Synthesis of spherical and rods-like titanium oxide nanoparticles (TiO2 NPs) and evaluation of their cytotoxicity towards colon cells in vitro.

Titanium oxide nanoparticles (TiO₂ NPs) are currently used as ingredients in medicines and sunscreens. Unfortunately, recent information about TiO₂ NPs indicates their undesirable biological effect on colon cells. Therefore, the aim of this work was to synthesize and evaluate the physicochemical characterization of spherical (TiO₂ NSs) and rods-like (TiO₂ NRs) NPs, followed by assessment their cytotoxicity. For this purpose, both normal colon epithelial cells (CRL-1790) and cancerous colon cells (SW480) were used. Scanning transmission electron microscopy (STEM) showed that TiO₂ NSs with a diameter of ≈10 nm and TiO₂ NRs with the size of the longer axis ≈25 nm and shorter axis ≈3 nm were obtained. Based on the selected area electron diffraction (SAED) patterns, it was found that crystalline phases were obtained for both TiO₂ NPs. The UV-Vis spectra showed no contamination of TiO₂ NPs. Zeta potential values were 9.7 mV and 3.1 mV for NSs and NRs, respectively. Cytotoxicity of TiO₂ NPs was assessed using the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium) test for various concentration of NPs. The cytotoxic effect for both TiO₂ NPs was visible for concentration of 75 μg/ml (for CRL-1790) and 50 μg/ml (for SW480) and higher, and it did not depend on the shape. Moreover, both types of TiO₂ NPs (in higher concentration) induce the generation of reactive oxygen species (ROS) in cells cultured with these NPs. Holotomographic microscopy studies showed increased cellular uptake of TiO₂ NPs by SW480. The obtained results for the synthesized TiO₂ NPs are a promising prospect for their use in biomedical application.