In vitro toxicity evaluation of Ti4+-stabilized γ-Bi2O3 sillenites

- Bi12TiO20 microparticles with γ-Bi2O3 structure show low cytotoxicity.
- NO release/ROS production is directly/inversely proportional to γ-BTO concentration.
- NO release is more prominent for fibroblasts and neurons compared to hepatocytes.
- Intracellular ROS production is greater in the case of hepatocytes.
- Cell proliferation appears after longer treatment times (48 and 72 h).

We report results regarding the in vitro toxicology of γ-Bi2O3 represented by its isomorphous phase Bi12TiO20 (γ-BTO). The γ-BTO microparticles were synthesized by two methods: coprecipitation from a bismuth nitrate-tetrabutyl titanate solution and solid state reaction of Bi2O3 and TiO2 oxides. The structural and morphological characteristics of the obtained materials were determined using X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission (TEM) and scanning (SEM) electron microscopy. The elemental composition was investigated using energy dispersive spectrometry (EDS). The cytotoxicity and oxidative/nitrosative stress (intracellular reactive oxygen species (ROS) and nitric oxide (NO) release) induced by the studied microparticles in HepG2, SH-SY5Y and 3T3-L1 cell cultures were determined using the MTT, DCF-DA (2′,7′-dichlorfluorescein-diacetate) and Griess methods respectively. Depending on the cell type and γ-BTO concentration, results showed only weak cytotoxic effects after 24 h of γ-BTO exposure and cell proliferation effects for longer treatment times. Only reduced NO release increases (corresponding to high γ-BTO concentrations) were detected in case of SH-SY5Y and 3T3-L1 cells. The intracellular ROS production (higher for HepG2 cells) appeared inversely proportional to the γ-BTO concentration.The obtained results indicated a promising in vitro biocompatibility of γ-BTO and encourage further studies regarding its potential for biomedical applications.