Effects of Titanium Dioxide Nanoparticles on the Hprt Gene Mutations in V79 Hamster Cells.

Alena Kazimirova,Ricard Marcos,Magdalena Barancokova,Laura Rubio,Maria Dusinska,Naouale El Yamani,Alba García-Rodríguez

doi:10.3390/nano10030465

Abstract

The genotoxicity of anatase/rutile TiO2 nanoparticles (TiO2 NPs, NM105 at 3, 15 and 75 µg/cm2) was assessed with the mammalian in-vitro Hypoxanthine guanine phosphoribosyl transferase (Hprt) gene mutation test in Chinese hamster lung (V79) fibroblasts after 24 h exposure. Two dispersion procedures giving different size distribution and dispersion stability were used to investigate whether the effects of TiO2 NPs depend on the state of agglomeration. TiO2 NPs were fully characterised in the previous European FP7 projects NanoTEST and NanoREG2. Uptake of TiO2 NPs was measured by transmission electron microscopy (TEM). TiO2 NPs were found in cytoplasmic vesicles, as well as close to the nucleus. The internalisation of TiO2 NPs did not depend on the state of agglomeration and dispersion used. The cytotoxicity of TiO2 NPs was measured by determining both the relative growth activity (RGA) and the plating efficiency (PE). There were no substantial effects of exposure time (24, 48 and 72 h), although a tendency to lower RGA at longer exposure was observed. No significant difference in PE values and no increases in the Hprt gene mutant frequency were found in exposed relative to unexposed cultures in spite of evidence of uptake of NPs by cells.

Highlights

Nano-sized or ultrafine titanium dioxide particles (TiO2 NPs) are among the most widely used nanomaterials
The aim of our work is to investigate whether TiO2 NPs induce mutagenic effect in the Hypoxanthine guanine phosphoribosyl transferase (Hprt) gene, and whether this effect depends on the dispersion procedure used, e.g. on different states of agglomeration
As NPs change their properties depending on the surrounding environment, we measured extrinsic properties of TiO2 NPs

Summary

Introduction

Nano-sized or ultrafine titanium dioxide particles (TiO2 NPs) are among the most widely used nanomaterials. In-vivo and in-vitro studies have reported conflicting results; some indicate that TiO2 NPs are genotoxic [6,7,8,9], whereas others give negative results [8,10,11,12]. This inconsistency is related to the different particle types used, with different NP sizes and physico-chemical properties, NP dispersion and exposure conditions, as well as to the use of different cell culture media, cellular models, and test methods [13,14,15,16]. TiO2 NPs can be treated as potentially hazardous compounds [5] consistent with the fact that TiO2 itself is classified as a class 2B carcinogen [17]

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