In vivo effect of industrial titanium dioxide nanoparticles experimentally exposed to hairless rat skin

Abstract

We morphologically investigated animal skin exposed to W/O emulsion containing 10 wt % ultrafine TiO₂ particles that had been characterized. After 4 h, exposed skin was investigated by light microscopy, confocal laser scanning microscopy (CLSM) and electron microscopy with energy-dispersive X-ray spectrometry (EDX). Light microscopic evaluation was also performed on the exposed skin after 24, 72 and 168 h. Light microscopy did not show any morphological and immunohistochemical changes in the skin. Electron microscopy revealed that the most TiO₂ particles were localized in the interfollicular stratum disjunctum and the keratinized layer of follicular infundibulum. No TiO₂ particles were detected in the viable skin, which was confirmed by EDX. Furthermore, we demonstrated a specific TiO₂ affinity to the follicular opening area by light microscopy and low-vacuum scanning electron microscopy with EDX. Our study suggests that TiO₂ particles neither penetrate into viable cell layers nor biologically cause any cellular changes.

Keywords::

• Titanium dioxide
• nanoparticle
• skin exposure
• hairless rat

Declaration of interest: This work was funded by New Energy and Industrial Technology Development Organization of Japan (NEDO) Grant “Evaluating risks associated with manufactured nanomaterials (P06041)”. The authors would like to report no conflict of interests. The authors are entirely responsible for the content and writing of the manuscript.