Toxicity Assessment of Nanomaterials

The nanomaterial (NM) repository encompasses a wide range of materials, including metal-based, metal oxide-based, carbon-based, silica-based, polymer-based, and composite-based nanomaterials. This field of science, nanotechnology, is witnessing an exponential expansion leveraging its application across several fields of science, including environmental and material sciences and in medical applications such as nanodrugs, nanocarriers, nanovaccines, bioimaging, and theranostic agents. Consequently, the burden of nanomaterials on the ecosystem, both terrestrial and marine, is rising rapidly, increasing the likelihood that living organisms will be exposed to NMs through various pathways, even in the absence of direct intake. Nanomaterial-induced toxicity, or nanotoxicity, manifests at the molecular, phenotypic, and genotypic levels. Besides oxidative stress, it involves depletion of antioxidants, upregulation of inflammatory cytokines, DNA damage, cell cycle disruption, RNA dysregulation, membrane and organelle damage, and autophagy activation. To assess nanotoxicity, assays for cell viability, enzyme levels, protein and cytokine expression, and tissue-specific toxicity markers are widely used. Traditional two-dimensional (2D) cultures are increasingly being replaced by three-dimensional (3D) models, organoids, and organ-on-chip systems that better mimic in vivo conditions. Therefore, long-term effect testing, a centralized toxicity database, and an established standard of protocols have become essential to guarantee the safety of NMs before commercialization.