Toxicological Insights and Antimicrobial Mechanisms of Bismuth Trioxide Nanoparticles: Implications for Sustainable Bioapplications

The application of engineered nanomaterials in agriculture and environmental systems has raised concerns regarding biosafety and ecological impacts. Bismuth Trioxide nanoparticles (Bi₂O₃ NPs), known for their high chemical stability, semiconducting behavior, and strong antimicrobial efficacy, are increasingly proposed as environmentally safer alternatives to traditional pesticides. This review consolidates current evidence on the toxicological effects of Bi₂O₃ NPs across microbial and plant systems. Specifically, we analyze their mechanisms of antimicrobial action, including reactive oxygen species (ROS) generation and membrane disruption, alongside cytotoxic and phytotoxic responses in mammalian cells and plant models. Data indicate that Bi₂O₃ NPs exert selective antibacterial activity at concentrations as low as 0.75 μg/mL against P. aeruginosa, while cytotoxicity to human cells generally occurs above 50 μg/mL. Phytotoxic responses, such as root growth inhibition, vary with size, surface coating, and concentration. Despite promising antibacterial properties, knowledge gaps remain regarding long-term soil accumulation, non-target species effects, and molecular-level toxicity pathways. This review proposes a framework for standardized toxicity testing and encourages future studies incorporating omics tools, multiple trophic levels, and environmentally realistic exposure models to ensure safe, scalable deployment of Bi₂O₃ nanomaterials in applied biosciences.