Changes in arsenate bioaccumulation, subcellular distribution, depuration, and toxicity in Artemia salina nauplii in the presence of titanium dioxide nanoparticles

Abstract

Titanium dioxide nanoparticles (nano-TiO₂) can absorb ambient pollutants as well as modify their bioavailability in organisms. This study investigated the toxicity, accumulation, subcellular distribution, efflux and biochemical response of arsenate (As(V)) in the nauplii of Artemia salina after nano-TiO₂ introduction. Results showed higher As(V) EC₅₀ values in nauplii (by a magnitude of from 1.97 to 2.76) compared to the control (nano-TiO₂ free) as we increased nano-TiO₂ concentrations from 1 to 1000 mg L⁻¹. Arsenic (As) accumulation was also significantly facilitated by nano-TiO₂. As a result, we found that As(V) bioavailability differed between treatments (experiment and control). Moreover, As efflux rates were from 0.0584 ± 0.0083 to 0.3510 ± 0.0523 h⁻¹, rising as nano-TiO₂ concentrations increased. Along with As adsorption onto nano-TiO₂ in exposure media, enhanced efflux could be related to a possible increase in adsorption in the gut of nauplii. Furthermore, we found that the As percentage in biologically active metal (BAM) fractions significantly decreased after the addition of 10 mg L⁻¹ nano-TiO₂, while the fractional percentage of As increased in cellular debris. These lower As proportions in the sensitive fractions of cells could indicate As(V) toxicity inhibition, which is also supported by the callback of biochemical response in the presence of nano-TiO₂. Our results indicated that nano-TiO₂ could alleviate As(V) toxicity in A. salina nauplii by enhancing efflux and decreasing the proportion of As in the sensitive fractions of cells. Accordingly, more attention should be paid to the influence of nano-TiO₂ on As(V) assimilation in the digestive tract.