ACHILE

Fundamental chemical processes in Condensed Phase

Permanent scientific members of the team : Mehran Mosafavi (PR); Sergey Denisov (CR); Jacqueline Belloni (DR); Dimitra Markovitsi (DR)

ELYSE Permanent support Accelerator / Laser pump source / Chemistry  : Jean-Philippe Larbre (IEHC, ELYSE Accelerator, Operations Manager); Audrey Gayral (AI, Optics and Laser); Mireille Benoît (IE, Operations Manager Laboratoire de Synthèse et de Caractérisation des Nanomatériaux)

Development : Dr. Daniel Adjei (IR: Chemical Analysis), Head of the CNRS bilateral collaboration France-Ghana

The Team studies primary physico-chemical processes induced by radiation (accelerated electrons, UV-visible light) in condensed phases. They are probed by transient absorption spectroscopy from the femtosecond to the millisecond time-scales. The majority of activities are closely related to the ELYSE set-up. In addition to classical optical pump-probe experiments, ELYSE offers a unique worldwide possibility to perform pulse radiolysis experiments with picosecond resolution.

The examined processes include excited state relaxation, solvation effects, electron transfer, reaction dynamics of radicals. In particular, the transformation of the spatially anisotropic energy distribution, generated by ionizing radiation, toward homogenous patterns is characterized. The studied systems range from pure solvents to various organic molecules, metal nanoparticles and DNA (mononucleotides, duplexes and guanine quadruplexes) in solution.

The team is strongly involved in the development and functioning of ELYSE, which hosts numerous researchers from other national and international institutions.

On-going-projects

Transient absorption of anionic radicals

The project aims to study the evolution of excited states of transient anion radicals in DNA/peptide models in aqueous solution, focusing on the quantum efficiency of state-to-state transitions. These studies of excited state chemistry are crucial because of their potential role in reductive damage to DNA/peptides through the creation of excited anion radicals that undergo irreversible dissociation. Using a new radiolysis spectroscopy method called "Pump(electron pulse)-Repump(laser)-Probe(supercontinuum)", replacing the traditional pump with an electron pulse, this innovative research has implications for cancer . This innovative research has significant implications for cancer radiotherapy techniques, modeling ionization radiation interaction, and understanding DNA and peptide damage. Furthermore, it addresses scientific and technological challenges by expanding the capabilities of pulse radiolysis techniques and aims to make the experimental data generated accessible to the entire research community.

Charge transfer processes induced by ionizing radiation

The primary processes of oxidation and reduction of molecular systems under ionizing radiation are studied on very varied time scales: from the sub-nanosecond to the second, by means of radiolysis by electron pulses coupled with time-resolved optical absorption spectroscopy.

Radiation Induced processes in DNA

The primary processes triggered upon direct absorption of UV radiation by DNA (single strands, duplexes, G-Quadruplexes) are studied by time-resolved optical spectroscopy. Most of the studies have been performed in the frame of the European Training Network LightDyNAmics (https://lightdynamics.eu/).

Related publications:

  • Gustavsson, T. and D. Markovitsi (2023) The Ubiquity of High-Energy Nanosecond Fluorescence in DNA Duplexes. J. Phys. Chem. Lett. 14, 2141-2147 (invited perspective).
  • Balanikas, E., T. Gustavsson and D. Markovitsi (2023) Fluorescence of Bimolecular Guanine Quadruplexes: From Femtoseconds to Nanoseconds. J Phys Chem B 127, 172–179.
  • Vaya, I., T. Gustavsson and D. Markovitsi (2022) High-Energy Long-Lived Emitting Mixed Excitons in Homopolymeric Adenine-Thymine DNA Duplexes. Molecules 27, 3558.
  • Balanikas, E., A. Banyasz, G. Baldacchino and D. Markovitsi (2022) Deprotonation Dynamics of Guanine Radical Cations. Photochem. Photobiol. 98, 523-531 (invited review).
  • Gustavsson, T. and D. Markovitsi (2021) Fundamentals of the Intrinsic DNA Fluorescence. Acc. Chem. Res. 54, 1226-1235.
  • Balanikas, E., L. Martinez-Fernandez, G. Baldacchino and D. Markovitsi (2021) Electron Holes in G-Quadruplexes: The Role of Adenine Ending Groups. Int. J. Mol. Sci. 22, 13436.
  • Balanikas, E., L. Martinez-Fernadez, R. Improta, P. Podbevsek, G. Baldacchino and D. Markovitsi (2021) The Structural Duality of Nucleobases in Guanine Quadruplexes Controls Their Low-Energy Photoionization. J. Phys. Chem. Lett. 12, 8309−8313.
  • Balanikas, E. and D. Markovitsi (2021) DNA photoionization: from high to low energies. In DNA Photodamage: From Light Absorption to Cellular Responses and Skin Cancer. (Edited by R. Improta and T. Douki), pp. 37-54. RSC, Cambridge.