## 3 Results
#### Genotoxicity Evaluation  
The evaluation of genotoxicity was performed by the in vitro micronucleleus test, recommended by the OECD [14]. The purpose of this test is to detect micronuclelei in the cytoplasm of interphase cells and to score their incidence. This test detects the clastogenic and anequgenic activity of some chemical agents. The micronucleleus assay has several advantages over the metaphase analysis, which is performed in the OECD Guidelines 473 and 475, to measure chromosome aberrations. Because micronuclelei in interphase cells can be assessed much more objectively than chromosomal aberrations in metaphase cells MN vit the preparations can be scored much more quickly [14]. This makes it practical to score thousands of cells per treatment. Finally, as micronuclelei may contain whole (lagging) chromosomes, there is the potential to detect aneuploidy-inducing agents that are currently very difficult to study in conventional chromosomal aberration tests. MNvit is the most widely used and reliable test for assessing genotoxic potential of a chemical agent [24]. As the lymphocyte cultures were developed without CytoB it was necessary to measure the RICC (Relative Increase in Cell Count) index to demonstrate the fact the cells in the culture had undergone cell division and to avoid false negative responses. According to RICC index, cytotoxicity was calculated for each concentration (Table 1). Comparative to negative control sample (Figure 6), the MN incidence analysis for the PDMS concentration of 2 mg/L and 4 mg/L indicated a relative high degree of genotoxicity with atypical and deformed nuclei, numerous acentric fragments, some of them linked by chromatin bridges (Figure 7a,b). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Compound Type**} & \multicolumn{3}{c}{**Compounds Concentration in Culture Medium**} \\ \cline{2-4}  & **2 mg/L** & **4 mg/L** & **8 mg/L** \\ \hline PDMS & 50.4 (\(\pm\)1.13) & 58.9 (\(\pm\)1.56) & 77.3 (\(\pm\)0.28) \\ PDMS-BF & 49 (\(\pm\)1.13) & 57.2 (\(\pm\)0.99) & 58 (\(\pm\)1.27) \\ PDMS-BF-TiO\({}_{2}\) & 49.1 (\(\pm\)0.57) & 51.4 (\(\pm\)0.42) & 58.1 (\(\pm\)0.71) \\ \hline PDMS—polydimethylsiloxane; BF—benzophenone; PDMS-BF-TiO\({}_{2}\)—PDMS-benzophenone-titanium dioxide nanoparticles; SD—standard deviation. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Cytotoxicity (%) of PDMS, PDMS-B and PDMS-B-TiO\({}_{2}\) in lymphocyte cell culture according to RICC index (\(\pm\)SD). Figure 6: Negative control sample. Interphase nuclei with normal morphology and dividing metaphase chromosomes (arrow) are observed. For the concentration of 8 mg/L PDMS the micronucleeli incidence could not be scored as the genetic material was damaged, the cytotoxicity exceeded the maximum allowed value (Table 2), turbidity, and precipitation visible by naked eye were found. If the cytotoxicity exceeds 60% it results in the appearance of micronucleeli as an adverse effect of cytotoxicity, so the incidence of MN as a result of genotoxic capacity cannot be assessed. This concentration of 8 mg/L of PDMS was too high to allow for micronucleeli scoring. Both genotoxic capacity and cytotoxicity of PDMS determined by higher concentration and by the fact that this compound could directly interact with DNA [25], which synergistically resulted in changing the quality and integrity of genetic material. PDMS-BF compound at 2 mg/L and 4 mg/L showed a relative high degree of genotoxicity (Figure 8a,b) but at 8 mg/L the MN incidence analysis indicated a high degree of genotoxicity and the presence of gross lesions in the genetic material. Atypical and deformed nuclei were common in this sample (Figure 8c,d). A statistically significant increase in micronucleeli incidence was observed from all the tested concentrations of PDMS and PDMS-BF, compared to the negative control (Table 2). Surprising results were obtained for PDMS-BF-TiO nanocomposite.