# The effects of iron oxide nanoparticles on antioxidant capacity and response to oxidative stress in Mozambique tilapia (Oreochromis mossambicus, Peters 1852)

## TL;DR

This study shows that iron oxide nanoparticles cause long-term oxidative stress and tissue damage in Mozambique tilapia, highlighting environmental risks.

## Contribution

The study reveals long-term nanotoxicity and tissue accumulation of IONPs in fish, even after exposure stops.

## Key findings

- IONPs increased hydrogen peroxide and lipid peroxidation in gill, liver, and brain tissues.
- Antioxidant enzyme activity was altered in exposed fish.
- Adverse effects persisted for 60 days after exposure ended.

## Abstract

Recent research has raised concern about the biocompatibility of iron oxide nanoparticles (IONPs), as they have been reported to induce oxidative stress and inflammatory responses, whilst prolonged exposure to high IONP concentrations may lead to cyto-/genotoxicity. Besides, there is concern about its environmental impact. The aim of our study was to investigate the effects of IONPs on the antioxidant defence system in freshwater fish Mozambique tilapia (Oreochromis mossambicus, Peters 1852). The fish were exposed to IONP concentration of 15 mg/L over 1, 3, 4, 15, 30, and 60 days and the findings compared to a control, unexposed group. In addition, we followed up the fish for 60 days after exposure had stopped to estimate the stability of oxidative stress induced by IONPs. Exposure affected the activity of antioxidant and marker enzymes and increased the levels of hydrogen peroxide and lipid peroxidation in the gill, liver, and brain tissues of the fish. Even after 60 days of depuration, adverse effects remained, indicating long-term nanotoxicity. Moreover, IONPs accumulated in the gill, liver, and brain tissues. Our findings underscore the potential health risks posed to non-target organisms in the environment, and it is imperative to establish appropriate guidelines for safe handling and disposal of IONPs to protect the aquatic environment.