Selenium Nanoparticles

This chapter is devoted to the toxicity and safety of selenium in nanoscale forms (selenium nanoparticles, SeNPs). It has been shown that in nature, Se exists mainly in the form of selenate (Se 6+ ), selenite (Se 4+ ), selenide (Se 2– ), and elemental Se (Se 0 ). The latter is insoluble in aqueous media, less toxic, and biologically inert. However, it has been found that in the form of nano-sized particles, elemental Se is not only biocompatible but also has a number of biological activities (antitumor, antimicrobial, protective). The biological properties of SeNPs, such as toxicity, selectivity for various types of cells, biocompatibility, and biodegradability, directly depend on their physical and chemical properties. The chapter reflects the main methods for the synthesis of SeNPs. Data showing that elemental Se in the form of nanoparticles (NPs) can modulate the activity of the antioxidant system and detoxification system are discussed. It has been demonstrated that Se in nanoscale form has a dose-dependent effect. High concentrations of SeNPs (more than 2 mg Se per kg) can cause the development of Se toxicity in mammals. Issues related to the interaction of SeNPs with living systems and the most probable toxicity mechanisms are also discussed.