Effects of BPQ binding on the nonadiabatic dynamics of excited electrons in poly(dG)-poly(dC) DNA under proton irradiation.

The interaction between DNA and small molecules is important for understanding the mechanisms of DNA-based multifunctional devices and has been extensively studied. However, there are few reports on such interactions in irradiation environments. Here, we investigate the nonadiabatic dynamic behaviors of excited electrons in double-stranded DNA bound to BPQ molecule upon proton irradiation, focusing on the energy deposition and electronic excitation dynamics as protons traverse the DNA along different channels. Our results reveal that the presence of BPQ significantly influences charge migration and DNA damage, with notable differences between CGvdW and CGcovalent adducts. The energy deposition process is highly dependent on charge density, and guanine exhibits higher excitation propensity than cytosine due to its structural characteristics. The BPQ molecule enhances DNA charge migration and promotes damage through secondary electron migration. These findings provide insights into the nonadiabatic dynamics of DNA under ionizing radiation and have implications for designing targeted electrophilic organics to improve radiotherapy efficacy.