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Risks of Inorganic Nanoparticles

Natural silver and gold nanoparticles exist at very low concentrations in the environment, which makes it difficult to directly evaluate their toxicity.Studies have also demonstrated both acute and chronic toxicity effects of nanoparticles using biological models such as Drosophila melanogaster.These engineered nanoparticles have been widely investigated and have shown various toxic effects on different living organisms, including bacteria, plants, and aquatic as well as terrestrial species.Furthermore, toxicity may vary depending on the type of organism exposed, as studies have shown differences in the response of Gram-positive and Gram-negative bacteria.The formation of ROS leads to oxidative stress, which can damage essential cellular components such as proteins, lipids, and DNA.This is mainly attributed to the presence of natural organic coatings that form in environmental conditions, which can reduce their reactivity and harmful effects.For example, in anoxic environments, nanoparticles can form insoluble metal sulfide layers on their surface, which slows down their dissolution rate.

Risks of Inorganic Nanoparticles

Natural silver and gold nanoparticles exist at very low concentrations in the environment, which makes it difficult to directly evaluate their toxicity. For this reason, most scientific studies have focused on engineered nanoparticles such as silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs). These engineered nanoparticles have been widely investigated and have shown various toxic effects on different living organisms, including bacteria, plants, and aquatic as well as terrestrial species. These toxic effects include genotoxicity, cytotoxicity, and ecotoxicity, indicating their potential impact on genetic material, cell structures, and the environment.

One of the primary mechanisms responsible for nanoparticle toxicity is the generation of reactive oxygen species (ROS). The formation of ROS leads to oxidative stress, which can damage essential cellular components such as proteins, lipids, and DNA. In addition to this, nanoparticles can release metal ions, such as Ag⁺, which further contribute to cellular damage either directly or indirectly. Studies have also demonstrated both acute and chronic toxicity effects of nanoparticles using biological models such as Drosophila melanogaster.

The level of toxicity is not constant and depends on several physicochemical properties of nanoparticles, including their surface chemistry, surface charge, and the type of coating used. Interestingly, natural nanoparticles are generally less toxic than engineered ones. This is mainly attributed to the presence of natural organic coatings that form in environmental conditions, which can reduce their reactivity and harmful effects. Furthermore, toxicity may vary depending on the type of organism exposed, as studies have shown differences in the response of Gram-positive and Gram-negative bacteria.

Environmental conditions also play a significant role in determining nanoparticle toxicity. For example, in anoxic environments, nanoparticles can form insoluble metal sulfide layers on their surface, which slows down their dissolution rate. As a result, the release of toxic metal ions is reduced, leading to lower overall toxicity. Therefore, factors such as environmental conditions, nanoparticle composition, and surface characteristics must all be considered when evaluating their toxic effects.