auto-amplified into the nanoparticles. The consequence of this fast excitation phenomenon is a neat amplification of the physical–chemical processes that lead to DNA damage, and particularly to the badly repaired double-strand breaks.
Metal nanoparticles present two main advantages: specific electronic properties when irradiated by highly ionizing radiation (such as fast ions), and possible surface coating for site-specific targeting. When combined with the ballistic properties of carbon ions, the use of metal nanoparticles opens up promising alternatives for future cancer therapy.
This work, led by Dr Lacombe, is based on the fruitful collaboration between French and Japanese teams. The project features sophisticated techniques and expertise including irradiation by a fast ion beam, which has been performed in the medical centre of Chiba (HIMAC, Chiba, Japan), a leader in hadrontherapy; the synthesis of nanoparticles by a unique method of radiolysis and handling with DNA, which has been optimized in Orsay, France.
This new branch of research, which associates radiation biology and nanoscience, is only at the beginning of its development and a more detailed understanding of the mechanisms involved is crucial to better optimize and control the combined technique.
Investigations at the molecular, but also at the cellular scale will be the subject of future work.