A theoretical framework for predicting the oxidative stress potential of oxide nanoparticles

Abstract

In this paper we propose a theoretical model that predicts the oxidative stress potential of oxide nanoparticles by looking at the ability of these materials to perturb the intracellular redox state. The model uses reactivity descriptors to build the energy band structure of oxide nanoparticles, assuming a particle diameter larger than 20–30 nm and no surface states in the band gap, and predicts their ability to induce an oxidative stress by comparing the redox potentials of relevant intracellular reactions with the oxides' energy structure. Nanoparticles displaying band energy values comparable with redox potentials of antioxidants or radical formation reactions have the ability to cause an oxidative stress and a cytotoxic response in vitro. We discuss the model's predictions for six relevant oxide nanoparticles (TiO₂, CuO, ZnO, FeO, Fe₂O₃, Fe₃O₄) with literature in vitro studies and calculate the energy structure for 64 additional oxide nanomaterials. Such a framework would guide the development of more rational and efficient screening strategies avoiding random or exhaustive testing of new nanomaterials.

Keywords::

• Nanotoxicology
• particle toxicology
• computational chemistry

Declaration of interest: This work was supported by NanoTEST project under contract no. HEALTH-2008-201335 of the European Commission. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Notes

1. Experimentally, the excited electron has a measured reduction potential of about −4.5 eV vs. AVS and the hole has an oxidizing power of about −7.7 eV vs. AVS (Kava et al. 1996).

2. A work function of 5.20 ± 0.15 eV is measured for the Fe₃O₄(100) surface (Fonin et al. 2005).