2025/06/07 by P. Teles, Teles, Pedro
Chemistry · Earth and Planetary Sciences · #Free Radicals and Antioxidants #nanoparticles nucleation surface interactions
paper · pdf · doi:10.48550/arxiv.2506.06671
In this paper, we derive a variance-driven Local-Effect-Model (σ-LEM) to predict radiosensitization due to gold nanoparticles (AuNP). Assuming that the number of Au photo-ionisations scales strictly with particle volume VNP∝ R3, a linear relation between dose-enhancement ratio and concentration is achieved (DER = 1 + Kc,c), in which Kc is a beam-quality and nucleus-size-specific term, and c is the concentration in mM. Furthermore, assuming that the cascade energy deposition is log-normally distributed, the enhanced dose in each target voxel can be written as Denh = D0exp(σZ) with Z ∼ N(0,1) and width σ= √(2ln(1+Kc)). Assuming a linear-quadratic (LQ) dose response, a relation between cell survival and dose can be derived. Despite no closed form for the log-normal distribution, averaging over the entire domain using first- and second-order moments leads to three possible closed forms: variance-only, mixed-term, and second-order. These three variants adapt well to low-concentration, mid-concentration, and high-concentration regimes. The model was tested for Bovine aortic endothelial cells (BAEC) results taken from a Local Effect Model (LEM) and experimental values. The model agrees within ≤ 2.5% with the experimental and LEM data, but presents significant changes to the conceptual results obtained with the LEM, in particular indicating that AuNP dose enhancement is mostly α-driven, as posited previously by other authors. These findings are further developed in the manuscript. The theoretical framework presented here collapses radiobiological outcomes to three experimentally controllable variables -- beam quality, nucleus size, and intracellular concentration c -- while retaining mechanistic fidelity. Additional tests should be made to further confirm the validity of the model.