nano-TiO₂ reduces bioavailability and biotransformation responses to crude oil WAF-associated PAHs in the European sea bass Dicentrachus labrax

The present study investigates the potential interaction between nano‑titanium dioxide (nano-TiO₂) and the water accommodated fraction (WAF) of crude oil and associated chemicals on bioavailability and biotransformation responses in the European sea bass (Dicentrarchus labrax). An in vivo (48-h) waterborne exposure with nano-TiO₂ (10 mgL^-1), crude oil WAF (0.068 gL^-1), alone and in combination was performed. Combined exposure significantly reduced levels of polycyclic aromatic hydrocarbons (PAH) in either seawater and fish fillets compared to WAF alone. A significant reduction in the expression of several biotransformation genes (cyp1a, gsta, erβ2, elmod2, abcb1 and abcc1) when nano-TiO₂ was combined with WAF was observed in fish liver, compared to WAF alone. EROD and GST enzyme activities were also significantly reduced. Nano-TiO₂ can reduce PAHs bioavailability in seawater and biological responses in European sea bass, suggesting a potential safe application of nano-TiO₂ for the remediation of crude oil WAF in the marine environment.