Unlocking atom-specific radiotherapy - DNA backbone breakage caused by X-ray photoactivation.

The effectiveness of radiation therapy can be enhanced by understanding the fragmentation mechanisms of iodine-doped DNA oligonucleotide under tender X-rays, as explored experimentally and computationally in our study. By primarily targeting iodine atoms above their L-edge ionization energies, we observed a significant increase in the production of fragments critical to DNA backbone breakage, particularly within mass ranges associated with phosphate and sugar groups. The mass spectroscopy experiments demonstrated that iodine-doped DNA oligonucleotides undergo intense fragmentation at long distances from the initial photoactivation site. Born-Oppenheimer based molecular dynamics simulations confirmed the generation of numerous small fragments, including reactive oxygen species, which are pivotal in enhancing the radiation damage. These findings highlight the effectiveness of iodine doping in amplifying DNA damage in radiotherapy iodine photoactivation, thereby improving the potential for targeted cancer treatment.