Evaluating the Use of TiO Nanoparticles for Toxicity Testing in Pulmonary A549 Cells.

Purpose: Titanium dioxide nanoparticles, 25 nm in size of crystallites (TiO P25), are among the most produced nanomaterials worldwide. The broad use of TiO P25 in material science has implied a request to evaluate their biological effects, especially in the lungs. Hence, the pulmonary A549 cell line has been used to estimate the effects of TiO P25. However, the reports have provided dissimilar results on caused toxicity. Surprisingly, the physicochemical factors influencing TiO P25 action in biological models have not been evaluated in most reports. Thus, the objective of the present study is to characterize the preparation of TiO P25 for biological testing in A549 cells and to evaluate their biological effects.

Methods: We determined the size and crystallinity of TiO P25. We used four techniques for TiO P25 dispersion. We estimated the colloid stability of TiO P25 in distilled water, isotonic NaCl solution, and cell culture medium. We applied the optimal dispersion conditions for testing the biological effects of TiO P25 (0-100 µg.mL) in A549 cells using biochemical assays (dehydrogenase activity, glutathione levels) and microscopy.

Results: We found that the use of fetal bovine serum in culture medium is essential to maintain sufficient colloid stability of dispersed TiO P25. Under these conditions, TiO P25 were unable to induce a significant impairment of A549 cells according to the results of biochemical and microscopy evaluations. When the defined parameters for the use of TiO P25 in A549 cells were met, similar results on the biological effects of TiO P25 were obtained in two independent cell laboratories.

Conclusion: We optimized the experimental conditions of TiO P25 preparation for toxicity testing in A549 cells. The results presented here on TiO P25-induced cellular effects are reproducible. Therefore, our results can be helpful for other researchers using TiO P25 as a reference material.