Recently was shown that vermiculite with chlorohexidine exhibits the antibacterial activity, but impact of stand-alone vermiculite on organisms is still not completely understood.

Here we test the effect of vermiculite on male of Wistar rats. The animals were divided into three experimental groups of ten animals and one control group of five animals. In all experimental groups, we applied a vermiculite in a precisely defined quantity on the same area of buccal mucosa in the left vestibule in 24 h period for ten days. After this period, the first group was euthanized. Animals of the second and third groups were treated with vermiculite for next ten days in 48 h interval and at the end of this period the second group was euthanized. The third group was kept for next ten day without the application to see if long-term changes will appear. After this period the third group and control animals were euthanized. Samples for histological examination were collected. Tissues were fixed in 4% pfa and serial histological sections were stained in haematoxylin–eosin.

Buccal mucosa, tongue, esophagus and stomach showed a completely physiological structure, without any inflammatory reaction. Only mild changes in the gastrointestinal organs with increased presence of leukocyte were presented. Our analysis demonstrated that vermiculite is not toxic for rats.

Therefore, these results suggest that vermiculite may be used as matrix for future development of new types of nanocomposite biomaterials with antibacterial activity.

Work was supported by Nanotechnology Centre, VŠB-TU Ostrava and University hospital Ostrava, Czech Republic.

Conflict of interest: None declared.