Role of Titanium Dioxide Nanoparticles in the Elevated Uptake and Retention of Cadmium and Zinc in Daphnia magna

Abstract

Titanium dioxide nanoparticles (nano-TiO(2)) are now widely applied in consumer products, and the dispersion of nano-TiO(2) may adsorb metals and modify their behavior and bioavailability in the aquatic environment. In the present study, the aqueous uptake, dietary assimilation efficiency (AE), and efflux rate constant (k(e)) of two toxic metals (cadmium-Cd, and zinc-Zn) adsorbed on nano-TiO(2) in a freshwater zooplankton Daphnia magna were quantified. The biokinetics was then compared to daphnids that were exposed only to dissolved metals as controls. The aqueous uptake of Cd and Zn involved an initial rapid uptake and then an apparent saturation, and the uptake of metals was accompanied by an ingestion of nano-TiO(2). The AEs of Cd and Zn adsorbed on nano-TiO(2) were 24.6 ± 2.4-44.5 ± 3.7% and 30.4 ± 3.4-51.8 ± 5.0%, respectively, and decreased with increasing concentrations of nano-TiO(2). Furthermore, the difference between the AEs of Cd and Zn indicated that the desorption of Cd and Zn from nano-TiO(2) may have occurred within the gut of daphnids. With the use of algae as carrier, the AEs of Cd and Zn adsorbed on nano-TiO(2) were significantly higher than those of Cd and Zn directly from nano-TiO(2). The efflux rate constants of Cd and Zn adsorbed on nano-TiO(2) in the zooplankton were significantly lower than those of Cd and Zn not adsorbed on nano-TiO(2). Our study shows that the uptake and retention of toxic metals is enhanced when they are adsorbed on nano-TiO(2), and suggests more attention be paid to the potential influences of nano-TiO(2) on the bioavailability and toxicity of other contaminants.

Effects of titanium dioxide nanoparticles on lead bioconcentration and toxicity on thyroid endocrine system and neuronal development in zebrafish larvae

“…In addition, previous studies have pointed out the enrichment of heavy metals in muscle, gills, liver, and kidney of fish (Fazio et al, 2014;Svecevicius et al, 2014;Wei et al, 2014). The NPs enhance the uptake heavy metal and organic toxicants (Baun et al, 2008;Tan et al, 2012;Wang et al, 2012Wang et al, , 2014. The previous studies also reported the enhanced uptake of toxicants in the presence of NPs, can greatly affect the toxicity of potential environmental pollutants (e.g., heavy metal and organic toxicants) Wang et al, 2014).…”

“…For instance, a previous study focused on the bioconcentration of the e-waste (BDE-209) that can be absorbed by nano-TiO 2 . Several previous studies focused on the enhanced bioaccumulation of metals mixed with NPs in aquatic ecosystems Tan et al, 2012). Their results showed that the increasing concentration of Cadmium and Zinc is related to NPs adsorption in Daphnia magna experiments.…”

Effect of titanium dioxide nanoparticles on the bioavailability, metabolism, and toxicity of pentachlorophenol in zebrafish larvae

“…Previous studies have reported that n-TiO 2 can adsorb heavy metals [4,34,44] or organic toxicants, including tributyltin, PBDEs, DDT and tetrachlorodibenzo-p-dioxin [TCDD] [12,13,45,46], while study showed the aggregation and subsequent sedimentation of nTiO 2 with tributyltin [12]. At the same time, we did not measure and (E) GSH content in larvae after exposure to PCP alone (0, 3, 10, and 30 g/L) and in the presence of n-TiO2 (0.1 mg/L) for 6 days.…”

“…Test n-TiO 2 solutions were prepared immediately prior to use by diluting the stock solutions with fresh charcoal-filtered water and sonicating (50 W/L, 40 kHz) for 20 min [34]. The test solution was renewed every 24 h with new n-TiO 2 to maintain relatively consistent levels of n-TiO 2 exposure.…”

Bioconcentration and metabolism of BDE-209 in the presence of titanium dioxide nanoparticles and impact on the thyroid endocrine system and neuronal development in zebrafish larvae

“…The sorption behavior of nano-TiO 2 includes physical sorption through electrostatic forces and chemical sorption through chemical bonding Yang et al, 2013). Several studies have reported that the uptake and retention of toxic metals in carp and Daphnia is enhanced when they are adsorbed on nano-TiO 2 (Tan et al, 2012;Zhang et al, 2007). Furthermore, toxicity at high concentrations of nano-TiO 2 (e.g.…”