Mechanistic Insights into Selenium Nanoparticles: Comparative Effects in Plant and Animal Systems.

Selenium nanoparticles (SeNPs), characterized by high bioavailability and low toxicity, have emerged as a class of redox-active nanomaterials that can modulate cellular oxidative states. However, previous reviews have largely considered the agricultural and animal-health applications of SeNPs separately, whereas an integrated comparison of their uptake, biotransformation, and redox-regulatory mechanisms across plants and animals has remained lacking. SeNPs uptake and transformation are influenced by species characteristics, nanoparticle properties, and application strategies. In plants, SeNPs lead to the modulation of reactive oxygen species (ROS) signaling, antioxidant defense systems, hormone-mediated responses, and stress-adaptation pathways. In animals, SeNPs contribute to selenium homeostasis through cellular uptake, bio-transformation, and regulation of selenoprotein biosynthesis, thereby affecting redox balance, immune responses, metabolism, and stress resistance. Here, we provide a mechanistic and comparative analysis of SeNPs mediated biological regulation in plants and animals, focusing on conserved and distinct pathways underlying their actions. Rather than acting as simple antioxidant supplements, SeNPs are increasingly recognized as modulators of intracellular redox homeostasis and ROS-dependent signaling networks. Plants primarily employ SeNPs to reprogram stress adaptation and metabolic plasticity, whereas animals integrate SeNPs-derived selenium into selenoprotein driven enzymatic antioxidant systems that maintain systemic redox homeostasis. Emerging evidence supports the view the conceptualization of SeNPs from passive antioxidant agents to dynamic regulators of redox signaling networks. Understanding these shared and distinct mechanisms will facilitate the rational development of SeNPs-based strategies for selenium biofortification, sustainable agriculture, and animal health.