Method for toxicity test of titanium dioxide nanoparticles in ciliate protozoanTetrahymena

Abstract

Titanium dioxide (TiO2) nanoparticles have a high surface-to-mass ratio and rapidly aggregate in water causing great difficulties for toxicity test exposed to aquatic organisms or other cell lines. This study uses a cell viability kit for routine toxicity test of TiO2 as well as other nanoparticles which accumulate in the aquatic environment. Tetrahymena immediately endocytoses TiO2 nanoparticles and stores them in food vacuoles until the particles undergo exocytosis as larger aggregates. However, during the process of endocytosis and exocytosis, TiO2 particles interfere with cell growth and consequently induce acute toxicity. It exerted high cell growth inhibition at 20 h incubation and induces significant cytotoxic effects. Surprisingly, the effect of TiO2 decreases at 40 h incubation, due to the recovery of cell growth and reduction of the cytotoxicity of the particles.

Nanoparticulat Printex 90 and Titanium Dioxide Stimulate Catecholamine Production in Ciliated Protozoan, Tetrahymena thermophila

“…However, the molecular mechanism of this particle internalization into Tetrahymena was not clear. In addition, the size distribution and zeta-potential of these two nanoparticles were not measured in PPY-medium in this study; size distribution of nanoparticles in PPY-medium was shown in our previous literature [23].…”

“…Nevertheless, nanoparticle tends to accumulate in the well plates due to the presence of complex PPY medium with the association of many ions. It is also recently reported upon a microscopic study that this accumulation of nanoparticle increases significantly when Tetrahymena species was cultivated in the PPY medium [23]. Tetrahymena cell internalize all free nanoparticles and finally exocytose them as larger aggregates into the culture medium, and this process continues until free small and visible nanoparticles are present the PPY-medium.…”

“…This unconquered effect of nanoparticles was explained in the literature [23]. The authors were reported that higher concentration of TiO 2 particle causes cytotoxicity to cells.…”

“…Nanoparticles suspensions were test to unicellular ciliate protozoan cell, Tetrahymena thermophila SB210 for catecholamine homeostasis. The growth maintenance of this cell was described in the literature [23]. Tetrahymena cell was acclimatized in fresh PPY-medium by twice successive reseedings for producing exponential cell.…”

“…The aquatic organism, Tetrahymena synthesizes dopamine, noradrenaline and adrenaline at significant level although this organism does not contain adrenal medulla or nervous system [22]. As well, literature has recently been revealed that TiO 2 nanoparticle causes cytotoxicity to the Tetrahymena [23]. However, our previous literature showed that the prenatal exposure of TiO 2 causes the increase of dopamine and its metaboloite in the different region of the brain in mice [24].…”