Free-electron production from nucleotides upon collision with charged carbon ions

Abstract

Ion-beam cancer therapy has become increasingly favored worldwide in treatment of certain types of cancer over the last decade. Whereas the clinical effects of the therapy are well documented, the understanding of the underlying physical mechanisms is somewhat incomplete. The problem arises due to the multiscale nature of the effects involved in ion-beam cancer therapy, as the effects range from quantum-mechanical to macroscopic scales. The present study investigates the production of free electrons in the vicinity of the Bragg peak through quantum-mechanical simulations of the collision between a C 4+ ion with a cytosine-guanine nucleotide pair taken from a DNA double helix. Time-dependent density-functional theory was employed using the OCTOPUS 6.0 software. The results show that such a collision triggers the release of a large amount of electrons into the cellular environment, as only a fraction is captured by the C 4+ ion. Furthermore, it is demonstrated that the impact angle and projectile kinetic energy have much more influence on the number of ejected electrons than the impact parameter.

Multi-charged ion-water molecule collisions in a classical-trajectory time-dependent mean-field theory

“…The study of collisions with such ions is more scarce but it is being developed lately for both low-charge [30][31][32] and high-charge projectiles [33][34][35][36][37]. The collisions of ions with biomolecules are being investigated as well [38][39][40].…”

Introducing VIKING: A Novel Online Platform for Multiscale Modeling

“…Computational methods have in recent decades increasingly been used to model complex molecular systems and have in particular been extensively employed in the study of the biophysical and biochemical processes in living organisms. − The computational modeling tools allow researchers to study molecular processes and effects that are difficult or even impossible to probe experimentally, such as quantum mechanical effects, − diffusion of small molecules in various intracellular environments, , protein conformational changes, − and self-assembly of biomembranes …”

“…Processes occurring at different time and length scales can be modeled using different methods. (a) Ions penetrating a molecule in ion beam therapy and (b) absorption spectra of ligand molecules, which may be crucial for biological function, can be modeled through computational quantum chemistry. (c) Diffusion of small molecules in various biomolecular environments, , (d) ensembles of possible conformations of mobile parts of proteins, and (e) larger scale conformational changes and adhesion to surfaces of proteins can all be studied through MD simulations.…”

Non-perturbative scaling behavior for net ionization of biologically relevant molecules by multiply-charged heavy-ion impact

“…The RNA base uracil (C 4 H 4 N 2 O 2 ) was chosen as a candidate for extensive experimentation and was reported on together with theoretical analyses [2,3]. Theoretical treatment of ionization of these biomolecules escapes at this point the capabilities of sophisticated quantum-mechanical modelling, but first attempts have been made [4][5][6]. The net ionization cross sections for biomolecules are very large due to their size and number of available valence electrons.…”